WIP: Metal shader backend para macOS

- Shaders MSL portados desde GLSL (vertex + fragment)
- Estructura básica de MetalShader class
- Device, command queue, pipeline y buffers creados
- CMakeLists.txt actualizado con Metal frameworks
- assets.txt incluye shaders .metal como opcionales

PENDIENTE:
- Implementar render() loop completo
- Obtener MTLTexture desde SDL_Texture
- Crear sampler state
- Testing en macOS real

Ver METAL_BACKEND_NOTES.md para detalles de implementación.

CMakeLists.txt

@@ -111,22 +111,35 @@ set(APP_SOURCES
 # Fuentes de librerías de terceros
 set(EXTERNAL_SOURCES
     source/external/jail_audio.cpp
-    source/external/jail_shader.cpp
     source/external/json.hpp
-    source/external/gif.cpp 
+    source/external/gif.cpp
 )
 
+# Fuentes del sistema de renderizado
+set(RENDERING_SOURCES
+    source/rendering/opengl/opengl_shader.cpp
+)
+
+# Añadir backend de Metal en macOS
+if(APPLE)
+    list(APPEND RENDERING_SOURCES
+        source/rendering/metal/metal_shader.mm
+    )
+    message(STATUS "Metal backend habilitado para macOS")
+endif()
+
 # Configuración de SDL3
 find_package(SDL3 REQUIRED CONFIG REQUIRED COMPONENTS SDL3)
 message(STATUS "SDL3 encontrado: ${SDL3_INCLUDE_DIRS}")
 
 # --- 2. AÑADIR EJECUTABLE ---
-add_executable(${PROJECT_NAME} ${APP_SOURCES} ${EXTERNAL_SOURCES})
+add_executable(${PROJECT_NAME} ${APP_SOURCES} ${EXTERNAL_SOURCES} ${RENDERING_SOURCES})
 
 # --- 3. DIRECTORIOS DE INCLUSIÓN ---
 target_include_directories(${PROJECT_NAME} PUBLIC
     "${CMAKE_SOURCE_DIR}/source"
     "${CMAKE_SOURCE_DIR}/source/external"
+    "${CMAKE_SOURCE_DIR}/source/rendering"
     "${CMAKE_BINARY_DIR}"
 )
 
@@ -154,6 +167,11 @@ elseif(APPLE)
     target_compile_definitions(${PROJECT_NAME} PRIVATE MACOS_BUILD)
     target_compile_options(${PROJECT_NAME} PRIVATE -Wno-deprecated)
     set(CMAKE_OSX_ARCHITECTURES "arm64")
+    # Enlazar frameworks de Metal
+    target_link_libraries(${PROJECT_NAME} PRIVATE
+        "-framework Metal"
+        "-framework QuartzCore"
+    )
 elseif(UNIX AND NOT APPLE)
     target_compile_definitions(${PROJECT_NAME} PRIVATE LINUX_BUILD)
 endif()

config/assets.txt

@@ -74,8 +74,13 @@ SOUND|${PREFIX}/data/sound/voice_recover.wav
 SOUND|${PREFIX}/data/sound/voice_thankyou.wav
 SOUND|${PREFIX}/data/sound/walk.wav
 
-# Shaders
+# Shaders OpenGL (Windows/Linux)
-DATA|${PREFIX}/data/shaders/crtpi.glsl
+DATA|${PREFIX}/data/shaders/crtpi_vertex.glsl
+DATA|${PREFIX}/data/shaders/crtpi_fragment.glsl
+
+# Shaders Metal (macOS) - opcionales
+DATA|${PREFIX}/data/shaders/crtpi_vertex.metal|optional
+DATA|${PREFIX}/data/shaders/crtpi_fragment.metal|optional
 
 # Texturas - Balloons
 ANIMATION|${PREFIX}/data/gfx/balloon/balloon0.ani

data/shaders/crtpi.glsl

@@ -1,237 +0,0 @@
-/*
-    crt-pi - A Raspberry Pi friendly CRT shader.
-
-    Copyright (C) 2015-2016 davej
-
-    This program is free software; you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by the Free
-    Software Foundation; either version 2 of the License, or (at your option)
-    any later version.
-
-
-Notes:
-
-This shader is designed to work well on Raspberry Pi GPUs (i.e. 1080P @ 60Hz on a game with a 4:3 aspect ratio). It pushes the Pi's GPU hard and enabling some features will slow it down so that it is no longer able to match 1080P @ 60Hz. You will need to overclock your Pi to the fastest setting in raspi-config to get the best results from this shader: 'Pi2' for Pi2 and 'Turbo' for original Pi and Pi Zero. Note: Pi2s are slower at running the shader than other Pis, this seems to be down to Pi2s lower maximum memory speed. Pi2s don't quite manage 1080P @ 60Hz - they drop about 1 in 1000 frames. You probably won't notice this, but if you do, try enabling FAKE_GAMMA.
-
-SCANLINES enables scanlines. You'll almost certainly want to use it with MULTISAMPLE to reduce moire effects. SCANLINE_WEIGHT defines how wide scanlines are (it is an inverse value so a higher number = thinner lines). SCANLINE_GAP_BRIGHTNESS defines how dark the gaps between the scan lines are. Darker gaps between scan lines make moire effects more likely.
-
-GAMMA enables gamma correction using the values in INPUT_GAMMA and OUTPUT_GAMMA. FAKE_GAMMA causes it to ignore the values in INPUT_GAMMA and OUTPUT_GAMMA and approximate gamma correction in a way which is faster than true gamma whilst still looking better than having none. You must have GAMMA defined to enable FAKE_GAMMA.
-
-CURVATURE distorts the screen by CURVATURE_X and CURVATURE_Y. Curvature slows things down a lot.
-
-By default the shader uses linear blending horizontally. If you find this too blury, enable SHARPER.
-
-BLOOM_FACTOR controls the increase in width for bright scanlines.
-
-MASK_TYPE defines what, if any, shadow mask to use. MASK_BRIGHTNESS defines how much the mask type darkens the screen.
-
-*/
-
-#pragma parameter CURVATURE_X "Screen curvature - horizontal" 0.10 0.0 1.0 0.01
-#pragma parameter CURVATURE_Y "Screen curvature - vertical" 0.15 0.0 1.0 0.01
-#pragma parameter MASK_BRIGHTNESS "Mask brightness" 0.70 0.0 1.0 0.01
-#pragma parameter SCANLINE_WEIGHT "Scanline weight" 6.0 0.0 15.0 0.1
-#pragma parameter SCANLINE_GAP_BRIGHTNESS "Scanline gap brightness" 0.12 0.0 1.0 0.01
-#pragma parameter BLOOM_FACTOR "Bloom factor" 1.5 0.0 5.0 0.01
-#pragma parameter INPUT_GAMMA "Input gamma" 2.4 0.0 5.0 0.01
-#pragma parameter OUTPUT_GAMMA "Output gamma" 2.2 0.0 5.0 0.01
-
-// Haven't put these as parameters as it would slow the code down.
-#define SCANLINES
-#define MULTISAMPLE
-#define GAMMA
-//#define FAKE_GAMMA
-//#define CURVATURE
-//#define SHARPER
-// MASK_TYPE: 0 = none, 1 = green/magenta, 2 = trinitron(ish)
-#define MASK_TYPE 2
-
-
-#ifdef GL_ES
-#define COMPAT_PRECISION mediump
-precision mediump float;
-#else
-#define COMPAT_PRECISION
-#endif
-
-#ifdef PARAMETER_UNIFORM
-uniform COMPAT_PRECISION float CURVATURE_X;
-uniform COMPAT_PRECISION float CURVATURE_Y;
-uniform COMPAT_PRECISION float MASK_BRIGHTNESS;
-uniform COMPAT_PRECISION float SCANLINE_WEIGHT;
-uniform COMPAT_PRECISION float SCANLINE_GAP_BRIGHTNESS;
-uniform COMPAT_PRECISION float BLOOM_FACTOR;
-uniform COMPAT_PRECISION float INPUT_GAMMA;
-uniform COMPAT_PRECISION float OUTPUT_GAMMA;
-#else
-#define CURVATURE_X 0.05
-#define CURVATURE_Y 0.1
-#define MASK_BRIGHTNESS 0.80
-#define SCANLINE_WEIGHT 6.0
-#define SCANLINE_GAP_BRIGHTNESS 0.12
-#define BLOOM_FACTOR 3.5
-#define INPUT_GAMMA 2.4
-#define OUTPUT_GAMMA 2.2
-#endif
-
-/* COMPATIBILITY
-   - GLSL compilers
-*/
-
-// Uniform para el tamaño de textura (pasado desde C++)
-uniform vec2 TextureSize;
-
-#if defined(CURVATURE)
-varying vec2 screenScale;
-#endif
-varying vec2 TEX0;
-varying float filterWidth;
-
-#if defined(VERTEX)
-//uniform mat4 MVPMatrix;
-//attribute vec4 VertexCoord;
-//attribute vec2 TexCoord;
-//uniform vec2 InputSize;
-//uniform vec2 OutputSize;
-
-void main()
-{
-#if defined(CURVATURE)
-	screenScale = vec2(1.0, 1.0); //TextureSize / InputSize;
-#endif
-	// Calcula filterWidth dinámicamente basándose en la altura de la textura
-	filterWidth = (768.0 / TextureSize.y) / 3.0;
-	TEX0 = vec2(gl_MultiTexCoord0.x, 1.0-gl_MultiTexCoord0.y)*1.0001;
-	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
-}
-#elif defined(FRAGMENT)
-
-uniform sampler2D Texture;
-
-#if defined(CURVATURE)
-vec2 Distort(vec2 coord)
-{
-	vec2 CURVATURE_DISTORTION = vec2(CURVATURE_X, CURVATURE_Y);
-	// Barrel distortion shrinks the display area a bit, this will allow us to counteract that.
-	vec2 barrelScale = 1.0 - (0.23 * CURVATURE_DISTORTION);
-	coord *= screenScale;
-	coord -= vec2(0.5);
-	float rsq = coord.x * coord.x + coord.y * coord.y;
-	coord += coord * (CURVATURE_DISTORTION * rsq);
-	coord *= barrelScale;
-	if (abs(coord.x) >= 0.5 || abs(coord.y) >= 0.5)
-		coord = vec2(-1.0);		// If out of bounds, return an invalid value.
-	else
-	{
-		coord += vec2(0.5);
-		coord /= screenScale;
-	}
-
-	return coord;
-}
-#endif
-
-float CalcScanLineWeight(float dist)
-{
-	return max(1.0-dist*dist*SCANLINE_WEIGHT, SCANLINE_GAP_BRIGHTNESS);
-}
-
-float CalcScanLine(float dy)
-{
-	float scanLineWeight = CalcScanLineWeight(dy);
-#if defined(MULTISAMPLE)
-	scanLineWeight += CalcScanLineWeight(dy-filterWidth);
-	scanLineWeight += CalcScanLineWeight(dy+filterWidth);
-	scanLineWeight *= 0.3333333;
-#endif
-	return scanLineWeight;
-}
-
-void main()
-{
-	// TextureSize ahora viene como uniform, no está hardcodeado
-#if defined(CURVATURE)
-	vec2 texcoord = Distort(TEX0);
-	if (texcoord.x < 0.0)
-		gl_FragColor = vec4(0.0);
-	else
-#else
-	vec2 texcoord = TEX0;
-#endif
-	{
-		vec2 texcoordInPixels = texcoord * TextureSize;
-#if defined(SHARPER)
-		vec2 tempCoord = floor(texcoordInPixels) + 0.5;
-		vec2 coord = tempCoord / TextureSize;
-		vec2 deltas = texcoordInPixels - tempCoord;
-		float scanLineWeight = CalcScanLine(deltas.y);
-		vec2 signs = sign(deltas);
-		deltas.x *= 2.0;
-		deltas = deltas * deltas;
-		deltas.y = deltas.y * deltas.y;
-		deltas.x *= 0.5;
-		deltas.y *= 8.0;
-		deltas /= TextureSize;
-		deltas *= signs;
-		vec2 tc = coord + deltas;
-#else
-		float tempY = floor(texcoordInPixels.y) + 0.5;
-		float yCoord = tempY / TextureSize.y;
-		float dy = texcoordInPixels.y - tempY;
-		float scanLineWeight = CalcScanLine(dy);
-		float signY = sign(dy);
-		dy = dy * dy;
-		dy = dy * dy;
-		dy *= 8.0;
-		dy /= TextureSize.y;
-		dy *= signY;
-		vec2 tc = vec2(texcoord.x, yCoord + dy);
-#endif
-
-		vec3 colour = texture2D(Texture, tc).rgb;
-
-#if defined(SCANLINES)
-#if defined(GAMMA)
-#if defined(FAKE_GAMMA)
-		colour = colour * colour;
-#else
-		colour = pow(colour, vec3(INPUT_GAMMA));
-#endif
-#endif
-		scanLineWeight *= BLOOM_FACTOR;
-		colour *= scanLineWeight;
-
-#if defined(GAMMA)
-#if defined(FAKE_GAMMA)
-		colour = sqrt(colour);
-#else
-		colour = pow(colour, vec3(1.0/OUTPUT_GAMMA));
-#endif
-#endif
-#endif
-#if MASK_TYPE == 0
-		gl_FragColor = vec4(colour, 1.0);
-#else
-#if MASK_TYPE == 1
-		float whichMask = fract((gl_FragCoord.x*1.0001) * 0.5);
-		vec3 mask;
-		if (whichMask < 0.5)
-			mask = vec3(MASK_BRIGHTNESS, 1.0, MASK_BRIGHTNESS);
-		else
-			mask = vec3(1.0, MASK_BRIGHTNESS, 1.0);
-#elif MASK_TYPE == 2
-		float whichMask = fract((gl_FragCoord.x*1.0001) * 0.3333333);
-		vec3 mask = vec3(MASK_BRIGHTNESS, MASK_BRIGHTNESS, MASK_BRIGHTNESS);
-		if (whichMask < 0.3333333)
-			mask.x = 1.0;
-		else if (whichMask < 0.6666666)
-			mask.y = 1.0;
-		else
-			mask.z = 1.0;
-#endif
-
-		gl_FragColor = vec4(colour * mask, 1.0);
-#endif
-	}
-}
-#endif

data/shaders/crtpi_fragment.glsl

@@ -0,0 +1,157 @@
+#version 330 core
+
+// Configuración
+#define SCANLINES
+#define MULTISAMPLE
+#define GAMMA
+//#define FAKE_GAMMA
+//#define CURVATURE
+//#define SHARPER
+#define MASK_TYPE 2
+
+#define CURVATURE_X 0.05
+#define CURVATURE_Y 0.1
+#define MASK_BRIGHTNESS 0.80
+#define SCANLINE_WEIGHT 6.0
+#define SCANLINE_GAP_BRIGHTNESS 0.12
+#define BLOOM_FACTOR 3.5
+#define INPUT_GAMMA 2.4
+#define OUTPUT_GAMMA 2.2
+
+// Inputs desde vertex shader
+in vec2 vTexCoord;
+in float vFilterWidth;
+#if defined(CURVATURE)
+in vec2 vScreenScale;
+#endif
+
+// Output
+out vec4 FragColor;
+
+// Uniforms
+uniform sampler2D Texture;
+uniform vec2 TextureSize;
+
+#if defined(CURVATURE)
+vec2 Distort(vec2 coord)
+{
+	vec2 CURVATURE_DISTORTION = vec2(CURVATURE_X, CURVATURE_Y);
+	vec2 barrelScale = 1.0 - (0.23 * CURVATURE_DISTORTION);
+	coord *= vScreenScale;
+	coord -= vec2(0.5);
+	float rsq = coord.x * coord.x + coord.y * coord.y;
+	coord += coord * (CURVATURE_DISTORTION * rsq);
+	coord *= barrelScale;
+	if (abs(coord.x) >= 0.5 || abs(coord.y) >= 0.5)
+		coord = vec2(-1.0);
+	else
+	{
+		coord += vec2(0.5);
+		coord /= vScreenScale;
+	}
+	return coord;
+}
+#endif
+
+float CalcScanLineWeight(float dist)
+{
+	return max(1.0 - dist * dist * SCANLINE_WEIGHT, SCANLINE_GAP_BRIGHTNESS);
+}
+
+float CalcScanLine(float dy)
+{
+	float scanLineWeight = CalcScanLineWeight(dy);
+#if defined(MULTISAMPLE)
+	scanLineWeight += CalcScanLineWeight(dy - vFilterWidth);
+	scanLineWeight += CalcScanLineWeight(dy + vFilterWidth);
+	scanLineWeight *= 0.3333333;
+#endif
+	return scanLineWeight;
+}
+
+void main()
+{
+#if defined(CURVATURE)
+	vec2 texcoord = Distort(vTexCoord);
+	if (texcoord.x < 0.0) {
+		FragColor = vec4(0.0);
+		return;
+	}
+#else
+	vec2 texcoord = vTexCoord;
+#endif
+
+	vec2 texcoordInPixels = texcoord * TextureSize;
+
+#if defined(SHARPER)
+	vec2 tempCoord = floor(texcoordInPixels) + 0.5;
+	vec2 coord = tempCoord / TextureSize;
+	vec2 deltas = texcoordInPixels - tempCoord;
+	float scanLineWeight = CalcScanLine(deltas.y);
+	vec2 signs = sign(deltas);
+	deltas.x *= 2.0;
+	deltas = deltas * deltas;
+	deltas.y = deltas.y * deltas.y;
+	deltas.x *= 0.5;
+	deltas.y *= 8.0;
+	deltas /= TextureSize;
+	deltas *= signs;
+	vec2 tc = coord + deltas;
+#else
+	float tempY = floor(texcoordInPixels.y) + 0.5;
+	float yCoord = tempY / TextureSize.y;
+	float dy = texcoordInPixels.y - tempY;
+	float scanLineWeight = CalcScanLine(dy);
+	float signY = sign(dy);
+	dy = dy * dy;
+	dy = dy * dy;
+	dy *= 8.0;
+	dy /= TextureSize.y;
+	dy *= signY;
+	vec2 tc = vec2(texcoord.x, yCoord + dy);
+#endif
+
+	vec3 colour = texture(Texture, tc).rgb;
+
+#if defined(SCANLINES)
+#if defined(GAMMA)
+#if defined(FAKE_GAMMA)
+	colour = colour * colour;
+#else
+	colour = pow(colour, vec3(INPUT_GAMMA));
+#endif
+#endif
+	scanLineWeight *= BLOOM_FACTOR;
+	colour *= scanLineWeight;
+
+#if defined(GAMMA)
+#if defined(FAKE_GAMMA)
+	colour = sqrt(colour);
+#else
+	colour = pow(colour, vec3(1.0 / OUTPUT_GAMMA));
+#endif
+#endif
+#endif
+
+#if MASK_TYPE == 0
+	FragColor = vec4(colour, 1.0);
+#elif MASK_TYPE == 1
+	float whichMask = fract(gl_FragCoord.x * 0.5);
+	vec3 mask;
+	if (whichMask < 0.5)
+		mask = vec3(MASK_BRIGHTNESS, 1.0, MASK_BRIGHTNESS);
+	else
+		mask = vec3(1.0, MASK_BRIGHTNESS, 1.0);
+	FragColor = vec4(colour * mask, 1.0);
+#elif MASK_TYPE == 2
+	float whichMask = fract(gl_FragCoord.x * 0.3333333);
+	vec3 mask = vec3(MASK_BRIGHTNESS, MASK_BRIGHTNESS, MASK_BRIGHTNESS);
+	if (whichMask < 0.3333333)
+		mask.x = 1.0;
+	else if (whichMask < 0.6666666)
+		mask.y = 1.0;
+	else
+		mask.z = 1.0;
+	FragColor = vec4(colour * mask, 1.0);
+#endif
+}

data/shaders/crtpi_fragment.metal

@@ -0,0 +1,152 @@
+//
+// CRT-Pi Fragment Shader - Metal Shading Language
+// Portado desde GLSL a MSL para macOS
+//
+
+#include <metal_stdlib>
+using namespace metal;
+
+// Configuración (equivalente a los #define en GLSL)
+constant bool SCANLINES = true;
+constant bool MULTISAMPLE = true;
+constant bool GAMMA = true;
+constant bool FAKE_GAMMA = false;
+constant bool CURVATURE = false;
+constant bool SHARPER = false;
+constant int MASK_TYPE = 2;  // 0=none, 1=green/magenta, 2=trinitron
+
+constant float CURVATURE_X = 0.05;
+constant float CURVATURE_Y = 0.1;
+constant float MASK_BRIGHTNESS = 0.80;
+constant float SCANLINE_WEIGHT = 6.0;
+constant float SCANLINE_GAP_BRIGHTNESS = 0.12;
+constant float BLOOM_FACTOR = 3.5;
+constant float INPUT_GAMMA = 2.4;
+constant float OUTPUT_GAMMA = 2.2;
+
+// Estructura de entrada (salida del vertex shader)
+struct VertexOut {
+    float4 position [[position]];
+    float2 texCoord;
+    float filterWidth;
+    // float2 screenScale;  // Solo si CURVATURE está activo
+};
+
+// Uniforms
+struct Uniforms {
+    float2 textureSize;
+};
+
+// Función para calcular el peso de la scanline
+float CalcScanLineWeight(float dist) {
+    return max(1.0 - dist * dist * SCANLINE_WEIGHT, SCANLINE_GAP_BRIGHTNESS);
+}
+
+// Función para calcular scanline con multisampling
+float CalcScanLine(float dy, float filterWidth) {
+    float scanLineWeight = CalcScanLineWeight(dy);
+    if (MULTISAMPLE) {
+        scanLineWeight += CalcScanLineWeight(dy - filterWidth);
+        scanLineWeight += CalcScanLineWeight(dy + filterWidth);
+        scanLineWeight *= 0.3333333;
+    }
+    return scanLineWeight;
+}
+
+// Entry point del fragment shader
+fragment float4 fragment_main(VertexOut in [[stage_in]],
+                              texture2d<float> colorTexture [[texture(0)]],
+                              constant Uniforms& uniforms [[buffer(1)]],
+                              sampler textureSampler [[sampler(0)]]) {
+
+    float2 texcoord = in.texCoord;
+
+    // Si CURVATURE estuviera activo, aquí iría la función Distort()
+
+    float2 texcoordInPixels = texcoord * uniforms.textureSize;
+
+    float2 tc;
+    float scanLineWeight;
+
+    if (!SHARPER) {
+        // Modo normal (no SHARPER)
+        float tempY = floor(texcoordInPixels.y) + 0.5;
+        float yCoord = tempY / uniforms.textureSize.y;
+        float dy = texcoordInPixels.y - tempY;
+        scanLineWeight = CalcScanLine(dy, in.filterWidth);
+        float signY = sign(dy);
+        dy = dy * dy;
+        dy = dy * dy;
+        dy *= 8.0;
+        dy /= uniforms.textureSize.y;
+        dy *= signY;
+        tc = float2(texcoord.x, yCoord + dy);
+    } else {
+        // Modo SHARPER
+        float2 tempCoord = floor(texcoordInPixels) + 0.5;
+        float2 coord = tempCoord / uniforms.textureSize;
+        float2 deltas = texcoordInPixels - tempCoord;
+        scanLineWeight = CalcScanLine(deltas.y, in.filterWidth);
+        float2 signs = sign(deltas);
+        deltas.x *= 2.0;
+        deltas = deltas * deltas;
+        deltas.y = deltas.y * deltas.y;
+        deltas.x *= 0.5;
+        deltas.y *= 8.0;
+        deltas /= uniforms.textureSize;
+        deltas *= signs;
+        tc = coord + deltas;
+    }
+
+    // Muestrear textura (texture() en GLSL = sample() en MSL)
+    float3 colour = colorTexture.sample(textureSampler, tc).rgb;
+
+    if (SCANLINES) {
+        if (GAMMA) {
+            if (FAKE_GAMMA) {
+                colour = colour * colour;
+            } else {
+                colour = pow(colour, float3(INPUT_GAMMA));
+            }
+        }
+        scanLineWeight *= BLOOM_FACTOR;
+        colour *= scanLineWeight;
+
+        if (GAMMA) {
+            if (FAKE_GAMMA) {
+                colour = sqrt(colour);
+            } else {
+                colour = pow(colour, float3(1.0 / OUTPUT_GAMMA));
+            }
+        }
+    }
+
+    // Aplicar máscara CRT
+    if (MASK_TYPE == 0) {
+        return float4(colour, 1.0);
+    } else if (MASK_TYPE == 1) {
+        // Máscara verde/magenta
+        float whichMask = fract(in.position.x * 0.5);
+        float3 mask;
+        if (whichMask < 0.5) {
+            mask = float3(MASK_BRIGHTNESS, 1.0, MASK_BRIGHTNESS);
+        } else {
+            mask = float3(1.0, MASK_BRIGHTNESS, 1.0);
+        }
+        return float4(colour * mask, 1.0);
+    } else if (MASK_TYPE == 2) {
+        // Máscara trinitron
+        float whichMask = fract(in.position.x * 0.3333333);
+        float3 mask = float3(MASK_BRIGHTNESS, MASK_BRIGHTNESS, MASK_BRIGHTNESS);
+        if (whichMask < 0.3333333) {
+            mask.x = 1.0;
+        } else if (whichMask < 0.6666666) {
+            mask.y = 1.0;
+        } else {
+            mask.z = 1.0;
+        }
+        return float4(colour * mask, 1.0);
+    }
+
+    return float4(colour, 1.0);
+}

data/shaders/crtpi_vertex.glsl

@@ -0,0 +1,48 @@
+#version 330 core
+
+// Configuración
+#define SCANLINES
+#define MULTISAMPLE
+#define GAMMA
+//#define FAKE_GAMMA
+//#define CURVATURE
+//#define SHARPER
+#define MASK_TYPE 2
+
+#define CURVATURE_X 0.05
+#define CURVATURE_Y 0.1
+#define MASK_BRIGHTNESS 0.80
+#define SCANLINE_WEIGHT 6.0
+#define SCANLINE_GAP_BRIGHTNESS 0.12
+#define BLOOM_FACTOR 3.5
+#define INPUT_GAMMA 2.4
+#define OUTPUT_GAMMA 2.2
+
+// Inputs (desde VAO)
+layout(location = 0) in vec2 aPosition;
+layout(location = 1) in vec2 aTexCoord;
+
+// Outputs al fragment shader
+out vec2 vTexCoord;
+out float vFilterWidth;
+#if defined(CURVATURE)
+out vec2 vScreenScale;
+#endif
+
+// Uniforms
+uniform vec2 TextureSize;
+
+void main()
+{
+#if defined(CURVATURE)
+	vScreenScale = vec2(1.0, 1.0);
+#endif
+	// Calcula filterWidth dinámicamente basándose en la altura de la textura
+	vFilterWidth = (768.0 / TextureSize.y) / 3.0;
+
+	// Pasar coordenadas de textura (invertir Y para SDL)
+	vTexCoord = vec2(aTexCoord.x, 1.0 - aTexCoord.y) * 1.0001;
+
+	// Posición del vértice (ya en espacio de clip [-1, 1])
+	gl_Position = vec4(aPosition, 0.0, 1.0);
+}

data/shaders/crtpi_vertex.metal

@@ -0,0 +1,46 @@
+//
+// CRT-Pi Vertex Shader - Metal Shading Language
+// Portado desde GLSL a MSL para macOS
+//
+
+#include <metal_stdlib>
+using namespace metal;
+
+// Estructura de entrada del vertex shader (desde el buffer de vértices)
+struct VertexIn {
+    float2 position [[attribute(0)]];  // Posición del vértice
+    float2 texCoord [[attribute(1)]];  // Coordenadas de textura
+};
+
+// Estructura de salida del vertex shader (entrada al fragment shader)
+struct VertexOut {
+    float4 position [[position]];      // Posición en clip space
+    float2 texCoord;                   // Coordenadas de textura
+    float filterWidth;                 // Ancho del filtro calculado
+    // float2 screenScale;             // Solo si CURVATURE está activo
+};
+
+// Uniforms (constantes del shader)
+struct Uniforms {
+    float2 textureSize;                // Tamaño de la textura (width, height)
+};
+
+// Entry point del vertex shader
+vertex VertexOut vertex_main(VertexIn in [[stage_in]],
+                             constant Uniforms& uniforms [[buffer(1)]]) {
+    VertexOut out;
+
+    // Posición del vértice (ya está en espacio de clip [-1, 1])
+    out.position = float4(in.position, 0.0, 1.0);
+
+    // Pasar coordenadas de textura (invertir Y para SDL, igual que en GLSL)
+    out.texCoord = float2(in.texCoord.x, 1.0 - in.texCoord.y) * 1.0001;
+
+    // Calcular filterWidth dinámicamente basándose en la altura de la textura
+    out.filterWidth = (768.0 / uniforms.textureSize.y) / 3.0;
+
+    // Si CURVATURE estuviera activo:
+    // out.screenScale = float2(1.0, 1.0);
+
+    return out;
+}

source/external/jail_shader.cpp

@@ -1,468 +0,0 @@
-#include "jail_shader.h"
-
-#include <SDL3/SDL.h>  // Para SDL_GL_GetProcAddress, SDL_LogError
-#include <stdint.h>    // Para uintptr_t
-#include <cstring>    // Para strncmp
-#include <stdexcept>  // Para runtime_error
-#include <vector>     // Para vector
-
-#ifdef __APPLE__
-#include <OpenGL/OpenGL.h>  // Para OpenGL en macOS
-
-#include "CoreFoundation/CoreFoundation.h"  // Para Core Foundation en macOS
-#if ESSENTIAL_GL_PRACTICES_SUPPORT_GL3
-#include <OpenGL/gl3.h>       // Para OpenGL 3 en macOS
-#else                         // NO ESSENTIAL_GL_PRACTICES_SUPPORT_GL3
-#include <OpenGL/gl.h>        // Para OpenGL (compatibilidad) en macOS
-#endif                        // ESSENTIAL_GL_PRACTICES_SUPPORT_GL3
-#else                         // SI NO ES __APPLE__
-#include <SDL3/SDL_opengl.h>  // Para GLuint, GLint, glTexCoord2f, glVertex2f
-#endif                        // __APPLE__
-
-namespace shader {
-// Constantes
-const GLuint INVALID_SHADER_ID = 0;
-const GLuint INVALID_PROGRAM_ID = 0;
-const GLuint DEFAULT_TEXTURE_ID = 1;
-
-// Variables globales
-SDL_Window *win = nullptr;
-SDL_Renderer *renderer = nullptr;
-GLuint programId = 0;
-SDL_Texture *backBuffer = nullptr;
-SDL_Point win_size = {320 * 4, 256 * 4};
-SDL_FPoint tex_size = {320, 256};
-bool usingOpenGL = false;
-
-#ifndef __APPLE__
-// Declaración de funciones de extensión de OpenGL (evitando GLEW)
-PFNGLCREATESHADERPROC glCreateShader;
-PFNGLSHADERSOURCEPROC glShaderSource;
-PFNGLCOMPILESHADERPROC glCompileShader;
-PFNGLGETSHADERIVPROC glGetShaderiv;
-PFNGLGETSHADERINFOLOGPROC glGetShaderInfoLog;
-PFNGLDELETESHADERPROC glDeleteShader;
-PFNGLATTACHSHADERPROC glAttachShader;
-PFNGLCREATEPROGRAMPROC glCreateProgram;
-PFNGLLINKPROGRAMPROC glLinkProgram;
-PFNGLVALIDATEPROGRAMPROC glValidateProgram;
-PFNGLGETPROGRAMIVPROC glGetProgramiv;
-PFNGLGETPROGRAMINFOLOGPROC glGetProgramInfoLog;
-PFNGLUSEPROGRAMPROC glUseProgram;
-PFNGLDELETEPROGRAMPROC glDeleteProgram;
-PFNGLGETUNIFORMLOCATIONPROC glGetUniformLocation;
-PFNGLUNIFORM2FPROC glUniform2f;
-
-bool initGLExtensions() {
-    glCreateShader = (PFNGLCREATESHADERPROC)SDL_GL_GetProcAddress("glCreateShader");
-    glShaderSource = (PFNGLSHADERSOURCEPROC)SDL_GL_GetProcAddress("glShaderSource");
-    glCompileShader = (PFNGLCOMPILESHADERPROC)SDL_GL_GetProcAddress("glCompileShader");
-    glGetShaderiv = (PFNGLGETSHADERIVPROC)SDL_GL_GetProcAddress("glGetShaderiv");
-    glGetShaderInfoLog = (PFNGLGETSHADERINFOLOGPROC)SDL_GL_GetProcAddress("glGetShaderInfoLog");
-    glDeleteShader = (PFNGLDELETESHADERPROC)SDL_GL_GetProcAddress("glDeleteShader");
-    glAttachShader = (PFNGLATTACHSHADERPROC)SDL_GL_GetProcAddress("glAttachShader");
-    glCreateProgram = (PFNGLCREATEPROGRAMPROC)SDL_GL_GetProcAddress("glCreateProgram");
-    glLinkProgram = (PFNGLLINKPROGRAMPROC)SDL_GL_GetProcAddress("glLinkProgram");
-    glValidateProgram = (PFNGLVALIDATEPROGRAMPROC)SDL_GL_GetProcAddress("glValidateProgram");
-    glGetProgramiv = (PFNGLGETPROGRAMIVPROC)SDL_GL_GetProcAddress("glGetProgramiv");
-    glGetProgramInfoLog = (PFNGLGETPROGRAMINFOLOGPROC)SDL_GL_GetProcAddress("glGetProgramInfoLog");
-    glUseProgram = (PFNGLUSEPROGRAMPROC)SDL_GL_GetProcAddress("glUseProgram");
-    glDeleteProgram = (PFNGLDELETEPROGRAMPROC)SDL_GL_GetProcAddress("glDeleteProgram");
-    glGetUniformLocation = (PFNGLGETUNIFORMLOCATIONPROC)SDL_GL_GetProcAddress("glGetUniformLocation");
-    glUniform2f = (PFNGLUNIFORM2FPROC)SDL_GL_GetProcAddress("glUniform2f");
-
-    return glCreateShader && glShaderSource && glCompileShader && glGetShaderiv &&
-        glGetShaderInfoLog && glDeleteShader && glAttachShader && glCreateProgram &&
-        glLinkProgram && glValidateProgram && glGetProgramiv && glGetProgramInfoLog &&
-        glUseProgram && glDeleteProgram && glGetUniformLocation && glUniform2f;
-}
-#endif
-
-// Función para verificar errores de OpenGL
-void checkGLError(const char *operation) {
-    GLenum error = glGetError();
-    if (error != GL_NO_ERROR) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
-            "Error OpenGL en %s: 0x%x",
-            operation,
-            error);
-    }
-}
-
-// Función para compilar un shader a partir de un std::string
-GLuint compileShader(const std::string &source, GLuint shader_type) {
-    if (source.empty()) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "ERROR FATAL: El código fuente del shader está vacío.");
-        throw std::runtime_error("ERROR FATAL: El código fuente del shader está vacío.");
-    }
-
-    // Crear identificador del shader
-    GLuint shader_id = glCreateShader(shader_type);
-    if (shader_id == INVALID_SHADER_ID) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error al crear el shader.");
-        checkGLError("glCreateShader");
-        return INVALID_SHADER_ID;
-    }
-
-    // Agregar una directiva según el tipo de shader
-    std::string directive = (shader_type == GL_VERTEX_SHADER)
-        ? "#define VERTEX\n"
-        : "#define FRAGMENT\n";
-
-    const char *sources[2] = {directive.c_str(), source.c_str()};
-
-    // Especificar el código fuente del shader
-    glShaderSource(shader_id, 2, sources, nullptr);
-    checkGLError("glShaderSource");
-
-    // Compilar el shader
-    glCompileShader(shader_id);
-    checkGLError("glCompileShader");
-
-    // Verificar si la compilación fue exitosa
-    GLint compiled_ok = GL_FALSE;
-    glGetShaderiv(shader_id, GL_COMPILE_STATUS, &compiled_ok);
-    if (compiled_ok != GL_TRUE) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error en la compilación del shader (%d)!", shader_id);
-        GLint log_length;
-        glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &log_length);
-        if (log_length > 0) {
-            std::vector<GLchar> log(log_length);
-            glGetShaderInfoLog(shader_id, log_length, &log_length, log.data());
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Registro de compilación del shader: %s", log.data());
-        }
-        glDeleteShader(shader_id);
-        return INVALID_SHADER_ID;
-    }
-    return shader_id;
-}
-
-// Función para compilar un programa de shaders (vertex y fragment) a partir de std::string
-GLuint compileProgram(const std::string &vertex_shader_source, const std::string &fragment_shader_source) {
-    GLuint program_id = glCreateProgram();
-    if (program_id == INVALID_PROGRAM_ID) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error al crear el programa de shaders.");
-        checkGLError("glCreateProgram");
-        return INVALID_PROGRAM_ID;
-    }
-
-    // Si el fragment shader está vacío, reutilizamos el código del vertex shader
-    GLuint vertex_shader_id = compileShader(vertex_shader_source, GL_VERTEX_SHADER);
-    GLuint fragment_shader_id = compileShader(fragment_shader_source.empty() ? vertex_shader_source : fragment_shader_source, GL_FRAGMENT_SHADER);
-
-    if (vertex_shader_id != INVALID_SHADER_ID && fragment_shader_id != INVALID_SHADER_ID) {
-        // Asociar los shaders al programa
-        glAttachShader(program_id, vertex_shader_id);
-        checkGLError("glAttachShader vertex");
-        glAttachShader(program_id, fragment_shader_id);
-        checkGLError("glAttachShader fragment");
-
-        glLinkProgram(program_id);
-        checkGLError("glLinkProgram");
-
-        // Verificar el estado del enlace
-        GLint isLinked = GL_FALSE;
-        glGetProgramiv(program_id, GL_LINK_STATUS, &isLinked);
-        if (isLinked == GL_FALSE) {
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error al enlazar el programa de shaders.");
-            GLint log_length;
-            glGetProgramiv(program_id, GL_INFO_LOG_LENGTH, &log_length);
-            if (log_length > 0) {
-                std::vector<char> log(log_length);
-                glGetProgramInfoLog(program_id, log_length, &log_length, log.data());
-                SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Registro de enlace del programa: %s", log.data());
-            }
-            glDeleteProgram(program_id);
-            program_id = INVALID_PROGRAM_ID;
-        } else {
-            glValidateProgram(program_id);
-            checkGLError("glValidateProgram");
-
-            // Log de información del programa (solo si hay información)
-            GLint log_length;
-            glGetProgramiv(program_id, GL_INFO_LOG_LENGTH, &log_length);
-            if (log_length > 1)  // > 1 porque algunos drivers devuelven 1 para cadena vacía
-            {
-                std::vector<char> log(log_length);
-                glGetProgramInfoLog(program_id, log_length, &log_length, log.data());
-                SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Registro de información del programa:\n%s", log.data());
-            }
-        }
-    } else {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error: No se pudieron compilar los shaders.");
-        glDeleteProgram(program_id);
-        program_id = INVALID_PROGRAM_ID;
-    }
-
-    // Limpiar los shaders (ya no son necesarios después del enlace)
-    if (vertex_shader_id != INVALID_SHADER_ID) {
-        glDeleteShader(vertex_shader_id);
-    }
-    if (fragment_shader_id != INVALID_SHADER_ID) {
-        glDeleteShader(fragment_shader_id);
-    }
-
-    return program_id;
-}
-
-// Función para obtener el ID de textura OpenGL desde SDL3
-GLuint getTextureID(SDL_Texture *texture) {
-    if (!texture)
-        return DEFAULT_TEXTURE_ID;
-
-    // Intentar obtener el ID de textura OpenGL desde las propiedades de SDL3
-    SDL_PropertiesID props = SDL_GetTextureProperties(texture);
-    GLuint textureId = 0;
-
-    // Intentar diferentes nombres de propiedades según la versión de SDL3
-    textureId = (GLuint)(uintptr_t)SDL_GetPointerProperty(props, "SDL.texture.opengl.texture", nullptr);
-
-    // Si la primera no funciona, intentar con el nombre alternativo
-    if (textureId == 0) {
-        textureId = (GLuint)(uintptr_t)SDL_GetPointerProperty(props, "texture.opengl.texture", nullptr);
-    }
-
-    // Si aún no funciona, intentar obtener como número
-    if (textureId == 0) {
-        textureId = (GLuint)SDL_GetNumberProperty(props, "SDL.texture.opengl.texture", DEFAULT_TEXTURE_ID);
-    }
-
-    // Si ninguna funciona, usar el método manual de bindeo de textura
-    if (textureId == 0) {
-        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
-            "No se pudo obtener el ID de textura OpenGL, usando ID por defecto (%d)",
-            DEFAULT_TEXTURE_ID);
-        textureId = DEFAULT_TEXTURE_ID;
-    }
-
-    return textureId;
-}
-
-bool init(SDL_Window *window, SDL_Texture *back_buffer_texture, const std::string &vertex_shader, const std::string &fragment_shader) {
-    shader::win = window;
-    shader::renderer = SDL_GetRenderer(window);
-    shader::backBuffer = back_buffer_texture;
-
-    if (!shader::renderer) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error: No se pudo obtener el renderer de la ventana.");
-        return false;
-    }
-
-    SDL_GetWindowSize(window, &win_size.x, &win_size.y);
-    SDL_GetTextureSize(back_buffer_texture, &tex_size.x, &tex_size.y);
-
-    const auto render_name = SDL_GetRendererName(renderer);
-    if (!render_name) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error: No se pudo obtener el nombre del renderer.");
-        return false;
-    }
-
-    // Limpiar shader anterior si existe
-    if (programId != INVALID_PROGRAM_ID) {
-        glDeleteProgram(programId);
-        programId = INVALID_PROGRAM_ID;
-    }
-
-    // Verificar que el renderer sea OpenGL
-    if (!strncmp(render_name, "opengl", 6)) {
-#ifndef __APPLE__
-        if (!initGLExtensions()) {
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "ERROR: No se han podido inicializar las extensiones de OpenGL.");
-            usingOpenGL = false;
-            return false;
-        }
-#endif
-        // Compilar el programa de shaders utilizando std::string
-        programId = compileProgram(vertex_shader, fragment_shader);
-        if (programId == INVALID_PROGRAM_ID) {
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "ERROR: No se pudo compilar el programa de shaders.");
-            usingOpenGL = false;
-            return false;
-        }
-
-        // Establecer el uniform TextureSize inmediatamente después de compilar
-        // Los uniforms persisten en el programa una vez establecidos
-        glUseProgram(programId);
-        GLint textureSizeLocation = glGetUniformLocation(programId, "TextureSize");
-        if (textureSizeLocation != -1) {
-            glUniform2f(textureSizeLocation, tex_size.x, tex_size.y);
-            checkGLError("glUniform2f(TextureSize) - init");
-        } else {
-            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
-                "Warning: No se pudo encontrar el uniform 'TextureSize' en el shader");
-        }
-        glUseProgram(0);  // Deseleccionar el programa
-    } else {
-        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "ADVERTENCIA: El driver del renderer no es OpenGL (%s).", render_name);
-        usingOpenGL = false;
-        return false;
-    }
-
-    usingOpenGL = true;
-    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "** Shader system initialized successfully");
-    return true;
-}
-
-void render() {
-    // Establece el color de fondo
-    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
-    SDL_SetRenderTarget(renderer, nullptr);
-    SDL_RenderClear(renderer);
-
-    if (usingOpenGL && programId != INVALID_PROGRAM_ID) {
-        // Obtener el tamaño actual de la ventana (puede haber cambiado desde init)
-        int current_win_width, current_win_height;
-        SDL_GetWindowSize(win, &current_win_width, &current_win_height);
-
-        // Guardar estados de OpenGL
-        GLint oldProgramId;
-        glGetIntegerv(GL_CURRENT_PROGRAM, &oldProgramId);
-
-        GLint oldViewport[4];
-        glGetIntegerv(GL_VIEWPORT, oldViewport);
-
-        GLboolean wasTextureEnabled = glIsEnabled(GL_TEXTURE_2D);
-        GLint oldTextureId;
-        glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldTextureId);
-
-        // Obtener y bindear la textura
-        GLuint textureId = getTextureID(backBuffer);
-        glEnable(GL_TEXTURE_2D);
-        glBindTexture(GL_TEXTURE_2D, textureId);
-        checkGLError("glBindTexture");
-
-        // Usar nuestro programa de shaders
-        glUseProgram(programId);
-        checkGLError("glUseProgram");
-
-        // Recupera el tamaño lógico configurado con SDL_RenderSetLogicalSize
-        int logicalW, logicalH;
-        SDL_RendererLogicalPresentation mode;
-        SDL_GetRenderLogicalPresentation(renderer, &logicalW, &logicalH, &mode);
-        if (logicalW == 0 || logicalH == 0) {
-            logicalW = current_win_width;
-            logicalH = current_win_height;
-        }
-
-        // Cálculo del viewport
-        int viewportX = 0, viewportY = 0, viewportW = current_win_width, viewportH = current_win_height;
-        const bool USE_INTEGER_SCALE = mode == SDL_LOGICAL_PRESENTATION_INTEGER_SCALE;
-        if (USE_INTEGER_SCALE) {
-            // Calcula el factor de escalado entero máximo que se puede aplicar
-            int scaleX = current_win_width / logicalW;
-            int scaleY = current_win_height / logicalH;
-            int scale = (scaleX < scaleY ? scaleX : scaleY);
-            if (scale < 1) {
-                scale = 1;
-            }
-            viewportW = logicalW * scale;
-            viewportH = logicalH * scale;
-            viewportX = (current_win_width - viewportW) / 2;
-            viewportY = (current_win_height - viewportH) / 2;
-        } else {
-            // Letterboxing: preserva la relación de aspecto usando una escala flotante
-            float windowAspect = static_cast<float>(current_win_width) / current_win_height;
-            float logicalAspect = static_cast<float>(logicalW) / logicalH;
-            if (windowAspect > logicalAspect) {
-                viewportW = static_cast<int>(logicalAspect * current_win_height);
-                viewportX = (current_win_width - viewportW) / 2;
-            } else {
-                viewportH = static_cast<int>(current_win_width / logicalAspect);
-                viewportY = (current_win_height - viewportH) / 2;
-            }
-        }
-        glViewport(viewportX, viewportY, viewportW, viewportH);
-        checkGLError("glViewport");
-
-        // Configurar la proyección ortográfica usando el espacio lógico
-        glMatrixMode(GL_PROJECTION);
-        glLoadIdentity();
-
-        // Queremos que el origen esté en la esquina superior izquierda del espacio lógico.
-        glOrtho(0, static_cast<GLdouble>(logicalW), static_cast<GLdouble>(logicalH), 0, -1, 1);
-        glMatrixMode(GL_MODELVIEW);
-        glLoadIdentity();
-
-        // Dibuja el quad con las coordenadas ajustadas.
-        // Se asignan las coordenadas de textura "normales" para que no quede espejado horizontalmente,
-        // y se mantiene el flip vertical para que la imagen no aparezca volteada.
-        glBegin(GL_TRIANGLE_STRIP);
-        // Vértice superior izquierdo
-        glTexCoord2f(0.0f, 1.0f);
-        glVertex2f(0.0f, 0.0f);
-        // Vértice superior derecho
-        glTexCoord2f(1.0f, 1.0f);
-        glVertex2f(static_cast<GLfloat>(logicalW), 0.0f);
-        // Vértice inferior izquierdo
-        glTexCoord2f(0.0f, 0.0f);
-        glVertex2f(0.0f, static_cast<GLfloat>(logicalH));
-        // Vértice inferior derecho
-        glTexCoord2f(1.0f, 0.0f);
-        glVertex2f(static_cast<GLfloat>(logicalW), static_cast<GLfloat>(logicalH));
-        glEnd();
-        checkGLError("render quad");
-
-        SDL_GL_SwapWindow(win);
-
-        // Restaurar estados de OpenGL
-        glUseProgram(oldProgramId);
-        glBindTexture(GL_TEXTURE_2D, oldTextureId);
-        if (!wasTextureEnabled) {
-            glDisable(GL_TEXTURE_2D);
-        }
-        glViewport(oldViewport[0], oldViewport[1], oldViewport[2], oldViewport[3]);
-    } else {
-        // Fallback a renderizado normal de SDL
-        SDL_RenderTexture(renderer, backBuffer, nullptr, nullptr);
-        SDL_RenderPresent(renderer);
-    }
-}
-
-void setTextureSize(float width, float height) {
-    if (!usingOpenGL || programId == INVALID_PROGRAM_ID) {
-        return;
-    }
-
-    // Guardar el programa actual
-    GLint oldProgramId;
-    glGetIntegerv(GL_CURRENT_PROGRAM, &oldProgramId);
-
-    // Usar nuestro programa
-    glUseProgram(programId);
-
-    // Obtener la ubicación del uniform TextureSize
-    GLint textureSizeLocation = glGetUniformLocation(programId, "TextureSize");
-    if (textureSizeLocation != -1) {
-        glUniform2f(textureSizeLocation, width, height);
-        checkGLError("glUniform2f(TextureSize)");
-    } else {
-        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
-            "Warning: No se pudo encontrar el uniform 'TextureSize' en el shader");
-    }
-
-    // Restaurar el programa anterior
-    glUseProgram(oldProgramId);
-}
-
-void cleanup() {
-    if (programId != INVALID_PROGRAM_ID) {
-        glDeleteProgram(programId);
-        programId = INVALID_PROGRAM_ID;
-        SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Programa de shaders liberado.");
-    }
-
-    // Reinicializar variables
-    win = nullptr;
-    renderer = nullptr;
-    backBuffer = nullptr;
-    usingOpenGL = false;
-}
-
-bool isUsingOpenGL() {
-    return usingOpenGL;
-}
-
-GLuint getProgramId() {
-    return programId;
-}
-}  // namespace shader

source/external/jail_shader.h

@@ -1,10 +0,0 @@
-#pragma once
-
-#include <SDL3/SDL.h>  // Para SDL_Texture, SDL_Window
-#include <string>  // Para basic_string, string
-
-namespace shader {
-bool init(SDL_Window *ventana, SDL_Texture *texturaBackBuffer, const std::string &vertexShader, const std::string &fragmentShader = "");
-void render();
-void setTextureSize(float width, float height);  // Establece el tamaño de textura como uniform
-}  // namespace shader

source/rendering/metal/METAL_BACKEND_NOTES.md

@@ -0,0 +1,166 @@
+# Metal Shader Backend - Notas de Implementación
+
+## Estado Actual
+
+✅ **Completado:**
+- Shaders MSL (Metal Shading Language) portados desde GLSL
+- Estructura básica de `MetalShader` class
+- Inicialización de Metal device y command queue
+- Compilación de shaders en runtime
+- Creación de pipeline state
+- Buffers de vértices, índices y uniforms
+
+❌ **Pendiente:**
+- **Render loop completo** (la parte más crítica)
+- Obtener textura Metal desde SDL_Texture
+- Gestión de drawables y presentation
+
+## Diferencias GLSL vs MSL
+
+| Concepto | GLSL (OpenGL) | MSL (Metal) |
+|----------|---------------|-------------|
+| Entrada vertex | `layout(location = 0) in vec2` | `[[attribute(0)]]` |
+| Salida vertex | `out vec2` | Struct con `[[position]]` |
+| Uniforms | `uniform vec2` | `constant` struct en `[[buffer(N)]]` |
+| Sampling | `texture(sampler2D, vec2)` | `texture.sample(sampler, float2)` |
+| Entry point | `void main()` | `vertex/fragment function_name()` |
+| Vector types | `vec2, vec3, vec4` | `float2, float3, float4` |
+
+## Pasos para Completar el Render Loop
+
+El método `MetalShader::render()` necesita:
+
+```objc
+1. Obtener drawable del CAMetalLayer:
+   id<CAMetalDrawable> drawable = [metal_layer_ nextDrawable];
+
+2. Crear command buffer:
+   id<MTLCommandBuffer> command_buffer = [command_queue_ commandBuffer];
+
+3. Crear render pass descriptor:
+   MTLRenderPassDescriptor* pass_descriptor = [MTLRenderPassDescriptor renderPassDescriptor];
+   pass_descriptor.colorAttachments[0].texture = drawable.texture;
+   pass_descriptor.colorAttachments[0].loadAction = MTLLoadActionClear;
+   pass_descriptor.colorAttachments[0].storeAction = MTLStoreActionStore;
+   pass_descriptor.colorAttachments[0].clearColor = MTLClearColorMake(0, 0, 0, 1);
+
+4. Crear render command encoder:
+   id<MTLRenderCommandEncoder> encoder =
+       [command_buffer renderCommandEncoderWithDescriptor:pass_descriptor];
+
+5. Configurar pipeline y buffers:
+   [encoder setRenderPipelineState:pipeline_state_];
+   [encoder setVertexBuffer:vertex_buffer_ offset:0 atIndex:0];
+   [encoder setVertexBuffer:uniforms_buffer_ offset:0 atIndex:1];
+   [encoder setFragmentBuffer:uniforms_buffer_ offset:0 atIndex:1];
+   [encoder setFragmentTexture:game_texture offset:0 atIndex:0];
+   [encoder setFragmentSamplerState:sampler_state_ atIndex:0];
+
+6. Dibujar:
+   [encoder drawIndexedPrimitives:MTLPrimitiveTypeTriangle
+                       indexCount:6
+                        indexType:MTLIndexTypeUInt16
+                      indexBuffer:index_buffer_
+                indexBufferOffset:0];
+
+7. Finalizar:
+   [encoder endEncoding];
+   [command_buffer presentDrawable:drawable];
+   [command_buffer commit];
+```
+
+## Problema Crítico: Obtener MTLTexture desde SDL_Texture
+
+SDL3 renderiza el juego a `back_buffer_` (SDL_Texture). Necesitamos obtener
+la textura Metal subyacente para pasarla al fragment shader.
+
+**Opciones:**
+
+1. **SDL_GetProperty()** - Usar SDL3 properties system:
+   ```cpp
+   id<MTLTexture> metal_texture = (__bridge id<MTLTexture>)SDL_GetProperty(
+       SDL_GetTextureProperties(back_buffer_),
+       "SDL.texture.metal.texture",
+       nullptr
+   );
+   ```
+
+2. **Render to Metal texture directamente** - En lugar de usar SDL_Texture,
+   crear una MTLTexture directamente y renderizar el juego ahí. Más trabajo
+   pero más control.
+
+3. **Copiar SDL texture a Metal texture** - Menos eficiente pero más simple.
+
+## Sampler State
+
+Falta crear el sampler state (equivalente a glTexParameteri en OpenGL):
+
+```objc
+MTLSamplerDescriptor* sampler_descriptor = [[MTLSamplerDescriptor alloc] init];
+sampler_descriptor.minFilter = MTLSamplerMinMagFilterLinear;
+sampler_descriptor.magFilter = MTLSamplerMinMagFilterLinear;
+sampler_descriptor.sAddressMode = MTLSamplerAddressModeClampToEdge;
+sampler_descriptor.tAddressMode = MTLSamplerAddressModeClampToEdge;
+
+id<MTLSamplerState> sampler_state = [device_ newSamplerStateWithDescriptor:sampler_descriptor];
+```
+
+## Build Configuration
+
+Para compilar en Xcode/CMake, necesitarás:
+
+1. **CMakeLists.txt** - Añadir metal_shader.mm:
+   ```cmake
+   if(APPLE)
+       set(RENDERING_SOURCES
+           ${RENDERING_SOURCES}
+           source/rendering/metal/metal_shader.mm
+       )
+       target_link_libraries(${PROJECT_NAME}
+           "-framework Metal"
+           "-framework QuartzCore"
+       )
+   endif()
+   ```
+
+2. **Compilar shaders .metal** - Opcionalmente pre-compilar:
+   ```bash
+   xcrun -sdk macosx metal -c crtpi_vertex.metal -o crtpi_vertex.air
+   xcrun -sdk macosx metal -c crtpi_fragment.metal -o crtpi_fragment.air
+   xcrun -sdk macosx metallib crtpi_*.air -o crtpi.metallib
+   ```
+
+3. **Cargar .metallib** en código:
+   ```objc
+   NSString* path = [[NSBundle mainBundle] pathForResource:@"crtpi" ofType:@"metallib"];
+   id<MTLLibrary> library = [device_ newLibraryWithFile:path error:&error];
+   ```
+
+## Testing en macOS
+
+Cuando pruebes en macOS:
+
+1. Verifica que `SDL_WINDOW_METAL` está activo en screen.cpp
+2. Compila con `-DCMAKE_BUILD_TYPE=Debug` para ver logs
+3. Usa Xcode Instruments (Metal Debugger) para inspeccionar frames
+4. Compara rendimiento con/sin shaders
+
+## Referencias Útiles
+
+- [Metal Programming Guide](https://developer.apple.com/metal/)
+- [Metal Shading Language Specification](https://developer.apple.com/metal/Metal-Shading-Language-Specification.pdf)
+- [SDL3 Metal Integration](https://github.com/libsdl-org/SDL/blob/main/docs/README-metal.md)
+
+## Próximos Pasos
+
+1. Implementar `render()` completo
+2. Resolver obtención de textura desde SDL
+3. Crear sampler state
+4. Testear en macOS real
+5. Optimizar si es necesario (probablemente ya será rápido)
+
+---
+
+**Nota importante**: Metal es significativamente más verboso que OpenGL pero
+también más eficiente. Una vez que funcione el render loop, el rendimiento
+debería ser excelente en macOS.

source/rendering/metal/metal_shader.h

@@ -0,0 +1,76 @@
+#pragma once
+
+#include "../shader_backend.h"
+
+#ifdef __APPLE__
+
+#import <Metal/Metal.h>
+#import <QuartzCore/CAMetalLayer.h>
+
+namespace Rendering {
+
+/**
+ * @brief Backend de shaders usando Metal para macOS
+ *
+ * Implementa el renderizado de shaders usando Metal API nativo de Apple:
+ * - MTLDevice para acceso a GPU
+ * - MTLRenderPipelineState para configuración del pipeline
+ * - MTLCommandQueue para enviar comandos a GPU
+ * - MSL (Metal Shading Language) para shaders
+ */
+class MetalShader : public ShaderBackend {
+public:
+    MetalShader() = default;
+    ~MetalShader() override;
+
+    bool init(SDL_Window* window,
+             SDL_Texture* texture,
+             const std::string& vertex_source,
+             const std::string& fragment_source) override;
+
+    void render() override;
+    void setTextureSize(float width, float height) override;
+    void cleanup() override;
+    bool isHardwareAccelerated() const override { return is_initialized_; }
+
+private:
+    // Funciones auxiliares
+    bool createMetalDevice();
+    bool compileShaders(const std::string& vertex_source,
+                       const std::string& fragment_source);
+    bool createPipeline();
+    bool createBuffers();
+    id<MTLTexture> getMetalTexture(SDL_Texture* texture);
+
+    // Estado SDL
+    SDL_Window* window_ = nullptr;
+    SDL_Renderer* renderer_ = nullptr;
+    SDL_Texture* back_buffer_ = nullptr;
+
+    // Estado Metal
+    id<MTLDevice> device_ = nil;                          // GPU device
+    id<MTLCommandQueue> command_queue_ = nil;             // Cola de comandos
+    id<MTLRenderPipelineState> pipeline_state_ = nil;     // Estado del pipeline
+    id<MTLBuffer> vertex_buffer_ = nil;                   // Buffer de vértices
+    id<MTLBuffer> index_buffer_ = nil;                    // Buffer de índices
+    id<MTLBuffer> uniforms_buffer_ = nil;                 // Buffer de uniforms
+    CAMetalLayer* metal_layer_ = nil;                     // Layer de Metal
+
+    // Uniforms
+    struct Uniforms {
+        float textureSize[2];  // width, height
+    } uniforms_;
+
+    // Tamaños
+    int window_width_ = 0;
+    int window_height_ = 0;
+    float texture_width_ = 0.0f;
+    float texture_height_ = 0.0f;
+
+    // Estado
+    bool is_initialized_ = false;
+};
+
+} // namespace Rendering
+
+#endif // __APPLE__

source/rendering/metal/metal_shader.mm

@@ -0,0 +1,301 @@
+// Usar .mm (Objective-C++) en lugar de .cpp para código Metal en macOS
+
+#include "metal_shader.h"
+
+#ifdef __APPLE__
+
+#import <SDL3/SDL.h>
+#import <SDL3/SDL_metal.h>
+#include <vector>
+
+namespace Rendering {
+
+MetalShader::~MetalShader() {
+    cleanup();
+}
+
+bool MetalShader::createMetalDevice() {
+    // Obtener el device Metal por defecto (GPU del sistema)
+    device_ = MTLCreateSystemDefaultDevice();
+    if (!device_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: No se pudo crear Metal device");
+        return false;
+    }
+
+    // Crear command queue
+    command_queue_ = [device_ newCommandQueue];
+    if (!command_queue_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: No se pudo crear Metal command queue");
+        return false;
+    }
+
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+               "Metal device creado: %s", [[device_ name] UTF8String]);
+
+    return true;
+}
+
+bool MetalShader::compileShaders(const std::string& vertex_source,
+                                const std::string& fragment_source) {
+    // En Metal, los shaders se pueden compilar de dos formas:
+    // 1. Runtime compilation desde strings (lo que haremos aquí)
+    // 2. Pre-compilados a .metallib (más eficiente pero requiere build step)
+
+    NSError* error = nil;
+
+    // Convertir sources a NSString
+    NSString* vertex_code = [NSString stringWithUTF8String:vertex_source.c_str()];
+    NSString* fragment_code = [NSString stringWithUTF8String:fragment_source.c_str()];
+
+    // Combinar vertex + fragment en un solo source (Metal permite múltiples shaders por library)
+    NSString* combined_source = [NSString stringWithFormat:@"%@\n\n%@",
+                                 vertex_code, fragment_code];
+
+    // Crear library desde source code
+    id<MTLLibrary> library = [device_ newLibraryWithSource:combined_source
+                                                   options:nil
+                                                     error:&error];
+    if (!library) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: Fallo al compilar shaders Metal: %s",
+                    [[error localizedDescription] UTF8String]);
+        return false;
+    }
+
+    // Obtener funciones del library
+    id<MTLFunction> vertex_function = [library newFunctionWithName:@"vertex_main"];
+    id<MTLFunction> fragment_function = [library newFunctionWithName:@"fragment_main"];
+
+    if (!vertex_function || !fragment_function) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: No se encontraron las funciones vertex_main o fragment_main");
+        return false;
+    }
+
+    // Crear pipeline descriptor
+    MTLRenderPipelineDescriptor* pipeline_descriptor = [[MTLRenderPipelineDescriptor alloc] init];
+    pipeline_descriptor.vertexFunction = vertex_function;
+    pipeline_descriptor.fragmentFunction = fragment_function;
+
+    // Configurar formato de color (BGRA8Unorm es común en macOS)
+    pipeline_descriptor.colorAttachments[0].pixelFormat = MTLPixelFormatBGRA8Unorm;
+
+    // Configurar vertex descriptor (cómo están organizados los vértices)
+    MTLVertexDescriptor* vertex_descriptor = [[MTLVertexDescriptor alloc] init];
+
+    // Atributo 0: position (2 floats)
+    vertex_descriptor.attributes[0].format = MTLVertexFormatFloat2;
+    vertex_descriptor.attributes[0].offset = 0;
+    vertex_descriptor.attributes[0].bufferIndex = 0;
+
+    // Atributo 1: texCoord (2 floats)
+    vertex_descriptor.attributes[1].format = MTLVertexFormatFloat2;
+    vertex_descriptor.attributes[1].offset = 2 * sizeof(float);
+    vertex_descriptor.attributes[1].bufferIndex = 0;
+
+    // Layout del buffer (stride = 4 floats por vértice)
+    vertex_descriptor.layouts[0].stride = 4 * sizeof(float);
+    vertex_descriptor.layouts[0].stepRate = 1;
+    vertex_descriptor.layouts[0].stepFunction = MTLVertexStepFunctionPerVertex;
+
+    pipeline_descriptor.vertexDescriptor = vertex_descriptor;
+
+    // Crear pipeline state
+    pipeline_state_ = [device_ newRenderPipelineStateWithDescriptor:pipeline_descriptor
+                                                              error:&error];
+    if (!pipeline_state_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: Fallo al crear pipeline state: %s",
+                    [[error localizedDescription] UTF8String]);
+        return false;
+    }
+
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+               "Shaders Metal compilados correctamente");
+
+    return true;
+}
+
+bool MetalShader::createBuffers() {
+    // Crear quad de pantalla completa (igual que en OpenGL)
+    // Formato: x, y, u, v
+    float vertices[] = {
+        -1.0f, -1.0f,    0.0f, 0.0f,  // Inferior izquierda
+         1.0f, -1.0f,    1.0f, 0.0f,  // Inferior derecha
+         1.0f,  1.0f,    1.0f, 1.0f,  // Superior derecha
+        -1.0f,  1.0f,    0.0f, 1.0f   // Superior izquierda
+    };
+
+    uint16_t indices[] = {
+        0, 1, 2,  // Primer triángulo
+        2, 3, 0   // Segundo triángulo
+    };
+
+    // Crear vertex buffer
+    vertex_buffer_ = [device_ newBufferWithBytes:vertices
+                                          length:sizeof(vertices)
+                                         options:MTLResourceStorageModeShared];
+    if (!vertex_buffer_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: Fallo al crear vertex buffer");
+        return false;
+    }
+
+    // Crear index buffer
+    index_buffer_ = [device_ newBufferWithBytes:indices
+                                         length:sizeof(indices)
+                                        options:MTLResourceStorageModeShared];
+    if (!index_buffer_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: Fallo al crear index buffer");
+        return false;
+    }
+
+    // Crear uniforms buffer
+    uniforms_buffer_ = [device_ newBufferWithLength:sizeof(Uniforms)
+                                            options:MTLResourceStorageModeShared];
+    if (!uniforms_buffer_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: Fallo al crear uniforms buffer");
+        return false;
+    }
+
+    return true;
+}
+
+bool MetalShader::init(SDL_Window* window,
+                      SDL_Texture* texture,
+                      const std::string& vertex_source,
+                      const std::string& fragment_source) {
+    window_ = window;
+    back_buffer_ = texture;
+    renderer_ = SDL_GetRenderer(window);
+
+    if (!renderer_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: No se pudo obtener el renderer");
+        return false;
+    }
+
+    // Verificar que es Metal renderer
+    const char* renderer_name = SDL_GetRendererName(renderer_);
+    if (!renderer_name || strncmp(renderer_name, "metal", 5) != 0) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                   "Renderer no es Metal: %s", renderer_name ? renderer_name : "unknown");
+        return false;
+    }
+
+    // Obtener tamaños
+    SDL_GetWindowSize(window_, &window_width_, &window_height_);
+    SDL_GetTextureSize(back_buffer_, &texture_width_, &texture_height_);
+
+    // Crear Metal device
+    if (!createMetalDevice()) {
+        return false;
+    }
+
+    // Compilar shaders
+    if (!compileShaders(vertex_source, fragment_source)) {
+        return false;
+    }
+
+    // Crear buffers
+    if (!createBuffers()) {
+        return false;
+    }
+
+    // Inicializar uniforms
+    uniforms_.textureSize[0] = texture_width_;
+    uniforms_.textureSize[1] = texture_height_;
+
+    // Copiar uniforms al buffer
+    memcpy([uniforms_buffer_ contents], &uniforms_, sizeof(Uniforms));
+
+    // Obtener Metal layer de SDL
+    metal_layer_ = (__bridge CAMetalLayer*)SDL_GetProperty(
+        SDL_GetWindowProperties(window_),
+        SDL_PROP_WINDOW_METAL_LAYER_POINTER,
+        nullptr
+    );
+
+    if (!metal_layer_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: No se pudo obtener Metal layer");
+        return false;
+    }
+
+    metal_layer_.device = device_;
+    metal_layer_.pixelFormat = MTLPixelFormatBGRA8Unorm;
+
+    is_initialized_ = true;
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+               "** Metal Shader Backend inicializado correctamente");
+
+    return true;
+}
+
+void MetalShader::render() {
+    if (!is_initialized_ || !pipeline_state_) {
+        // Fallback a renderizado normal
+        SDL_SetRenderDrawColor(renderer_, 0, 0, 0, 255);
+        SDL_SetRenderTarget(renderer_, nullptr);
+        SDL_RenderClear(renderer_);
+        SDL_RenderTexture(renderer_, back_buffer_, nullptr, nullptr);
+        SDL_RenderPresent(renderer_);
+        return;
+    }
+
+    // TODO: Implementar render loop de Metal
+    // 1. Obtener drawable del layer
+    // 2. Crear command buffer
+    // 3. Crear render pass descriptor
+    // 4. Encodear comandos de dibujo
+    // 5. Commit y presentar
+
+    // NOTA: Esta es la parte más compleja y requiere más trabajo
+    // Por ahora dejamos un stub para que compile
+
+    SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+               "Metal render() no implementado completamente todavía");
+}
+
+void MetalShader::setTextureSize(float width, float height) {
+    if (!is_initialized_) {
+        return;
+    }
+
+    texture_width_ = width;
+    texture_height_ = height;
+
+    // Actualizar uniforms
+    uniforms_.textureSize[0] = width;
+    uniforms_.textureSize[1] = height;
+
+    memcpy([uniforms_buffer_ contents], &uniforms_, sizeof(Uniforms));
+}
+
+void MetalShader::cleanup() {
+    // En Objective-C++ con ARC, no necesitamos release manual
+    // pero limpiamos las referencias
+    pipeline_state_ = nil;
+    command_queue_ = nil;
+    vertex_buffer_ = nil;
+    index_buffer_ = nil;
+    uniforms_buffer_ = nil;
+    device_ = nil;
+    metal_layer_ = nil;
+
+    is_initialized_ = false;
+}
+
+id<MTLTexture> MetalShader::getMetalTexture(SDL_Texture* texture) {
+    // TODO: Obtener la textura Metal desde SDL_Texture
+    // Esto requiere acceder a las properties de SDL3
+    return nil;
+}
+
+} // namespace Rendering
+
+#endif // __APPLE__

source/rendering/opengl/opengl_shader.cpp

@@ -0,0 +1,455 @@
+#include "opengl_shader.h"
+
+#include <SDL3/SDL.h>
+#include <cstring>
+#include <stdexcept>
+#include <vector>
+
+namespace Rendering {
+
+OpenGLShader::~OpenGLShader() {
+    cleanup();
+}
+
+#ifndef __APPLE__
+bool OpenGLShader::initGLExtensions() {
+    glCreateShader = (PFNGLCREATESHADERPROC)SDL_GL_GetProcAddress("glCreateShader");
+    glShaderSource = (PFNGLSHADERSOURCEPROC)SDL_GL_GetProcAddress("glShaderSource");
+    glCompileShader = (PFNGLCOMPILESHADERPROC)SDL_GL_GetProcAddress("glCompileShader");
+    glGetShaderiv = (PFNGLGETSHADERIVPROC)SDL_GL_GetProcAddress("glGetShaderiv");
+    glGetShaderInfoLog = (PFNGLGETSHADERINFOLOGPROC)SDL_GL_GetProcAddress("glGetShaderInfoLog");
+    glDeleteShader = (PFNGLDELETESHADERPROC)SDL_GL_GetProcAddress("glDeleteShader");
+    glAttachShader = (PFNGLATTACHSHADERPROC)SDL_GL_GetProcAddress("glAttachShader");
+    glCreateProgram = (PFNGLCREATEPROGRAMPROC)SDL_GL_GetProcAddress("glCreateProgram");
+    glLinkProgram = (PFNGLLINKPROGRAMPROC)SDL_GL_GetProcAddress("glLinkProgram");
+    glValidateProgram = (PFNGLVALIDATEPROGRAMPROC)SDL_GL_GetProcAddress("glValidateProgram");
+    glGetProgramiv = (PFNGLGETPROGRAMIVPROC)SDL_GL_GetProcAddress("glGetProgramiv");
+    glGetProgramInfoLog = (PFNGLGETPROGRAMINFOLOGPROC)SDL_GL_GetProcAddress("glGetProgramInfoLog");
+    glUseProgram = (PFNGLUSEPROGRAMPROC)SDL_GL_GetProcAddress("glUseProgram");
+    glDeleteProgram = (PFNGLDELETEPROGRAMPROC)SDL_GL_GetProcAddress("glDeleteProgram");
+    glGetUniformLocation = (PFNGLGETUNIFORMLOCATIONPROC)SDL_GL_GetProcAddress("glGetUniformLocation");
+    glUniform2f = (PFNGLUNIFORM2FPROC)SDL_GL_GetProcAddress("glUniform2f");
+    glGenVertexArrays = (PFNGLGENVERTEXARRAYSPROC)SDL_GL_GetProcAddress("glGenVertexArrays");
+    glBindVertexArray = (PFNGLBINDVERTEXARRAYPROC)SDL_GL_GetProcAddress("glBindVertexArray");
+    glDeleteVertexArrays = (PFNGLDELETEVERTEXARRAYSPROC)SDL_GL_GetProcAddress("glDeleteVertexArrays");
+    glGenBuffers = (PFNGLGENBUFFERSPROC)SDL_GL_GetProcAddress("glGenBuffers");
+    glBindBuffer = (PFNGLBINDBUFFERPROC)SDL_GL_GetProcAddress("glBindBuffer");
+    glBufferData = (PFNGLBUFFERDATAPROC)SDL_GL_GetProcAddress("glBufferData");
+    glDeleteBuffers = (PFNGLDELETEBUFFERSPROC)SDL_GL_GetProcAddress("glDeleteBuffers");
+    glVertexAttribPointer = (PFNGLVERTEXATTRIBPOINTERPROC)SDL_GL_GetProcAddress("glVertexAttribPointer");
+    glEnableVertexAttribArray = (PFNGLENABLEVERTEXATTRIBARRAYPROC)SDL_GL_GetProcAddress("glEnableVertexAttribArray");
+
+    return glCreateShader && glShaderSource && glCompileShader && glGetShaderiv &&
+           glGetShaderInfoLog && glDeleteShader && glAttachShader && glCreateProgram &&
+           glLinkProgram && glValidateProgram && glGetProgramiv && glGetProgramInfoLog &&
+           glUseProgram && glDeleteProgram && glGetUniformLocation && glUniform2f &&
+           glGenVertexArrays && glBindVertexArray && glDeleteVertexArrays &&
+           glGenBuffers && glBindBuffer && glBufferData && glDeleteBuffers &&
+           glVertexAttribPointer && glEnableVertexAttribArray;
+}
+#endif
+
+void OpenGLShader::checkGLError(const char* operation) {
+    GLenum error = glGetError();
+    if (error != GL_NO_ERROR) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error OpenGL en %s: 0x%x", operation, error);
+    }
+}
+
+GLuint OpenGLShader::compileShader(const std::string& source, GLenum shader_type) {
+    if (source.empty()) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "ERROR: El código fuente del shader está vacío");
+        return 0;
+    }
+
+    GLuint shader_id = glCreateShader(shader_type);
+    if (shader_id == 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error al crear shader");
+        checkGLError("glCreateShader");
+        return 0;
+    }
+
+    const char* sources[1] = {source.c_str()};
+    glShaderSource(shader_id, 1, sources, nullptr);
+    checkGLError("glShaderSource");
+
+    glCompileShader(shader_id);
+    checkGLError("glCompileShader");
+
+    // Verificar compilación
+    GLint compiled = GL_FALSE;
+    glGetShaderiv(shader_id, GL_COMPILE_STATUS, &compiled);
+    if (compiled != GL_TRUE) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error en compilación del shader");
+        GLint log_length;
+        glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &log_length);
+        if (log_length > 0) {
+            std::vector<char> log(log_length);
+            glGetShaderInfoLog(shader_id, log_length, &log_length, log.data());
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                        "Log de compilación: %s", log.data());
+        }
+        glDeleteShader(shader_id);
+        return 0;
+    }
+
+    return shader_id;
+}
+
+GLuint OpenGLShader::linkProgram(GLuint vertex_shader, GLuint fragment_shader) {
+    GLuint program = glCreateProgram();
+    if (program == 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error al crear programa de shaders");
+        return 0;
+    }
+
+    glAttachShader(program, vertex_shader);
+    checkGLError("glAttachShader(vertex)");
+    glAttachShader(program, fragment_shader);
+    checkGLError("glAttachShader(fragment)");
+
+    glLinkProgram(program);
+    checkGLError("glLinkProgram");
+
+    // Verificar enlace
+    GLint linked = GL_FALSE;
+    glGetProgramiv(program, GL_LINK_STATUS, &linked);
+    if (linked != GL_TRUE) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error al enlazar programa");
+        GLint log_length;
+        glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
+        if (log_length > 0) {
+            std::vector<char> log(log_length);
+            glGetProgramInfoLog(program, log_length, &log_length, log.data());
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                        "Log de enlace: %s", log.data());
+        }
+        glDeleteProgram(program);
+        return 0;
+    }
+
+    glValidateProgram(program);
+    checkGLError("glValidateProgram");
+
+    return program;
+}
+
+void OpenGLShader::createQuadGeometry() {
+    // Datos del quad: posición (x, y) + coordenadas de textura (u, v)
+    // Formato: x, y, u, v
+    float vertices[] = {
+        // Posición      // TexCoords
+        -1.0f, -1.0f,    0.0f, 0.0f,  // Inferior izquierda
+         1.0f, -1.0f,    1.0f, 0.0f,  // Inferior derecha
+         1.0f,  1.0f,    1.0f, 1.0f,  // Superior derecha
+        -1.0f,  1.0f,    0.0f, 1.0f   // Superior izquierda
+    };
+
+    // Índices para dibujar el quad con dos triángulos
+    unsigned int indices[] = {
+        0, 1, 2,  // Primer triángulo
+        2, 3, 0   // Segundo triángulo
+    };
+
+    // Generar y configurar VAO
+    glGenVertexArrays(1, &vao_);
+    glBindVertexArray(vao_);
+    checkGLError("glBindVertexArray");
+
+    // Generar y configurar VBO
+    glGenBuffers(1, &vbo_);
+    glBindBuffer(GL_ARRAY_BUFFER, vbo_);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+    checkGLError("glBufferData(VBO)");
+
+    // Generar y configurar EBO
+    glGenBuffers(1, &ebo_);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo_);
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
+    checkGLError("glBufferData(EBO)");
+
+    // Atributo 0: Posición (2 floats)
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);
+    glEnableVertexAttribArray(0);
+    checkGLError("glVertexAttribPointer(position)");
+
+    // Atributo 1: Coordenadas de textura (2 floats)
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)(2 * sizeof(float)));
+    glEnableVertexAttribArray(1);
+    checkGLError("glVertexAttribPointer(texcoord)");
+
+    // Desvincular
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glBindVertexArray(0);
+}
+
+GLuint OpenGLShader::getTextureID(SDL_Texture* texture) {
+    if (!texture) return 1;
+
+    SDL_PropertiesID props = SDL_GetTextureProperties(texture);
+    GLuint texture_id = 0;
+
+    // Intentar obtener ID de textura OpenGL
+    texture_id = (GLuint)(uintptr_t)SDL_GetPointerProperty(props, "SDL.texture.opengl.texture", nullptr);
+
+    if (texture_id == 0) {
+        texture_id = (GLuint)(uintptr_t)SDL_GetPointerProperty(props, "texture.opengl.texture", nullptr);
+    }
+
+    if (texture_id == 0) {
+        texture_id = (GLuint)SDL_GetNumberProperty(props, "SDL.texture.opengl.texture", 1);
+    }
+
+    if (texture_id == 0) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                   "No se pudo obtener ID de textura OpenGL, usando 1 por defecto");
+        texture_id = 1;
+    }
+
+    return texture_id;
+}
+
+bool OpenGLShader::init(SDL_Window* window,
+                        SDL_Texture* texture,
+                        const std::string& vertex_source,
+                        const std::string& fragment_source) {
+    window_ = window;
+    back_buffer_ = texture;
+    renderer_ = SDL_GetRenderer(window);
+
+    if (!renderer_) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error: No se pudo obtener el renderer");
+        return false;
+    }
+
+    // Obtener tamaños
+    SDL_GetWindowSize(window_, &window_width_, &window_height_);
+    SDL_GetTextureSize(back_buffer_, &texture_width_, &texture_height_);
+
+    // Verificar que es OpenGL
+    const char* renderer_name = SDL_GetRendererName(renderer_);
+    if (!renderer_name || strncmp(renderer_name, "opengl", 6) != 0) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                   "Renderer no es OpenGL: %s", renderer_name ? renderer_name : "unknown");
+        return false;
+    }
+
+#ifndef __APPLE__
+    // Inicializar extensiones OpenGL en Windows/Linux
+    if (!initGLExtensions()) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error al inicializar extensiones OpenGL");
+        return false;
+    }
+#endif
+
+    // Limpiar shader anterior si existe
+    if (program_id_ != 0) {
+        glDeleteProgram(program_id_);
+        program_id_ = 0;
+    }
+
+    // Compilar shaders
+    GLuint vertex_shader = compileShader(vertex_source, GL_VERTEX_SHADER);
+    GLuint fragment_shader = compileShader(fragment_source, GL_FRAGMENT_SHADER);
+
+    if (vertex_shader == 0 || fragment_shader == 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error al compilar shaders");
+        if (vertex_shader != 0) glDeleteShader(vertex_shader);
+        if (fragment_shader != 0) glDeleteShader(fragment_shader);
+        return false;
+    }
+
+    // Enlazar programa
+    program_id_ = linkProgram(vertex_shader, fragment_shader);
+
+    // Limpiar shaders (ya no necesarios tras el enlace)
+    glDeleteShader(vertex_shader);
+    glDeleteShader(fragment_shader);
+
+    if (program_id_ == 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
+                    "Error al crear programa de shaders");
+        return false;
+    }
+
+    // Crear geometría del quad
+    createQuadGeometry();
+
+    // Obtener ubicación del uniform TextureSize
+    glUseProgram(program_id_);
+    texture_size_location_ = glGetUniformLocation(program_id_, "TextureSize");
+    if (texture_size_location_ != -1) {
+        glUniform2f(texture_size_location_, texture_width_, texture_height_);
+        checkGLError("glUniform2f(TextureSize)");
+    } else {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+                   "Uniform 'TextureSize' no encontrado en shader");
+    }
+    glUseProgram(0);
+
+    is_initialized_ = true;
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+               "** OpenGL 3.3 Shader Backend inicializado correctamente");
+
+    return true;
+}
+
+void OpenGLShader::render() {
+    if (!is_initialized_ || program_id_ == 0) {
+        // Fallback: renderizado SDL normal
+        SDL_SetRenderDrawColor(renderer_, 0, 0, 0, 255);
+        SDL_SetRenderTarget(renderer_, nullptr);
+        SDL_RenderClear(renderer_);
+        SDL_RenderTexture(renderer_, back_buffer_, nullptr, nullptr);
+        SDL_RenderPresent(renderer_);
+        return;
+    }
+
+    // Obtener tamaño actual de ventana (puede haber cambiado)
+    int current_width, current_height;
+    SDL_GetWindowSize(window_, &current_width, &current_height);
+
+    // Guardar estados OpenGL
+    GLint old_program;
+    glGetIntegerv(GL_CURRENT_PROGRAM, &old_program);
+
+    GLint old_viewport[4];
+    glGetIntegerv(GL_VIEWPORT, old_viewport);
+
+    GLboolean was_texture_enabled = glIsEnabled(GL_TEXTURE_2D);
+    GLint old_texture;
+    glGetIntegerv(GL_TEXTURE_BINDING_2D, &old_texture);
+
+    GLint old_vao;
+    glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &old_vao);
+
+    // Preparar renderizado
+    SDL_SetRenderDrawColor(renderer_, 0, 0, 0, 255);
+    SDL_SetRenderTarget(renderer_, nullptr);
+    SDL_RenderClear(renderer_);
+
+    // Obtener y bindear textura
+    GLuint texture_id = getTextureID(back_buffer_);
+    glEnable(GL_TEXTURE_2D);
+    glBindTexture(GL_TEXTURE_2D, texture_id);
+    checkGLError("glBindTexture");
+
+    // Usar nuestro programa
+    glUseProgram(program_id_);
+    checkGLError("glUseProgram");
+
+    // Configurar viewport (obtener tamaño lógico de SDL)
+    int logical_w, logical_h;
+    SDL_RendererLogicalPresentation mode;
+    SDL_GetRenderLogicalPresentation(renderer_, &logical_w, &logical_h, &mode);
+
+    if (logical_w == 0 || logical_h == 0) {
+        logical_w = current_width;
+        logical_h = current_height;
+    }
+
+    // Calcular viewport considerando aspect ratio
+    int viewport_x = 0, viewport_y = 0;
+    int viewport_w = current_width, viewport_h = current_height;
+
+    if (mode == SDL_LOGICAL_PRESENTATION_INTEGER_SCALE) {
+        int scale_x = current_width / logical_w;
+        int scale_y = current_height / logical_h;
+        int scale = (scale_x < scale_y) ? scale_x : scale_y;
+        if (scale < 1) scale = 1;
+
+        viewport_w = logical_w * scale;
+        viewport_h = logical_h * scale;
+        viewport_x = (current_width - viewport_w) / 2;
+        viewport_y = (current_height - viewport_h) / 2;
+    } else {
+        float window_aspect = static_cast<float>(current_width) / current_height;
+        float logical_aspect = static_cast<float>(logical_w) / logical_h;
+
+        if (window_aspect > logical_aspect) {
+            viewport_w = static_cast<int>(logical_aspect * current_height);
+            viewport_x = (current_width - viewport_w) / 2;
+        } else {
+            viewport_h = static_cast<int>(current_width / logical_aspect);
+            viewport_y = (current_height - viewport_h) / 2;
+        }
+    }
+
+    glViewport(viewport_x, viewport_y, viewport_w, viewport_h);
+    checkGLError("glViewport");
+
+    // Dibujar quad usando VAO
+    glBindVertexArray(vao_);
+    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
+    checkGLError("glDrawElements");
+
+    // Presentar
+    SDL_GL_SwapWindow(window_);
+
+    // Restaurar estados OpenGL
+    glUseProgram(old_program);
+    glBindTexture(GL_TEXTURE_2D, old_texture);
+    if (!was_texture_enabled) {
+        glDisable(GL_TEXTURE_2D);
+    }
+    glBindVertexArray(old_vao);
+    glViewport(old_viewport[0], old_viewport[1], old_viewport[2], old_viewport[3]);
+}
+
+void OpenGLShader::setTextureSize(float width, float height) {
+    if (!is_initialized_ || program_id_ == 0) {
+        return;
+    }
+
+    texture_width_ = width;
+    texture_height_ = height;
+
+    GLint old_program;
+    glGetIntegerv(GL_CURRENT_PROGRAM, &old_program);
+
+    glUseProgram(program_id_);
+
+    if (texture_size_location_ != -1) {
+        glUniform2f(texture_size_location_, width, height);
+        checkGLError("glUniform2f(TextureSize)");
+    }
+
+    glUseProgram(old_program);
+}
+
+void OpenGLShader::cleanup() {
+    if (vao_ != 0) {
+        glDeleteVertexArrays(1, &vao_);
+        vao_ = 0;
+    }
+
+    if (vbo_ != 0) {
+        glDeleteBuffers(1, &vbo_);
+        vbo_ = 0;
+    }
+
+    if (ebo_ != 0) {
+        glDeleteBuffers(1, &ebo_);
+        ebo_ = 0;
+    }
+
+    if (program_id_ != 0) {
+        glDeleteProgram(program_id_);
+        program_id_ = 0;
+    }
+
+    is_initialized_ = false;
+    window_ = nullptr;
+    renderer_ = nullptr;
+    back_buffer_ = nullptr;
+}
+
+} // namespace Rendering

source/rendering/opengl/opengl_shader.h

@@ -0,0 +1,98 @@
+#pragma once
+
+#include "../shader_backend.h"
+
+#ifdef __APPLE__
+#include <OpenGL/gl3.h>
+#else
+#include <SDL3/SDL_opengl.h>
+#endif
+
+namespace Rendering {
+
+/**
+ * @brief Backend de shaders usando OpenGL 3.3 Core Profile
+ *
+ * Implementa el renderizado de shaders usando APIs modernas de OpenGL:
+ * - VAO (Vertex Array Objects)
+ * - VBO (Vertex Buffer Objects)
+ * - Shaders GLSL #version 330 core
+ */
+class OpenGLShader : public ShaderBackend {
+public:
+    OpenGLShader() = default;
+    ~OpenGLShader() override;
+
+    bool init(SDL_Window* window,
+             SDL_Texture* texture,
+             const std::string& vertex_source,
+             const std::string& fragment_source) override;
+
+    void render() override;
+    void setTextureSize(float width, float height) override;
+    void cleanup() override;
+    bool isHardwareAccelerated() const override { return is_initialized_; }
+
+private:
+    // Funciones auxiliares
+    bool initGLExtensions();
+    GLuint compileShader(const std::string& source, GLenum shader_type);
+    GLuint linkProgram(GLuint vertex_shader, GLuint fragment_shader);
+    void createQuadGeometry();
+    GLuint getTextureID(SDL_Texture* texture);
+    void checkGLError(const char* operation);
+
+    // Estado SDL
+    SDL_Window* window_ = nullptr;
+    SDL_Renderer* renderer_ = nullptr;
+    SDL_Texture* back_buffer_ = nullptr;
+
+    // Estado OpenGL
+    GLuint program_id_ = 0;
+    GLuint vao_ = 0;  // Vertex Array Object
+    GLuint vbo_ = 0;  // Vertex Buffer Object
+    GLuint ebo_ = 0;  // Element Buffer Object
+
+    // Ubicaciones de uniforms
+    GLint texture_size_location_ = -1;
+
+    // Tamaños
+    int window_width_ = 0;
+    int window_height_ = 0;
+    float texture_width_ = 0.0f;
+    float texture_height_ = 0.0f;
+
+    // Estado
+    bool is_initialized_ = false;
+
+#ifndef __APPLE__
+    // Punteros a funciones OpenGL en Windows/Linux
+    PFNGLCREATESHADERPROC glCreateShader = nullptr;
+    PFNGLSHADERSOURCEPROC glShaderSource = nullptr;
+    PFNGLCOMPILESHADERPROC glCompileShader = nullptr;
+    PFNGLGETSHADERIVPROC glGetShaderiv = nullptr;
+    PFNGLGETSHADERINFOLOGPROC glGetShaderInfoLog = nullptr;
+    PFNGLDELETESHADERPROC glDeleteShader = nullptr;
+    PFNGLATTACHSHADERPROC glAttachShader = nullptr;
+    PFNGLCREATEPROGRAMPROC glCreateProgram = nullptr;
+    PFNGLLINKPROGRAMPROC glLinkProgram = nullptr;
+    PFNGLVALIDATEPROGRAMPROC glValidateProgram = nullptr;
+    PFNGLGETPROGRAMIVPROC glGetProgramiv = nullptr;
+    PFNGLGETPROGRAMINFOLOGPROC glGetProgramInfoLog = nullptr;
+    PFNGLUSEPROGRAMPROC glUseProgram = nullptr;
+    PFNGLDELETEPROGRAMPROC glDeleteProgram = nullptr;
+    PFNGLGETUNIFORMLOCATIONPROC glGetUniformLocation = nullptr;
+    PFNGLUNIFORM2FPROC glUniform2f = nullptr;
+    PFNGLGENVERTEXARRAYSPROC glGenVertexArrays = nullptr;
+    PFNGLBINDVERTEXARRAYPROC glBindVertexArray = nullptr;
+    PFNGLDELETEVERTEXARRAYSPROC glDeleteVertexArrays = nullptr;
+    PFNGLGENBUFFERSPROC glGenBuffers = nullptr;
+    PFNGLBINDBUFFERPROC glBindBuffer = nullptr;
+    PFNGLBUFFERDATAPROC glBufferData = nullptr;
+    PFNGLDELETEBUFFERSPROC glDeleteBuffers = nullptr;
+    PFNGLVERTEXATTRIBPOINTERPROC glVertexAttribPointer = nullptr;
+    PFNGLENABLEVERTEXATTRIBARRAYPROC glEnableVertexAttribArray = nullptr;
+#endif
+};
+
+} // namespace Rendering

source/rendering/shader_backend.h

@@ -0,0 +1,55 @@
+#pragma once
+
+#include <SDL3/SDL.h>
+#include <string>
+
+namespace Rendering {
+
+/**
+ * @brief Interfaz abstracta para backends de renderizado con shaders
+ *
+ * Esta interfaz define el contrato que todos los backends de shaders
+ * deben cumplir (OpenGL, Metal, Vulkan, etc.)
+ */
+class ShaderBackend {
+public:
+    virtual ~ShaderBackend() = default;
+
+    /**
+     * @brief Inicializa el backend de shaders
+     * @param window Ventana SDL
+     * @param texture Textura de backbuffer a la que aplicar shaders
+     * @param vertex_source Código fuente del vertex shader
+     * @param fragment_source Código fuente del fragment shader
+     * @return true si la inicialización fue exitosa
+     */
+    virtual bool init(SDL_Window* window,
+                     SDL_Texture* texture,
+                     const std::string& vertex_source,
+                     const std::string& fragment_source) = 0;
+
+    /**
+     * @brief Renderiza la textura con los shaders aplicados
+     */
+    virtual void render() = 0;
+
+    /**
+     * @brief Establece el tamaño de la textura como parámetro del shader
+     * @param width Ancho de la textura
+     * @param height Alto de la textura
+     */
+    virtual void setTextureSize(float width, float height) = 0;
+
+    /**
+     * @brief Limpia y libera recursos del backend
+     */
+    virtual void cleanup() = 0;
+
+    /**
+     * @brief Verifica si el backend está usando aceleración por hardware
+     * @return true si usa aceleración (OpenGL/Metal/Vulkan)
+     */
+    virtual bool isHardwareAccelerated() const = 0;
+};
+
+} // namespace Rendering

source/screen.cpp

@@ -8,9 +8,12 @@
 #include <memory>     // Para allocator, shared_ptr, make_shared, __shared_ptr_access
 #include <string>     // Para operator+, char_traits, to_string, string
 
-#include "asset.h"                 // Para Asset
+#include "asset.h"                              // Para Asset
-#include "external/jail_shader.h"  // Para init, render
+#include "mouse.h"                              // Para updateCursorVisibility
-#include "mouse.h"                 // Para updateCursorVisibility
+#include "rendering/opengl/opengl_shader.h"     // Para OpenGLShader
+#ifdef __APPLE__
+// #include "rendering/metal/metal_shader.h"    // Para MetalShader (TODO: descomentar cuando esté completo)
+#endif
 #include "options.h"               // Para VideoOptions, video, WindowOptions, window
 #include "param.h"                 // Para Param, param, ParamGame, ParamDebug
 #include "text.h"                  // Para Text, Text::COLOR, Text::STROKE
@@ -55,9 +58,12 @@ Screen::Screen()
     setDebugInfoEnabled(true);
 #endif
 
-    // Inicializa los shaders
+    // Inicializa los shaders (solo en plataformas no-macOS por ahora)
+#ifndef __APPLE__
     loadShaders();
-    shader::init(window_, game_canvas_, shader_source_);
+    shader_backend_ = std::make_unique<Rendering::OpenGLShader>();
+    shader_backend_->init(window_, game_canvas_, vertex_shader_source_, fragment_shader_source_);
+#endif
 }
 
 // Destructor
@@ -97,8 +103,8 @@ void Screen::renderPresent() {
     SDL_SetRenderTarget(renderer_, nullptr);
     clean();
 
-    if (Options::video.shaders) {
+    if (Options::video.shaders && shader_backend_) {
-        shader::render();
+        shader_backend_->render();
     } else {
         SDL_RenderTexture(renderer_, game_canvas_, nullptr, nullptr);
         SDL_RenderPresent(renderer_);
@@ -223,23 +229,40 @@ void Screen::renderInfo() {
     }
 }
 #endif
-// Carga el contenido del archivo GLSL
+// Carga el contenido de los archivos GLSL
 void Screen::loadShaders() {
-    if (shader_source_.empty()) {
+    if (vertex_shader_source_.empty()) {
-        const std::string GLSL_FILE = "crtpi.glsl";
+        const std::string VERTEX_FILE = "crtpi_vertex.glsl";
-        auto data = Asset::get()->loadData(GLSL_FILE);
+        auto data = Asset::get()->loadData(VERTEX_FILE);
         if (!data.empty()) {
-            shader_source_ = std::string(data.begin(), data.end());
+            vertex_shader_source_ = std::string(data.begin(), data.end());
+        }
+    }
+    if (fragment_shader_source_.empty()) {
+        const std::string FRAGMENT_FILE = "crtpi_fragment.glsl";
+        auto data = Asset::get()->loadData(FRAGMENT_FILE);
+        if (!data.empty()) {
+            fragment_shader_source_ = std::string(data.begin(), data.end());
         }
     }
 }
 
 // Inicializa los shaders
 void Screen::initShaders() {
+#ifndef __APPLE__
     if (Options::video.shaders) {
         loadShaders();
-        shader::init(window_, game_canvas_, shader_source_);
+        if (!shader_backend_) {
+            shader_backend_ = std::make_unique<Rendering::OpenGLShader>();
+        }
+        shader_backend_->init(window_, game_canvas_, vertex_shader_source_, fragment_shader_source_);
     }
+#else
+    // En macOS, OpenGL está deprecated y rinde mal
+    // TODO: Implementar backend de Metal para shaders en macOS
+    SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+               "Shaders no disponibles en macOS (OpenGL deprecated). Usa Metal backend.");
+#endif
 }
 
 // Calcula el tamaño de la ventana
@@ -310,6 +333,10 @@ auto Screen::initSDLVideo() -> bool {
         SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
             "Warning: Failed to set OpenGL hint!");
     }
+    // Configurar contexto OpenGL 3.3 Core Profile
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
 #endif
 
     // Crear ventana

source/screen.h

@@ -8,10 +8,15 @@
 #include "color.h"    // Para Color
 #include "options.h"  // Para VideoOptions, video
 
+// Forward declarations
 class Notifier;
 class ServiceMenu;
 class Text;
 
+namespace Rendering {
+    class ShaderBackend;
+}
+
 // --- Clase Screen: gestiona la ventana, el renderizador y los efectos visuales globales (singleton) ---
 class Screen {
     public:
@@ -203,17 +208,19 @@ class Screen {
 #endif
 
         // --- Objetos y punteros ---
-        SDL_Window *window_;          // Ventana de la aplicación
+        SDL_Window *window_;                             // Ventana de la aplicación
-        SDL_Renderer *renderer_;      // El renderizador de la ventana
+        SDL_Renderer *renderer_;                         // El renderizador de la ventana
-        SDL_Texture *game_canvas_;    // Textura donde se dibuja todo antes de volcarse al renderizador
+        SDL_Texture *game_canvas_;                       // Textura donde se dibuja todo antes de volcarse al renderizador
-        ServiceMenu *service_menu_;   // Objeto para mostrar el menú de servicio
+        ServiceMenu *service_menu_;                      // Objeto para mostrar el menú de servicio
-        Notifier *notifier_;          // Objeto para mostrar las notificaciones por pantalla
+        Notifier *notifier_;                             // Objeto para mostrar las notificaciones por pantalla
-        std::shared_ptr<Text> text_;  // Objeto para escribir texto en pantalla
+        std::shared_ptr<Text> text_;                     // Objeto para escribir texto en pantalla
+        std::unique_ptr<Rendering::ShaderBackend> shader_backend_;  // Backend de shaders (OpenGL/Metal/Vulkan)
 
         // --- Variables de estado ---
         SDL_FRect src_rect_;             // Coordenadas de origen para dibujar la textura del juego
         SDL_FRect dst_rect_;             // Coordenadas destino para dibujar la textura del juego
-        std::string shader_source_;      // Almacena el contenido del archivo GLSL
+        std::string vertex_shader_source_;    // Almacena el vertex shader
+        std::string fragment_shader_source_;  // Almacena el fragment shader
         FPS fps_;                        // Gestión de frames por segundo
         FlashEffect flash_effect_;       // Efecto de flash en pantalla
         ShakeEffect shake_effect_;       // Efecto de agitar la pantalla