Metal post-processing pipeline implementation

- Add custom Metal render target creation
- Implement post-processing without GPU-CPU-GPU copies
- Create Metal texture extraction system
- Add Metal CRT shader pipeline integration
- Modify screen rendering to use Metal when available
- Enable shaders by default for testing

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

source/defaults.h

@@ -219,7 +219,7 @@ constexpr SDL_ScaleMode VIDEO_SCALE_MODE = SDL_ScaleMode::SDL_SCALEMODE_NEAREST;
 constexpr bool VIDEO_FULLSCREEN = false;
 constexpr bool VIDEO_VSYNC = true;
 constexpr bool VIDEO_INTEGER_SCALE = true;
-constexpr bool VIDEO_SHADERS = false;
+constexpr bool VIDEO_SHADERS = true;
 
 // Music
 constexpr bool MUSIC_ENABLED = true;

source/external/jail_shader.h

@@ -4,6 +4,20 @@
 #include <string>  // Para basic_string, string
 
 namespace shader {
-bool init(SDL_Window *ventana, SDL_Texture *texturaBackBuffer, const std::string &vertexShader, const std::string &fragmentShader = "");
+bool init(SDL_Window *ventana, SDL_Texture *texturaBackBuffer, const std::string &shaderSource, const std::string &fragmentShader = "");
 void render();
+void cleanup();
+bool isUsingOpenGL();
+
+#ifdef __APPLE__
+namespace metal {
+bool initMetal(SDL_Window* window, SDL_Texture* backBuffer, const std::string& shaderFilename);
+SDL_Texture* createMetalRenderTarget(SDL_Renderer* renderer, int width, int height);
+void updateMetalTexture(SDL_Texture* backBuffer);
+void renderMetal();
+void renderWithPostProcessing(SDL_Renderer* renderer, SDL_Texture* sourceTexture);
+void cleanupMetal();
+}
+#endif
+
 }  // namespace shader

source/external/jail_shader_metal.mm

@@ -0,0 +1,387 @@
+#include "jail_shader.h"
+
+#ifdef __APPLE__
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_metal.h>
+#include <Metal/Metal.h>
+#include <QuartzCore/CAMetalLayer.h>
+#include <CoreFoundation/CoreFoundation.h>
+#include <stdexcept>
+#include <vector>
+#include "../asset.h"
+
+namespace shader {
+namespace metal {
+
+// Metal objects
+id<MTLDevice> device = nullptr;
+id<MTLRenderPipelineState> pipelineState = nullptr;
+id<MTLBuffer> vertexBuffer = nullptr;
+id<MTLTexture> backBufferTexture = nullptr;
+id<MTLTexture> gameCanvasTexture = nullptr;  // Our custom render target texture
+id<MTLSamplerState> sampler = nullptr;
+
+// SDL objects (references from main shader module)
+SDL_Window* win = nullptr;
+SDL_Renderer* renderer = nullptr;
+SDL_Texture* backBuffer = nullptr;
+
+// Vertex data for fullscreen quad
+struct Vertex {
+    float position[4];  // x, y, z, w
+    float texcoord[2];  // u, v
+};
+
+const Vertex quadVertices[] = {
+    // Position (x, y, z, w)     // TexCoord (u, v) - Standard OpenGL-style coordinates
+    {{-1.0f, -1.0f, 0.0f, 1.0f}, {0.0f, 1.0f}}, // Bottom-left
+    {{ 1.0f, -1.0f, 0.0f, 1.0f}, {1.0f, 1.0f}}, // Bottom-right
+    {{-1.0f,  1.0f, 0.0f, 1.0f}, {0.0f, 0.0f}}, // Top-left
+    {{ 1.0f,  1.0f, 0.0f, 1.0f}, {1.0f, 0.0f}}, // Top-right
+};
+
+std::string loadMetalShader(const std::string& filename) {
+    // Try to load the .metal file from the same location as GLSL files
+    auto data = Asset::get()->loadData(filename);
+    if (!data.empty()) {
+        return std::string(data.begin(), data.end());
+    }
+    return "";
+}
+
+SDL_Texture* createMetalRenderTarget(SDL_Renderer* renderer, int width, int height) {
+    if (!renderer) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "createMetalRenderTarget: No renderer provided");
+        return nullptr;
+    }
+
+    // Crear textura Metal como render target
+    SDL_Texture* metalTexture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, width, height);
+    if (!metalTexture) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create Metal render target texture: %s", SDL_GetError());
+        return nullptr;
+    }
+
+    // Configurar filtrado nearest neighbor para look pixelado
+    SDL_SetTextureScaleMode(metalTexture, SDL_SCALEMODE_NEAREST);
+
+    // Try to extract and store the Metal texture directly
+    SDL_PropertiesID props = SDL_GetTextureProperties(metalTexture);
+    if (props != 0) {
+        const char* propertyNames[] = {
+            "SDL.texture.metal.texture",
+            "SDL.renderer.metal.texture",
+            "metal.texture",
+            "texture.metal",
+            "MTLTexture",
+            "texture"
+        };
+
+        for (const char* propName : propertyNames) {
+            gameCanvasTexture = (__bridge id<MTLTexture>)SDL_GetPointerProperty(props, propName, nullptr);
+            if (gameCanvasTexture) {
+                SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Successfully extracted Metal texture via property '%s' (size: %lux%lu)",
+                           propName, [gameCanvasTexture width], [gameCanvasTexture height]);
+                break;
+            }
+        }
+    }
+
+    if (!gameCanvasTexture) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "Could not extract Metal texture from SDL texture - shaders may not work");
+    }
+
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Created Metal render target texture (%dx%d)", width, height);
+    return metalTexture;
+}
+
+bool initMetal(SDL_Window* window, SDL_Texture* backBufferTexture, const std::string& shaderFilename) {
+    // Store references
+    win = window;
+    backBuffer = backBufferTexture;
+    renderer = SDL_GetRenderer(window);
+    
+    if (!renderer) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to get SDL renderer");
+        return false;
+    }
+    
+    // Get Metal layer from SDL renderer and extract device from it
+    CAMetalLayer* metalLayer = (__bridge CAMetalLayer*)SDL_GetRenderMetalLayer(renderer);
+    if (!metalLayer) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to get Metal layer from SDL renderer");
+        return false;
+    }
+    
+    device = metalLayer.device;
+    if (!device) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to get Metal device from layer");
+        return false;
+    }
+    
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Got Metal device from SDL layer: %s", [[device name] UTF8String]);
+    
+    // Note: We no longer need our own texture - we'll use the backBuffer directly
+    
+    // Load and compile shaders
+    std::string metalShaderSource = loadMetalShader(shaderFilename);
+    if (metalShaderSource.empty()) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to load Metal shader: %s", shaderFilename.c_str());
+        return false;
+    }
+    
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Loaded Metal shader %s (length: %zu)", 
+                shaderFilename.c_str(), metalShaderSource.length());
+    
+    NSString* shaderNSString = [NSString stringWithUTF8String:metalShaderSource.c_str()];
+    NSError* error = nil;
+    id<MTLLibrary> library = [device newLibraryWithSource:shaderNSString options:nil error:&error];
+    if (!library || error) {
+        if (error) {
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to compile Metal shader: %s", 
+                        [[error localizedDescription] UTF8String]);
+        }
+        return false;
+    }
+    
+    id<MTLFunction> vertexFunction = [library newFunctionWithName:@"vertex_main"];
+    id<MTLFunction> fragmentFunction = [library newFunctionWithName:@"fragment_main"];
+    
+    if (!vertexFunction || !fragmentFunction) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to load Metal shader functions");
+        return false;
+    }
+    
+    // Create render pipeline
+    MTLRenderPipelineDescriptor* pipelineDescriptor = [[MTLRenderPipelineDescriptor alloc] init];
+    pipelineDescriptor.vertexFunction = vertexFunction;
+    pipelineDescriptor.fragmentFunction = fragmentFunction;
+    pipelineDescriptor.colorAttachments[0].pixelFormat = MTLPixelFormatBGRA8Unorm;
+    
+    // Set up vertex descriptor
+    MTLVertexDescriptor* vertexDescriptor = [[MTLVertexDescriptor alloc] init];
+    vertexDescriptor.attributes[0].format = MTLVertexFormatFloat4;
+    vertexDescriptor.attributes[0].offset = 0;
+    vertexDescriptor.attributes[0].bufferIndex = 0;
+    vertexDescriptor.attributes[1].format = MTLVertexFormatFloat2;
+    vertexDescriptor.attributes[1].offset = 4 * sizeof(float);
+    vertexDescriptor.attributes[1].bufferIndex = 0;
+    vertexDescriptor.layouts[0].stride = sizeof(Vertex);
+    vertexDescriptor.layouts[0].stepFunction = MTLVertexStepFunctionPerVertex;
+    
+    pipelineDescriptor.vertexDescriptor = vertexDescriptor;
+    
+    pipelineState = [device newRenderPipelineStateWithDescriptor:pipelineDescriptor error:&error];
+    if (!pipelineState || error) {
+        if (error) {
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create Metal render pipeline: %s", 
+                        [[error localizedDescription] UTF8String]);
+        }
+        return false;
+    }
+    
+    // Create vertex buffer
+    vertexBuffer = [device newBufferWithBytes:quadVertices 
+                                       length:sizeof(quadVertices) 
+                                      options:MTLResourceOptionCPUCacheModeDefault];
+    
+    // Create sampler state for nearest neighbor filtering (pixelated look)
+    MTLSamplerDescriptor* samplerDescriptor = [[MTLSamplerDescriptor alloc] init];
+    samplerDescriptor.minFilter = MTLSamplerMinMagFilterNearest;
+    samplerDescriptor.magFilter = MTLSamplerMinMagFilterNearest;
+    samplerDescriptor.sAddressMode = MTLSamplerAddressModeClampToEdge;
+    samplerDescriptor.tAddressMode = MTLSamplerAddressModeClampToEdge;
+    
+    sampler = [device newSamplerStateWithDescriptor:samplerDescriptor];
+    
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "** Metal shader system initialized successfully");
+    return true;
+}
+
+void updateMetalTexture(SDL_Texture* backBuffer) {
+    if (!device || !backBuffer) return;
+    
+    // Only log this occasionally to avoid spam
+    static int attemptCount = 0;
+    static bool hasLogged = false;
+    
+    // Try multiple property names that SDL3 might use
+    SDL_PropertiesID props = SDL_GetTextureProperties(backBuffer);
+    if (props != 0) {
+        const char* propertyNames[] = {
+            "SDL.texture.metal.texture",
+            "SDL.renderer.metal.texture", 
+            "metal.texture",
+            "texture.metal",
+            "MTLTexture",
+            "texture"
+        };
+        
+        for (const char* propName : propertyNames) {
+            id<MTLTexture> sdlMetalTexture = (__bridge id<MTLTexture>)SDL_GetPointerProperty(props, propName, nullptr);
+            if (sdlMetalTexture) {
+                backBufferTexture = sdlMetalTexture;
+                if (!hasLogged) {
+                    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Got Metal texture via property '%s' (size: %lux%lu)", 
+                               propName, [backBufferTexture width], [backBufferTexture height]);
+                    hasLogged = true;
+                }
+                return;
+            }
+        }
+    }
+    
+    // If we can't get the texture after several attempts, log once and continue
+    if (!hasLogged && attemptCount++ > 10) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "Could not access SDL Metal texture after %d attempts - shader will be skipped", attemptCount);
+        hasLogged = true;
+    }
+}
+
+void renderMetal() {
+    if (!renderer || !device || !pipelineState) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Metal render failed: missing components");
+        return;
+    }
+
+    // Correct pipeline: backBuffer → Metal shaders → screen (no double rendering)
+
+    // Try to get the Metal texture directly from the SDL backBuffer texture
+    updateMetalTexture(backBuffer);
+
+    if (!backBufferTexture) {
+        static int fallbackLogCount = 0;
+        if (fallbackLogCount++ < 3) {
+            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "Metal texture not available - falling back to normal SDL rendering (attempt %d)", fallbackLogCount);
+        }
+        // Fallback: render without shaders using normal SDL path
+        SDL_SetRenderTarget(renderer, nullptr);
+        SDL_RenderTexture(renderer, backBuffer, nullptr, nullptr);
+        SDL_RenderPresent(renderer);
+        return;
+    }
+    
+    // Apply Metal CRT shader directly: backBuffer texture → screen
+    SDL_SetRenderTarget(renderer, nullptr);
+    
+    // Get Metal command encoder to render directly to screen
+    void* encoder_ptr = SDL_GetRenderMetalCommandEncoder(renderer);
+    if (encoder_ptr) {
+        id<MTLRenderCommandEncoder> encoder = (__bridge id<MTLRenderCommandEncoder>)encoder_ptr;
+
+        static int debugCount = 0;
+        if (debugCount++ < 5) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Metal render attempt %d: encoder=%p, pipeline=%p, texture=%p",
+                       debugCount, encoder, pipelineState, backBufferTexture);
+        }
+
+        // Apply CRT shader effect directly to backBuffer texture
+        [encoder setRenderPipelineState:pipelineState];
+        [encoder setVertexBuffer:vertexBuffer offset:0 atIndex:0];
+        [encoder setFragmentTexture:backBufferTexture atIndex:0];
+        [encoder setFragmentSamplerState:sampler atIndex:0];
+
+        // Draw fullscreen quad with CRT effect directly to screen
+        [encoder drawPrimitives:MTLPrimitiveTypeTriangleStrip vertexStart:0 vertexCount:4];
+
+        static int successCount = 0;
+        if (successCount++ < 5) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Applied CRT shader to backBuffer (attempt %d) - texture size: %lux%lu",
+                       successCount, [backBufferTexture width], [backBufferTexture height]);
+        }
+    } else {
+        // Fallback: render normally without shaders
+        SDL_RenderTexture(renderer, backBuffer, nullptr, nullptr);
+
+        static int fallbackCount = 0;
+        if (fallbackCount++ < 3) {
+            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "Failed to get Metal command encoder - fallback rendering");
+        }
+    }
+    
+    SDL_RenderPresent(renderer);
+}
+
+void renderWithPostProcessing(SDL_Renderer* renderer, SDL_Texture* sourceTexture) {
+    if (!renderer || !sourceTexture || !device || !pipelineState) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Metal post-processing failed: missing components");
+        // Fallback: render normally without shaders
+        SDL_SetRenderTarget(renderer, nullptr);
+        SDL_RenderTexture(renderer, sourceTexture, nullptr, nullptr);
+        SDL_RenderPresent(renderer);
+        return;
+    }
+
+    // Use our stored Metal texture if available
+    id<MTLTexture> metalTexture = gameCanvasTexture;
+
+    if (!metalTexture) {
+        static int fallbackLogCount = 0;
+        if (fallbackLogCount++ < 3) {
+            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "gameCanvasTexture not available - falling back to normal rendering (attempt %d)", fallbackLogCount);
+        }
+        // Fallback: render normally without shaders
+        SDL_SetRenderTarget(renderer, nullptr);
+        SDL_RenderTexture(renderer, sourceTexture, nullptr, nullptr);
+        SDL_RenderPresent(renderer);
+        return;
+    }
+
+    // Apply Metal CRT shader post-processing: sourceTexture → screen
+    SDL_SetRenderTarget(renderer, nullptr);
+
+    // Get Metal command encoder to render directly to screen
+    void* encoder_ptr = SDL_GetRenderMetalCommandEncoder(renderer);
+    if (encoder_ptr) {
+        id<MTLRenderCommandEncoder> encoder = (__bridge id<MTLRenderCommandEncoder>)encoder_ptr;
+
+        static int debugCount = 0;
+        if (debugCount++ < 3) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Metal post-processing attempt %d: encoder=%p, pipeline=%p, texture=%p",
+                       debugCount, encoder, pipelineState, metalTexture);
+        }
+
+        // Apply CRT shader effect to sourceTexture
+        [encoder setRenderPipelineState:pipelineState];
+        [encoder setVertexBuffer:vertexBuffer offset:0 atIndex:0];
+        [encoder setFragmentTexture:metalTexture atIndex:0];
+        [encoder setFragmentSamplerState:sampler atIndex:0];
+
+        // Draw fullscreen quad with CRT effect directly to screen
+        [encoder drawPrimitives:MTLPrimitiveTypeTriangleStrip vertexStart:0 vertexCount:4];
+
+        static int successCount = 0;
+        if (successCount++ < 3) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Applied CRT post-processing (attempt %d) - texture size: %lux%lu",
+                       successCount, [metalTexture width], [metalTexture height]);
+        }
+    } else {
+        // Fallback: render normally without shaders
+        SDL_RenderTexture(renderer, sourceTexture, nullptr, nullptr);
+
+        static int fallbackCount = 0;
+        if (fallbackCount++ < 3) {
+            SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "Failed to get Metal command encoder for post-processing - fallback rendering");
+        }
+    }
+
+    SDL_RenderPresent(renderer);
+}
+
+void cleanupMetal() {
+    // Release Metal objects (ARC handles most of this automatically)
+    pipelineState = nullptr;
+    backBufferTexture = nullptr;
+    gameCanvasTexture = nullptr;
+    vertexBuffer = nullptr;
+    sampler = nullptr;
+    device = nullptr;
+    renderer = nullptr;
+
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Metal shader system cleaned up");
+}
+
+} // namespace metal
+} // namespace shader
+
+#endif // __APPLE__

source/screen.cpp

@@ -44,8 +44,21 @@ Screen::Screen()
     initSDLVideo();
 
     // Crea la textura de destino
+#ifdef __APPLE__
+    const auto render_name = SDL_GetRendererName(renderer_);
+    if (render_name && !strncmp(render_name, "metal", 5)) {
+        // Usar nuestra propia Metal texture como render target
+        game_canvas_ = shader::metal::createMetalRenderTarget(renderer_, param.game.width, param.game.height);
+        SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Using custom Metal render target for game_canvas_");
+    } else {
+        // Fallback para otros renderers
+        game_canvas_ = SDL_CreateTexture(renderer_, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, param.game.width, param.game.height);
+        SDL_SetTextureScaleMode(game_canvas_, SDL_SCALEMODE_NEAREST);
+    }
+#else
     game_canvas_ = SDL_CreateTexture(renderer_, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, param.game.width, param.game.height);
     SDL_SetTextureScaleMode(game_canvas_, SDL_SCALEMODE_NEAREST);
+#endif
 
     // Crea el objeto de texto
     createText();
@@ -99,7 +112,18 @@ void Screen::renderPresent() {
     clean();
 
     if (Options::video.shaders) {
+#ifdef __APPLE__
+        const auto render_name = SDL_GetRendererName(renderer_);
+        if (render_name && !strncmp(render_name, "metal", 5)) {
+            // Use Metal post-processing with our custom render target
+            shader::metal::renderWithPostProcessing(renderer_, game_canvas_);
+        } else {
+            // Fallback to standard shader system for non-Metal renderers
+            shader::render();
+        }
+#else
         shader::render();
+#endif
     } else {
         SDL_RenderTexture(renderer_, game_canvas_, nullptr, nullptr);
         SDL_RenderPresent(renderer_);
@@ -296,17 +320,29 @@ auto Screen::initSDLVideo() -> bool {
     // Obtener información de la pantalla
     getDisplayInfo();
 
+#ifdef __APPLE__
+    // Configurar hint para Metal
+    if (!SDL_SetHint(SDL_HINT_RENDER_DRIVER, "metal")) {
+        SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
+            "Warning: Failed to set Metal hint!");
+    }
+    // Configurar flags para la creación de la ventana
+    SDL_WindowFlags window_flags = SDL_WINDOW_METAL;
+#else  // NOT APPLE
     // Configurar hint para OpenGL
     if (!SDL_SetHint(SDL_HINT_RENDER_DRIVER, "opengl")) {
         SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
             "Warning: Failed to set OpenGL hint!");
     }
-
-    // Crear ventana
+    // Configurar flags para la creación de la ventana
     SDL_WindowFlags window_flags = SDL_WINDOW_OPENGL;
+#endif
+    // Configurar flags para la creación de la ventana
     if (Options::video.fullscreen) {
         window_flags |= SDL_WINDOW_FULLSCREEN;
     }
+
+    // Crear ventana
     window_ = SDL_CreateWindow(
         Options::window.caption.c_str(),
         param.game.width * Options::window.zoom,