137 lines
4.6 KiB
GLSL
137 lines
4.6 KiB
GLSL
#version 450
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// Vulkan GLSL fragment shader — PostFX effects
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// Used for SDL3 GPU API (SPIR-V path, Win/Linux).
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// Compile: glslc postfx.frag -o postfx.frag.spv
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// xxd -i postfx.frag.spv > ../../source/core/rendering/sdl3gpu/postfx_frag_spv.h
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//
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// PostFXUniforms must match exactly the C++ struct in sdl3gpu_shader.hpp
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// (8 floats, 32 bytes, std140/scalar layout).
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layout(location = 0) in vec2 v_uv;
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layout(location = 0) out vec4 out_color;
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layout(set = 2, binding = 0) uniform sampler2D scene;
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layout(set = 3, binding = 0) uniform PostFXUniforms {
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float vignette_strength;
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float chroma_strength;
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float scanline_strength;
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float screen_height;
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float mask_strength;
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float gamma_strength;
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float curvature;
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float bleeding;
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float pixel_scale; // physical pixels per logical pixel (vh / tex_height_)
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float time; // seconds since SDL init (for future animated effects)
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float pad0; // padding — 48 bytes total (3 × 16)
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float pad1;
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} u;
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// YCbCr helpers for NTSC bleeding
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vec3 rgb_to_ycc(vec3 rgb) {
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return vec3(
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0.299*rgb.r + 0.587*rgb.g + 0.114*rgb.b,
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-0.169*rgb.r - 0.331*rgb.g + 0.500*rgb.b + 0.5,
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0.500*rgb.r - 0.419*rgb.g - 0.081*rgb.b + 0.5
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);
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}
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vec3 ycc_to_rgb(vec3 ycc) {
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float y = ycc.x;
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float cb = ycc.y - 0.5;
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float cr = ycc.z - 0.5;
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return clamp(vec3(
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y + 1.402*cr,
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y - 0.344*cb - 0.714*cr,
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y + 1.772*cb
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), 0.0, 1.0);
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}
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void main() {
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vec2 uv = v_uv;
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// Curvatura barrel CRT
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if (u.curvature > 0.0) {
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vec2 c = uv - 0.5;
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float rsq = dot(c, c);
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vec2 dist = vec2(0.05, 0.1) * u.curvature;
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vec2 barrelScale = vec2(1.0) - 0.23 * dist;
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c += c * (dist * rsq);
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c *= barrelScale;
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if (abs(c.x) >= 0.5 || abs(c.y) >= 0.5) {
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out_color = vec4(0.0, 0.0, 0.0, 1.0);
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return;
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}
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uv = c + 0.5;
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}
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// Muestra base
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vec3 base = texture(scene, uv).rgb;
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// Sangrado NTSC — difuminado horizontal de crominancia
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vec3 colour;
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if (u.bleeding > 0.0) {
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float tw = float(textureSize(scene, 0).x);
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vec3 ycc = rgb_to_ycc(base);
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vec3 ycc_l2 = rgb_to_ycc(texture(scene, uv - vec2(2.0/tw, 0.0)).rgb);
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vec3 ycc_l1 = rgb_to_ycc(texture(scene, uv - vec2(1.0/tw, 0.0)).rgb);
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vec3 ycc_r1 = rgb_to_ycc(texture(scene, uv + vec2(1.0/tw, 0.0)).rgb);
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vec3 ycc_r2 = rgb_to_ycc(texture(scene, uv + vec2(2.0/tw, 0.0)).rgb);
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ycc.yz = (ycc_l2.yz + ycc_l1.yz*2.0 + ycc.yz*2.0 + ycc_r1.yz*2.0 + ycc_r2.yz) / 8.0;
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colour = mix(base, ycc_to_rgb(ycc), u.bleeding);
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} else {
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colour = base;
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}
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// Aberración cromática
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float ca = u.chroma_strength * 0.005;
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colour.r = texture(scene, uv + vec2(ca, 0.0)).r;
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colour.b = texture(scene, uv - vec2(ca, 0.0)).b;
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// Corrección gamma (linealizar antes de scanlines, codificar después)
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if (u.gamma_strength > 0.0) {
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vec3 lin = pow(colour, vec3(2.4));
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colour = mix(colour, lin, u.gamma_strength);
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}
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// Scanlines — 1 pixel físico oscuro por fila lógica.
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// Usa uv.y (independiente del offset de letterbox) con pixel_scale para
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// calcular la posición dentro de la fila en coordenadas físicas.
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// 3x: 1 dark + 2 bright. 4x: 1 dark + 3 bright.
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// bright=3.5×, dark floor=0.42 (mantiene aspecto CRT original).
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if (u.scanline_strength > 0.0) {
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float ps = max(1.0, round(u.pixel_scale));
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float frac_in_row = fract(uv.y * u.screen_height);
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float row_pos = floor(frac_in_row * ps);
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float is_dark = step(ps - 1.0, row_pos);
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float scan = mix(3.5, 0.42, is_dark);
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colour *= mix(1.0, scan, u.scanline_strength);
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}
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if (u.gamma_strength > 0.0) {
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vec3 enc = pow(colour, vec3(1.0 / 2.2));
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colour = mix(colour, enc, u.gamma_strength);
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}
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// Viñeta
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vec2 d = uv - 0.5;
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float vignette = 1.0 - dot(d, d) * u.vignette_strength;
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colour *= clamp(vignette, 0.0, 1.0);
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// Máscara de fósforo RGB — después de scanlines (orden original):
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// filas brillantes saturadas → máscara invisible, filas oscuras → RGB visible.
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if (u.mask_strength > 0.0) {
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float whichMask = fract(gl_FragCoord.x * 0.3333333);
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vec3 mask = vec3(0.80);
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if (whichMask < 0.3333333)
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mask.x = 1.0;
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else if (whichMask < 0.6666666)
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mask.y = 1.0;
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else
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mask.z = 1.0;
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colour = mix(colour, colour * mask, u.mask_strength);
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}
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out_color = vec4(colour, 1.0);
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}
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