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https://github.com/italicsjenga/slang-shaders.git
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89 lines
2.2 KiB
Plaintext
89 lines
2.2 KiB
Plaintext
#version 450
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// EPX (Eric's Pixel Scaler)
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// based on the description from Wikipedia:
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// https://en.wikipedia.org/wiki/Pixel-art_scaling_algorithms#EPX/Scale2%C3%97/AdvMAME2%C3%97
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// adapted for slang by hunterk
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// license GPL, I think
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layout(push_constant) uniform Push
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{
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vec4 SourceSize;
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vec4 OriginalSize;
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vec4 OutputSize;
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uint FrameCount;
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} params;
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layout(std140, set = 0, binding = 0) uniform UBO
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{
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mat4 MVP;
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} global;
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#pragma stage vertex
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layout(location = 0) in vec4 Position;
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layout(location = 1) in vec2 TexCoord;
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layout(location = 0) out vec2 vTexCoord;
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void main()
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{
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gl_Position = global.MVP * Position;
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vTexCoord = TexCoord * 1.00001;
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}
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#pragma stage fragment
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layout(location = 0) in vec2 vTexCoord;
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layout(location = 0) out vec4 FragColor;
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layout(set = 0, binding = 2) uniform sampler2D Source;
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bool same(vec3 B, vec3 A0){
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return all(equal(B, A0));
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}
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bool notsame(vec3 B, vec3 A0){
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return any(notEqual(B, A0));
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}
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// sample with coordinate offsets
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#define TEX(c,d) texture(Source, vTexCoord.xy + vec2(c,d) * params.SourceSize.zw).rgb
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void main()
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{
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// The algorithm looks at the current pixel and the 4 surrounding cardinal pixels
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// ___|_A_|___
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// _C_|_P_|_B_
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// | D |
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// Our current pixel, P
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vec3 P = TEX( 0., 0.);
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// Input pixels
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vec3 A = TEX( 0., 1.);
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vec3 B = TEX( 1., 0.);
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vec3 D = TEX( 0.,-1.);
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vec3 C = TEX(-1., 0.);
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// Output: 2x2 grid. Default to the current pixel color (Nearest magnification)
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// ___one_|_two___
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// three | four
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vec3 one = P;
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vec3 two = P;
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vec3 three = P;
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vec3 four = P;
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// EPX algorithm rules:
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// IF C==A AND C!=D AND A!=B => 1=A
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// IF A==B AND A!=C AND B!=D => 2=B
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// IF D==C AND D!=B AND C!=A => 3=C
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// IF B==D AND B!=A AND D!=C => 4=D
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one = (same(C, D) && notsame(C, A) && notsame(C, B)) ? C : P;
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two = (same(D, B) && notsame(D, C) && notsame(D, A)) ? D : P;
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three = (same(A, C) && notsame(A, B) && notsame(A, D)) ? A : P;
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four = (same(B, A) && notsame(B, D) && notsame(B, C)) ? B : P;
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vec2 px = fract(vTexCoord * params.SourceSize.xy);
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// split the texels into 4 and assign one of our output pixels to each
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FragColor.rgb = (px.x < 0.5) ? (px.y < 0.5 ? one : three) : (px.y < 0.5 ? two : four);
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FragColor.a = 1.0;
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}
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