mirror of
https://github.com/italicsjenga/slang-shaders.git
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a53683a1ad
- Rename old catmull-rom-fast to catmull-rom; - Add new catmull-rom-fast shader; - Delete old b-spline-fast as it behaved exactly like bilinear; - Add new b-spline-fast shaders; - Add anti-ringing code to bicubic fast shaders.
103 lines
3.5 KiB
Plaintext
103 lines
3.5 KiB
Plaintext
#version 450
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/*
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Bicubic Catmull-Rom 9 taps (Fast) - ported by Hyllian - 2020
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The following code is licensed under the MIT license: https://gist.github.com/TheRealMJP/bc503b0b87b643d3505d41eab8b332ae
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Ported from code: https://gist.github.com/TheRealMJP/c83b8c0f46b63f3a88a5986f4fa982b1
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Samples a texture with Catmull-Rom filtering, using 9 texture fetches instead of 16.
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See http://vec3.ca/bicubic-filtering-in-fewer-taps/ for more details
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ATENTION: This code only work using LINEAR filter sampling set on Retroarch!
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*/
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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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#define mul(c,d) (d*c)
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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;
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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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void main()
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{
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// We're going to sample a a 4x4 grid of texels surrounding the target UV coordinate. We'll do this by rounding
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// down the sample location to get the exact center of our "starting" texel. The starting texel will be at
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// location [1, 1] in the grid, where [0, 0] is the top left corner.
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vec2 samplePos = vTexCoord * params.SourceSize.xy;
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vec2 texPos1 = floor(samplePos - 0.5) + 0.5;
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// Compute the fractional offset from our starting texel to our original sample location, which we'll
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// feed into the Catmull-Rom spline function to get our filter weights.
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vec2 f = samplePos - texPos1;
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// Compute the Catmull-Rom weights using the fractional offset that we calculated earlier.
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// These equations are pre-expanded based on our knowledge of where the texels will be located,
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// which lets us avoid having to evaluate a piece-wise function.
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vec2 w0 = f * (-0.5 + f * (1.0 - 0.5 * f));
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vec2 w1 = 1.0 + f * f * (-2.5 + 1.5 * f);
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vec2 w2 = f * (0.5 + f * (2.0 - 1.5 * f));
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vec2 w3 = f * f * (-0.5 + 0.5 * f);
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// vec2 w3 = 1.0 - w0 - w1 - w2;
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// Work out weighting factors and sampling offsets that will let us use bilinear filtering to
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// simultaneously evaluate the middle 2 samples from the 4x4 grid.
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vec2 w12 = w1 + w2;
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vec2 offset12 = w2 / (w1 + w2);
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// Compute the final UV coordinates we'll use for sampling the texture
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vec2 texPos0 = texPos1 - 1.;
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vec2 texPos3 = texPos1 + 2.;
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vec2 texPos12 = texPos1 + offset12;
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texPos0 *= params.SourceSize.zw;
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texPos3 *= params.SourceSize.zw;
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texPos12 *= params.SourceSize.zw;
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vec4 c00 = texture(Source, vec2(texPos0.x, texPos0.y));
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vec4 c10 = texture(Source, vec2(texPos12.x, texPos0.y));
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vec4 c20 = texture(Source, vec2(texPos3.x, texPos0.y));
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vec4 c01 = texture(Source, vec2(texPos0.x, texPos12.y));
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vec4 c11 = texture(Source, vec2(texPos12.x, texPos12.y));
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vec4 c21 = texture(Source, vec2(texPos3.x, texPos12.y));
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vec4 c02 = texture(Source, vec2(texPos0.x, texPos3.y));
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vec4 c12 = texture(Source, vec2(texPos12.x, texPos3.y));
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vec4 c22 = texture(Source, vec2(texPos3.x, texPos3.y));
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vec3 wx = vec3(w0.x, w12.x, w3.x);
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vec3 wy = vec3(w0.y, w12.y, w3.y);
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vec4 c1 = mul(wx, mat3x4(c00, c10, c20));
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vec4 c2 = mul(wx, mat3x4(c01, c11, c21));
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vec4 c3 = mul(wx, mat3x4(c02, c12, c22));
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FragColor = mul(wy, mat3x4(c1, c2, c3));
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} |