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138 lines
4.4 KiB
138 lines
4.4 KiB
/*
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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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Modified to use 5 texture fetches
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*/
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#if defined(VERTEX)
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#if __VERSION__ >= 130
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#define COMPAT_VARYING out
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#define COMPAT_ATTRIBUTE in
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#define COMPAT_TEXTURE texture
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#else
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#define COMPAT_VARYING varying
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#define COMPAT_ATTRIBUTE attribute
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#define COMPAT_TEXTURE texture2D
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#endif
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#ifdef GL_ES
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#define COMPAT_PRECISION mediump
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precision COMPAT_PRECISION float;
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#else
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#define COMPAT_PRECISION
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#endif
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COMPAT_ATTRIBUTE vec4 VertexCoord;
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COMPAT_ATTRIBUTE vec4 COLOR;
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COMPAT_ATTRIBUTE vec4 TexCoord;
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COMPAT_VARYING vec4 COL0;
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COMPAT_VARYING vec4 TEX0;
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uniform mat4 MVPMatrix;
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uniform COMPAT_PRECISION int FrameDirection;
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uniform COMPAT_PRECISION int FrameCount;
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uniform COMPAT_PRECISION vec2 OutputSize;
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uniform COMPAT_PRECISION vec2 TextureSize;
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uniform COMPAT_PRECISION vec2 InputSize;
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void main()
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{
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gl_Position = MVPMatrix * VertexCoord;
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COL0 = COLOR;
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TEX0.xy = TexCoord.xy;
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}
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#elif defined(FRAGMENT)
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#if __VERSION__ >= 130
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#define COMPAT_VARYING in
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#define COMPAT_TEXTURE texture
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out mediump vec4 FragColor;
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#else
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#define COMPAT_VARYING varying
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#define FragColor gl_FragColor
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#define COMPAT_TEXTURE texture2D
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#endif
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#ifdef GL_ES
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#ifdef GL_FRAGMENT_PRECISION_HIGH
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precision highp float;
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#else
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precision mediump float;
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#endif
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#define COMPAT_PRECISION mediump
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#else
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#define COMPAT_PRECISION
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#endif
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uniform COMPAT_PRECISION int FrameDirection;
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uniform COMPAT_PRECISION int FrameCount;
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uniform COMPAT_PRECISION vec2 OutputSize;
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uniform COMPAT_PRECISION vec2 TextureSize;
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uniform COMPAT_PRECISION vec2 InputSize;
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uniform sampler2D Texture;
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COMPAT_VARYING vec4 TEX0;
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// compatibility #defines
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#define Source Texture
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#define vTexCoord TEX0.xy
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#define SourceSize vec4(TextureSize, 1.0 / TextureSize) //either TextureSize or InputSize
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#define outsize vec4(OutputSize, 1.0 / OutputSize)
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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 * 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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// 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 *= SourceSize.zw;
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texPos3 *= SourceSize.zw;
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texPos12 *= SourceSize.zw;
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float wtm = w12.x * w0.y;
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float wml = w0.x * w12.y;
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float wmm = w12.x * w12.y;
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float wmr = w3.x * w12.y;
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float wbm = w12.x * w3.y;
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vec3 result = vec3(0.0f);
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result += COMPAT_TEXTURE(Source, vec2(texPos12.x, texPos0.y)).rgb * wtm;
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result += COMPAT_TEXTURE(Source, vec2(texPos0.x, texPos12.y)).rgb * wml;
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result += COMPAT_TEXTURE(Source, vec2(texPos12.x, texPos12.y)).rgb * wmm;
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result += COMPAT_TEXTURE(Source, vec2(texPos3.x, texPos12.y)).rgb * wmr;
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result += COMPAT_TEXTURE(Source, vec2(texPos12.x, texPos3.y)).rgb * wbm;
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FragColor = vec4(result * (1./(wtm+wml+wmm+wmr+wbm)), 1.0);
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}
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#endif
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