mirror of
https://github.com/Ttanasart-pt/Pixel-Composer.git
synced 2024-11-14 06:23:55 +01:00
108 lines
2.9 KiB
GLSL
108 lines
2.9 KiB
GLSL
//
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// Perspective transform
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//
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varying vec2 v_vTexcoord;
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varying vec4 v_vColour;
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uniform vec2 p0;
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uniform vec2 p1;
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uniform vec2 p2;
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uniform vec2 p3;
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uniform vec2 dimension;
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/////////////// SAMPLING ///////////////
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const float PI = 3.14159265358979323846;
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uniform int interpolation;
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uniform vec2 sampleDimension;
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const int RSIN_RADIUS = 1;
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float sinc ( float x ) { return x == 0.? 1. : sin(x * PI) / (x * PI); }
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vec4 texture2D_rsin( sampler2D texture, vec2 uv ) {
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vec2 tx = 1.0 / sampleDimension;
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vec2 p = uv * sampleDimension - vec2(0.5);
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vec4 sum = vec4(0.0);
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float weights = 0.;
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for (int x = -RSIN_RADIUS; x <= RSIN_RADIUS; x++)
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for (int y = -RSIN_RADIUS; y <= RSIN_RADIUS; y++) {
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float a = length(vec2(float(x), float(y))) / float(RSIN_RADIUS);
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if(a > 1.) continue;
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float w = sinc(a * PI * tx.x) * sinc(a * PI * tx.y);
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vec2 offset = vec2(float(x), float(y)) * tx;
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vec4 sample = texture2D(texture, (p + offset + vec2(0.5)) / sampleDimension);
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sum += w * sample;
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weights += w;
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}
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return sum / weights;
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}
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vec4 texture2D_bicubic( sampler2D texture, vec2 uv ) {
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uv = uv * sampleDimension + 0.5;
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vec2 iuv = floor( uv );
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vec2 fuv = fract( uv );
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uv = iuv + fuv * fuv * (3.0 - 2.0 * fuv);
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uv = (uv - 0.5) / sampleDimension;
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return texture2D( texture, uv );
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}
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vec4 texture2Dintp( sampler2D texture, vec2 uv ) {
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if(interpolation == 2) return texture2D_bicubic( texture, uv );
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else if(interpolation == 3) return texture2D_rsin( texture, uv );
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return texture2D( texture, uv );
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}
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/////////////// SAMPLING ///////////////
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float unmix( float st, float ed, float val) {
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return (val - st) / (ed - st);
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}
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// 2 1
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// 3 0
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void main() {
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float px = v_vTexcoord.x;
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float py = v_vTexcoord.y;
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float u, v;
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vec2 uv;
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if (abs(p3.y - p0.y) < 1. / dimension.y && abs(p2.y - p1.y) < 1. / dimension.y) { // trapezoid edge case
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float t = (py - p2.y) / (p3.y - p2.y);
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u = unmix(mix(p3.x, p2.x, 1. - t), mix(p0.x, p1.x, 1. - t), px);
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v = t;
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uv = vec2(u, v);
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} else if(abs(p2.x - p3.x) < 1. / dimension.x && abs(p1.x - p0.x) < 1. / dimension.x) { // trapezoid edge case
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float t = (px - p2.x) / (p1.x - p2.x);
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u = t;
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v = unmix(mix(p1.y, p2.y, 1. - t), mix(p0.y, p3.y, 1. - t), py);
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uv = vec2(u, v);
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} else {
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vec2 A = (p3 - p0) - (p2 - p1);
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vec2 B = (p0 - p1);
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vec2 C = (p2 - p1);
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vec2 D = p1;
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float c1 = (B.y * C.x) + (A.y * D.x) - (B.x * C.y) - (A.x * D.y);
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float c2 = (B.y * D.x) - (B.x * D.y);
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float _A = (A.y * C.x) - (A.x * C.y);
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float _B = (A.x * py) + c1 - (A.y * px);
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float _C = (B.x * py) + c2 - (B.y * px);
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u = A == vec2(0.)? 0. : (-_B - sqrt(_B * _B - 4.0 * _A * _C)) / (_A * 2.0);
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v = (u * A.x + B.x) == 0.? 0. : (px - (u * C.x) - D.x) / (u * A.x + B.x);
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uv = vec2(1. - u, v);
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}
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if(uv.x >= 0. && uv.y >= 0. && uv.x <= 1. && uv.y <= 1.)
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gl_FragColor = texture2Dintp( gm_BaseTexture, uv );
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else
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gl_FragColor = vec4(0.);
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} |