mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
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42 lines
845 B
GLSL
42 lines
845 B
GLSL
// Author @patriciogv ( patriciogonzalezvivo.com ) - 2015
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#ifdef GL_ES
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precision mediump float;
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#endif
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uniform vec2 u_resolution;
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uniform float u_time;
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vec2 tile (vec2 st, float _zoom) {
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st *= _zoom;
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return fract(st);
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}
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vec2 seamlessTile(vec2 st){
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st *= 2.0;
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float index = 0.0;
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index += step(1., mod(st.x,2.0));
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index += step(1., mod(st.y,2.0))*2.0;
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st = fract(st);
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if(index == 1.0){
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st.x = 1.0-st.x;
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} else if(index == 2.0){
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st.y = 1.0-st.y;
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} else if(index == 3.0){
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st = 1.0-st;
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}
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return st;
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}
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void main (void) {
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vec2 st = gl_FragCoord.xy/u_resolution.xy;
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st = tile(st,1.0);
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st = seamlessTile(st);
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// step(st.x,st.y) just makes a b&w triangles
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// but you can use whatever design you want.
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gl_FragColor = vec4(vec3(step(st.x,st.y)),1.0);
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}
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