mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
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40 lines
1.0 KiB
GLSL
40 lines
1.0 KiB
GLSL
// Author @patriciogv - 2015
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// http://patriciogonzalezvivo.com
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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 vec2 u_mouse;
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uniform float u_time;
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float random (in float x) { return fract(sin(x)*1e4); }
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float random (in vec2 _st) { return fract(sin(dot(_st.xy, vec2(12.9898,78.233)))* 43758.5453123);}
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void main() {
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vec2 st = gl_FragCoord.xy/u_resolution.xy;
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st.x *= u_resolution.x/u_resolution.y;
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st *= vec2(100.0,50.);
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vec2 ipos = floor(st); // integer
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vec2 fpos = fract(st); // fraction
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vec2 vel = floor(vec2(u_time*10.)); // time
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vel *= vec2(-1.,0.); // direction
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vel *= (step(1., mod(ipos.y,2.0))-0.5)*2.; // Oposite directions
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vel *= random(ipos.y); // random speed
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// Move
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ipos += floor(vel);
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// Assign a random value base on the integer coord
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float pct = 1.0;
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pct *= random(ipos);
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pct *= step(.1,fpos.x)*step(.1,fpos.y); // margin
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pct = step(0.001+u_mouse.x/u_resolution.x,pct); // threshold
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gl_FragColor = vec4(vec3(pct),1.0);
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} |