mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
synced 2024-11-08 01:10:27 +00:00
49 lines
1.2 KiB
GLSL
49 lines
1.2 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 float u_time;
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// Based on https://www.shadertoy.com/view/4sSSzG
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float triangleDF(vec2 _st,
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vec2 _p0, vec2 _p1, vec2 _p2){
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vec3 e0, e1, e2;
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e0.xy = normalize(_p1 - _p0).yx * vec2(+1.0, -1.0);
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e1.xy = normalize(_p2 - _p1).yx * vec2(+1.0, -1.0);
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e2.xy = normalize(_p0 - _p2).yx * vec2(+1.0, -1.0);
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e0.z = dot(e0.xy, _p0);
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e1.z = dot(e1.xy, _p1);
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e2.z = dot(e2.xy, _p2);
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float a = max(0.0, dot(e0.xy, _st) - e0.z);
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float b = max(0.0, dot(e1.xy, _st) - e1.z);
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float c = max(0.0, dot(e2.xy, _st) - e2.z);
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return length(vec3(a, b, c)*2.0);
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}
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void main(){
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vec2 st = gl_FragCoord.xy/u_resolution.xy;
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vec3 color = vec3(0.0);
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// Distance Field in 3 channels
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float df = triangleDF(st,
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vec2(0.40,0.45),
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vec2(0.60,0.45),
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vec2(0.5,0.60));
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color = vec3(df);
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// Make a shape of it
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float size = fract(u_time*0.2);
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float border = 0.025;
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color.rb += smoothstep(size+border,size+1e-7,df)-
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smoothstep(size+0.001,size+1e-7,df);
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gl_FragColor = vec4(color,1.0);
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} |