mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
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35 lines
951 B
GLSL
35 lines
951 B
GLSL
// Yosuke SAKAI(@flush_11, http://yosuke-sakai.com/)
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// Drawing multiple shaping functions on gradient background
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// A sample for the book of the shaders.
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// http://thebookofshaders.com/05/
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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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// Plot a line on Y using a value between 0.0-1.0
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float plot(vec2 st, float pct){
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return smoothstep( pct-0.02, pct, st.y) -
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smoothstep( pct, pct+0.02, st.y);
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}
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void main() {
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vec2 st = gl_FragCoord.xy / u_resolution;
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//backgoud gradient
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vec3 bkcolor = vec3(st.x);
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// Plot a lines
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float pct1 = plot(st, st.x);
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float pct2 = plot(st,pow(st.x, 0.5));
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float pct3 = plot(st, pow(st.x, 2.0));
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vec3 color = (1.0 - pct1) * (1.0 - pct2) * (1.0 - pct3) * bkcolor + pct1 * vec3(1.0, 0.0, 0.0) + pct2 * vec3(0.0, 1.0, 0.0) + pct3 * vec3(0.0, 1.0, 1.0);
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gl_FragColor = vec4(color, 1.0);
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}
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