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thebookofshaders/10/tmp/matrix.frag

49 lines
1.2 KiB
GLSL

// Author @patriciogv - 2015
// http://patriciogonzalezvivo.com
#ifdef GL_ES
precision mediump float;
#endif
uniform vec2 u_resolution;
uniform float u_time;
float random(in float x){ return fract(sin(x)*43758.5453); }
float random(in vec2 st){ return fract(sin(dot(st.xy ,vec2(12.9898,78.233))) * 43758.5453); }
float randomChar(vec2 outer,vec2 inner){
float grid = 5.;
vec2 margin = vec2(.2,.05);
vec2 borders = step(margin,inner)*step(margin,1.-inner);
vec2 ipos = floor(inner*grid);
vec2 fpos = fract(inner*grid);
return step(.5,random(outer*64.+ipos)) * borders.x * borders.y * step(0.01,fpos.x) * step(0.01,fpos.y);
}
void main(){
vec2 st = gl_FragCoord.st/u_resolution.xy;
if (u_resolution.x > u_resolution.y) {
st.x *= u_resolution.x/u_resolution.y;
} else {
st.y *= u_resolution.y/u_resolution.y;
}
vec3 color = vec3(0.0);
float rows = 1.0;
// rows = 3.0;
rows = 12.0;
//rows = 24.0;
vec2 ipos = floor(st*rows);
vec2 fpos = fract(st*rows);
ipos += vec2(0.,floor(u_time*20.*random(ipos.x+1.)));
float pct = 1.0;
pct *= randomChar(ipos,fpos);
// pct *= random(ipos);
color = vec3(pct);
gl_FragColor = vec4( color , 1.0);
}