mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
synced 2024-11-08 01:10:27 +00:00
46 lines
1.2 KiB
GLSL
46 lines
1.2 KiB
GLSL
// Author @patriciogv - 2015
|
|
// http://patriciogonzalezvivo.com
|
|
#ifdef GL_ES
|
|
precision mediump float;
|
|
#endif
|
|
|
|
#define PI 3.14159265358979323846
|
|
#define TWO_PI 6.28318530717958647693
|
|
|
|
uniform vec2 u_resolution;
|
|
uniform float u_time;
|
|
|
|
// Based on https://www.shadertoy.com/view/4sSSzG
|
|
float triangle (vec2 _st,
|
|
vec2 _p0, vec2 _p1, vec2 _p2,
|
|
float _smoothness){
|
|
vec3 e0, e1, e2;
|
|
|
|
e0.xy = normalize(_p1 - _p0).yx * vec2(+1.0, -1.0);
|
|
e1.xy = normalize(_p2 - _p1).yx * vec2(+1.0, -1.0);
|
|
e2.xy = normalize(_p0 - _p2).yx * vec2(+1.0, -1.0);
|
|
|
|
e0.z = dot(e0.xy, _p0) - _smoothness;
|
|
e1.z = dot(e1.xy, _p1) - _smoothness;
|
|
e2.z = dot(e2.xy, _p2) - _smoothness;
|
|
|
|
float a = max(0.0, dot(e0.xy, _st) - e0.z);
|
|
float b = max(0.0, dot(e1.xy, _st) - e1.z);
|
|
float c = max(0.0, dot(e2.xy, _st) - e2.z);
|
|
|
|
return smoothstep(_smoothness * 2.0,
|
|
1e-7,
|
|
length(vec3(a, b, c)));
|
|
}
|
|
|
|
void main(){
|
|
vec2 st = gl_FragCoord.xy/u_resolution.xy;
|
|
|
|
vec3 color = vec3( triangle(st,
|
|
vec2(0.0,0.15),
|
|
vec2(1.0,0.15),
|
|
vec2(0.5,0.88),
|
|
0.001) );
|
|
|
|
gl_FragColor = vec4(color,1.0);
|
|
} |