thebookofshaders/07/arrow.frag
Patricio Gonzalez Vivo 46b34bccc8 adding arrow
2015-04-15 15:30:08 -04:00

31 lines
660 B
GLSL

// Author @patriciogv - 2015
// http://patriciogonzalezvivo.com
#ifdef GL_ES
precision mediump float;
#endif
#define PI 3.14159265359
#define TWO_PI 6.28318530718
uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;
float shape(vec2 st, int N){
st = st *2.-1.;
float a = atan(st.x,st.y)+PI;
float r = TWO_PI/float(N);
return cos(floor(.5+a/r)*r-a)*length(st);
}
void main(){
vec2 st = gl_FragCoord.xy/u_resolution.xy;
st.x *= u_resolution.x/u_resolution.y;
vec3 color = vec3(0.0);
float d = 0.0;
d = min(shape(st,3),shape(st+vec2(0.,0.2),4));
gl_FragColor = vec4(vec3(1.0-smoothstep(.2,.25,d)),1.0);
}