m

learning/shapes/triangle.frag

@@ -0,0 +1,32 @@
+#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;
+
+void main() {
+  vec2 st = gl_FragCoord.xy/u_resolution.xy;
+  st.x *= u_resolution.x/u_resolution.y; //wtf is this for? maybe it's to maintain aspect ratio
+  vec3 color = vec3(0.0);
+  float d = 0.0;
+  //Remap the space to -1 to 1
+  st = st*2.-1.;
+
+  // number of sides of your shape 
+  int N = 3;
+
+
+  // angle and radius from the current pixel
+  float a = atan(st.x,st.y)+PI;
+  float r = TWO_PI/float(N);
+  d = cos(floor(.5+a/r)*r-a)*length(st);
+
+  color = vec3(1.0-smoothstep(.4,.41,d));
+
+  gl_FragColor = vec4(color,1.0);
+}