deze versie cared nie om aspect ratio. kmoet die truc onthouden

learning/shapes/distancefield.frag

@@ -0,0 +1,31 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+#define PI 3.14159265359
+
+float circle(in vec2 st, in float radius){
+  vec2 dist = st-vec2(.5);
+  return 1.-smoothstep(radius-(radius*.01),
+                       radius+(radius*.01),
+                       dot(dist,dist)*4.);
+}
+
+
+void main() {
+  vec2 st = gl_FragCoord.xy/u_resolution;
+  st.x *= u_resolution.x/u_resolution.y;
+  vec3 color = vec3(1.0);
+  float alpha = 0.;
+  float d = 0.0;
+  // remaps space to -1 1
+  st = st *2.-1.;
+  d = length(abs(st)-.3);
+  
+  
+
+  gl_FragColor = vec4(color, alpha);
+}