Updated shaders with comments

shaders/glsl100/swirl.fs

@@ -2,28 +2,32 @@
 
 precision mediump float;
 
+// Input vertex attributes (from vertex shader)
 varying vec2 fragTexCoord;
+varying vec4 fragColor;
 
+// Input uniform values
 uniform sampler2D texture0;
 uniform vec4 fragTintColor;
 
 // NOTE: Add here your custom variables
 
-const float renderWidth = 1280; 
-const float renderHeight = 720; 
+const float renderWidth = 800.0;      // HARDCODED for example!
+const float renderHeight = 480.0;     // Use uniforms instead...
 
 float radius = 250.0;
 float angle = 0.8;
 
-uniform vec2 center = vec2(200, 200);
+uniform vec2 center = vec2(200.0, 200.0);
 
-void main (void)
+void main()
 {
     vec2 texSize = vec2(renderWidth, renderHeight);
     vec2 tc = fragTexCoord*texSize;
     tc -= center;
-    float dist = length(tc);
     
+    float dist = length(tc);
+
     if (dist < radius) 
     {
         float percent = (radius - dist)/radius;
@@ -33,7 +37,7 @@ void main (void)
         
         tc = vec2(dot(tc, vec2(c, -s)), dot(tc, vec2(s, c)));
     }
-    
+
     tc += center;
     vec3 color = texture2D(texture0, tc/texSize).rgb;