Merge pull request #16 from mapbox/vec4-icecream-float

vec4 => float for blur/opacity in circle shader

src/circle.fragment.glsl

@@ -7,16 +7,16 @@ precision mediump float;
 #endif
 
 #pragma mapbox: define lowp vec4 color
-#pragma mapbox: define lowp vec4 blur
-#pragma mapbox: define lowp vec4 opacity
+#pragma mapbox: define lowp float blur
+#pragma mapbox: define lowp float opacity
 
 varying vec2 v_extrude;
 varying lowp float v_antialiasblur;
 
 void main() {
     #pragma mapbox: initialize lowp vec4 color
-    #pragma mapbox: initialize lowp vec4 blur
-    #pragma mapbox: initialize lowp vec4 opacity
+    #pragma mapbox: initialize lowp float blur
+    #pragma mapbox: initialize lowp float opacity
 
     float t = smoothstep(1.0 - max(blur, v_antialiasblur), 1.0, length(v_extrude));
     gl_FragColor = color * (1.0 - t) * opacity;

src/circle.vertex.glsl

@@ -14,17 +14,17 @@ attribute vec2 a_pos;
 
 #pragma mapbox: define lowp vec4 color
 #pragma mapbox: define mediump float radius
-#pragma mapbox: define lowp vec4 blur
-#pragma mapbox: define lowp vec4 opacity
+#pragma mapbox: define lowp float blur
+#pragma mapbox: define lowp float opacity
 
 varying vec2 v_extrude;
 varying lowp float v_antialiasblur;
 
 void main(void) {
     #pragma mapbox: initialize lowp vec4 color
     #pragma mapbox: initialize mediump float radius
-    #pragma mapbox: initialize lowp vec4 blur
-    #pragma mapbox: initialize lowp vec4 opacity
+    #pragma mapbox: initialize lowp float blur
+    #pragma mapbox: initialize lowp float opacity
 
     // unencode the extrusion vector that we snuck into the a_pos vector
     v_extrude = vec2(mod(a_pos, 2.0) * 2.0 - 1.0);