convert mat4 exMatrix to a vec2 extrudeScale

The matrix was only be used to scale vec2s. We don't need a mat4 to do
that. This should be slightly faster

circle.vertex.glsl

@@ -1,7 +1,7 @@
 precision highp float;
 
 uniform mat4 u_matrix;
-uniform mat4 u_exmatrix;
+uniform vec2 u_extrude_scale;
 uniform float u_devicepixelratio;
 
 attribute vec2 a_pos;
@@ -64,14 +64,14 @@ void main(void) {
     // unencode the extrusion vector that we snuck into the a_pos vector
     v_extrude = vec2(mod(a_pos, 2.0) * 2.0 - 1.0);
 
-    vec4 extrude = u_exmatrix * vec4(v_extrude * radius, 0, 0);
+    vec2 extrude = v_extrude * radius * u_extrude_scale;
     // multiply a_pos by 0.5, since we had it * 2 in order to sneak
     // in extrusion data
     gl_Position = u_matrix * vec4(floor(a_pos * 0.5), 0, 1);
 
     // gl_Position is divided by gl_Position.w after this shader runs.
     // Multiply the extrude by it so that it isn't affected by it.
-    gl_Position += extrude * gl_Position.w;
+    gl_Position.xy += extrude * gl_Position.w;
 
 #ifdef ATTRIBUTE_A_COLOR
     v_color = a_color / 255.0;

icon.vertex.glsl

@@ -9,10 +9,11 @@ attribute vec4 a_data2;
 // matrix is for the vertex position, exmatrix is for rotating and projecting
 // the extrusion vector.
 uniform mat4 u_matrix;
-uniform mat4 u_exmatrix;
+
 uniform mediump float u_zoom;
 uniform bool u_skewed;
 uniform float u_extra;
+uniform vec2 u_extrude_scale;
 
 uniform vec2 u_texsize;
 
@@ -26,18 +27,15 @@ void main() {
     mediump float a_minzoom = a_zoom[0];
     mediump float a_maxzoom = a_zoom[1];
 
-    float a_fadedist = 10.0;
-
     // u_zoom is the current zoom level adjusted for the change in font size
     mediump float z = 2.0 - step(a_minzoom, u_zoom) - (1.0 - step(a_maxzoom, u_zoom));
 
+    vec2 extrude = u_extrude_scale * (a_offset / 64.0);
     if (u_skewed) {
-        vec4 extrude = u_exmatrix * vec4(a_offset / 64.0, 0, 0);
-        gl_Position = u_matrix * vec4(a_pos + extrude.xy, 0, 1);
+        gl_Position = u_matrix * vec4(a_pos + extrude, 0, 1);
         gl_Position.z += z * gl_Position.w;
     } else {
-        vec4 extrude = u_exmatrix * vec4(a_offset / 64.0, z, 0);
-        gl_Position = u_matrix * vec4(a_pos, 0, 1) + extrude;
+        gl_Position = u_matrix * vec4(a_pos, 0, 1) + vec4(extrude, 0, 0);
     }
 
     v_tex = a_tex / u_texsize;

sdf.vertex.glsl

@@ -9,11 +9,11 @@ attribute vec4 a_data2;
 // matrix is for the vertex position, exmatrix is for rotating and projecting
 // the extrusion vector.
 uniform mat4 u_matrix;
-uniform mat4 u_exmatrix;
 
 uniform mediump float u_zoom;
 uniform bool u_skewed;
 uniform float u_extra;
+uniform vec2 u_extrude_scale;
 
 uniform vec2 u_texsize;
 
@@ -31,13 +31,12 @@ void main() {
     // u_zoom is the current zoom level adjusted for the change in font size
     mediump float z = 2.0 - step(a_minzoom, u_zoom) - (1.0 - step(a_maxzoom, u_zoom));
 
+    vec2 extrude = u_extrude_scale * (a_offset / 64.0);
     if (u_skewed) {
-        vec4 extrude = u_exmatrix * vec4(a_offset / 64.0, 0, 0);
-        gl_Position = u_matrix * vec4(a_pos + extrude.xy, 0, 1);
+        gl_Position = u_matrix * vec4(a_pos + extrude, 0, 1);
         gl_Position.z += z * gl_Position.w;
     } else {
-        vec4 extrude = u_exmatrix * vec4(a_offset / 64.0, z, 0);
-        gl_Position = u_matrix * vec4(a_pos, 0, 1) + extrude;
+        gl_Position = u_matrix * vec4(a_pos, 0, 1) + vec4(extrude, 0, 0);
     }
 
     // position of y on the screen