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