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

js/geo/transform.js

@@ -131,10 +131,7 @@ Transform.prototype = {
         this.width = width;
         this.height = height;
 
-        // The extrusion matrix
-        this.exMatrix = mat4.create();
-        mat4.ortho(this.exMatrix, 0, width, height, 0, 0, -1);
-
+        this.pixelsToGLUnits = [2 / width, -2 / height];
         this._calcProjMatrix();
         this._constrain();
     },

js/render/draw_circle.js

@@ -27,7 +27,7 @@ function drawCircles(painter, source, layer, coords) {
 
         var program = painter.useProgram('circle', bucket.getProgramMacros('circle', layer));
 
-        gl. uniformMatrix4fv(program.u_exmatrix, false, painter.transform.exMatrix);
+        gl.uniform2fv(program.u_extrude_scale, painter.transform.pixelsToGLUnits);
         gl.uniform1f(program.u_blur, layer.paint['circle-blur']);
         gl.uniform1f(program.u_devicepixelratio, browser.devicePixelRatio);
         gl.uniform1f(program.u_opacity, layer.paint['circle-opacity']);

js/render/draw_symbol.js

@@ -1,7 +1,5 @@
 'use strict';
 
-var mat4 = require('gl-matrix').mat4;
-
 var browser = require('../util/browser');
 var drawCollisionDebug = require('./draw_collision_debug');
 var util = require('../util/util');
@@ -113,24 +111,23 @@ function drawSymbol(painter, layer, posMatrix, tile, bucket, elementGroups, isTe
 
     var tr = painter.transform;
     var alignedWithMap = rotationAlignment === 'map';
+
+    var fontSize = size;
+    var defaultSize = isText ? 24 : 1;
+    var fontScale = fontSize / defaultSize;
+
     var skewed = alignedWithMap;
-    var exMatrix, s, gammaScale;
+    var extrudeScale, s, gammaScale;
 
     if (skewed) {
-        exMatrix = mat4.create();
-        s = pixelsToTileUnits(tile, 1, painter.transform.zoom);
+        s = pixelsToTileUnits(tile, 1, painter.transform.zoom) * fontScale;
         gammaScale = 1 / Math.cos(tr._pitch);
+        extrudeScale = [s, s];
     } else {
-        exMatrix = mat4.clone(painter.transform.exMatrix);
-        s = painter.transform.altitude;
+        s = painter.transform.altitude * fontScale;
         gammaScale = 1;
+        extrudeScale = [ tr.pixelsToGLUnits[0] * s, tr.pixelsToGLUnits[1] * s];
     }
-    mat4.scale(exMatrix, exMatrix, [s, s, 1]);
-
-    var fontSize = size;
-    var defaultSize = isText ? 24 : 1;
-    var fontScale = fontSize / defaultSize;
-    mat4.scale(exMatrix, exMatrix, [ fontScale, fontScale, 1 ]);
 
     // calculate how much longer the real world distance is at the top of the screen
     // than at the middle of the screen.
@@ -145,7 +142,6 @@ function drawSymbol(painter, layer, posMatrix, tile, bucket, elementGroups, isTe
 
     var program = painter.useProgram(sdf ? 'sdf' : 'icon');
     gl.uniformMatrix4fv(program.u_matrix, false, painter.translatePosMatrix(posMatrix, tile, translate, translateAnchor));
-    gl.uniformMatrix4fv(program.u_exmatrix, false, exMatrix);
 
     var texsize;
     if (isText) {
@@ -169,6 +165,7 @@ function drawSymbol(painter, layer, posMatrix, tile, bucket, elementGroups, isTe
     gl.uniform2fv(program.u_texsize, texsize);
     gl.uniform1i(program.u_skewed, skewed);
     gl.uniform1f(program.u_extra, extra);
+    gl.uniform2fv(program.u_extrude_scale, extrudeScale);
 
     // adjust min/max zooms for variable font sizes
     var zoomAdjust = Math.log(fontSize / elementGroups.adjustedSize) / Math.LN2 || 0;

shaders/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;

shaders/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;

shaders/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