optimize generateTempBuffers by more than an order of magitude

1 files changed, 7 insertions, 16 deletions

diff --git a/src/library_gl.js b/src/library_gl.js
index db81e358..adf9d611 100644
--- a/src/library_gl.js
+++ b/src/library_gl.js
@@ -1439,26 +1439,17 @@ var LibraryGL = {
     tempQuadIndexBuffer: null,
 
     generateTempBuffers: function() {
-      function ceilPower2(x) {
-        return Math.pow(2, Math.ceil(Math.log(x || 1)/Math.log(2)));
-      }
       this.tempBufferIndexLookup = new Uint8Array(this.MAX_TEMP_BUFFER_SIZE+1);
-      var last = -1, curr = -1;
-      for (var i = 0; i <= this.MAX_TEMP_BUFFER_SIZE; i++) {
-        var size = ceilPower2(i);
-        if (size != last) {
-          curr++;
-          last = size;
-        }
-        this.tempBufferIndexLookup[i] = curr;
-      }
       this.tempVertexBuffers = [];
       this.tempIndexBuffers = [];
-      last = -1;
+      var last = -1, curr = -1;
+      var size = 1;
       for (var i = 0; i <= this.MAX_TEMP_BUFFER_SIZE; i++) {
-        var size = ceilPower2(i);
-        curr = this.tempBufferIndexLookup[i];
+        if (i > size) {
+          size <<= 1;
+        }
         if (size != last) {
+          curr++;
           this.tempVertexBuffers[curr] = Module.ctx.createBuffer();
           Module.ctx.bindBuffer(Module.ctx.ARRAY_BUFFER, this.tempVertexBuffers[curr]);
           Module.ctx.bufferData(Module.ctx.ARRAY_BUFFER, size, Module.ctx.DYNAMIC_DRAW);
@@ -1469,8 +1460,8 @@ var LibraryGL = {
           Module.ctx.bindBuffer(Module.ctx.ELEMENT_ARRAY_BUFFER, null);
           last = size;
         }
+        this.tempBufferIndexLookup[i] = curr;
       }
-
       // GL_QUAD indexes can be precalculated
       this.tempQuadIndexBuffer = Module.ctx.createBuffer();
       Module.ctx.bindBuffer(Module.ctx.ELEMENT_ARRAY_BUFFER, this.tempQuadIndexBuffer);