Added ERASE blend mode.

Author: photonstorm

src/renderer/BlendModes.js

@@ -140,6 +140,13 @@ module.exports = {
      * 
      * @name Phaser.BlendModes.LUMINOSITY
      */
-    LUMINOSITY: 16
+    LUMINOSITY: 16,
+
+    /**
+     * Alpha erase blend mode.
+     * 
+     * @name Phaser.BlendModes.ERASE
+     */
+    ERASE: 17
 
 };

src/renderer/webgl/WebGLRenderer.js

@@ -505,14 +505,15 @@ var WebGLRenderer = new Class({
         //  Set it back into the Game, so developers can access it from there too
         this.game.context = gl;
 
-        for (var i = 0; i <= 16; i++)
+        for (var i = 0; i <= 17; i++)
         {
             this.blendModes.push({ func: [ gl.ONE, gl.ONE_MINUS_SRC_ALPHA ], equation: gl.FUNC_ADD });
         }
 
         this.blendModes[1].func = [ gl.ONE, gl.DST_ALPHA ];
         this.blendModes[2].func = [ gl.DST_COLOR, gl.ONE_MINUS_SRC_ALPHA ];
         this.blendModes[3].func = [ gl.ONE, gl.ONE_MINUS_SRC_COLOR ];
+        this.blendModes[17].func = [ gl.ZERO, gl.ONE_MINUS_SRC_ALPHA ];
 
         this.glFormats[0] = gl.BYTE;
         this.glFormats[1] = gl.SHORT;
@@ -1092,7 +1093,7 @@ var WebGLRenderer = new Class({
      */
     removeBlendMode: function (index)
     {
-        if (index > 16 && this.blendModes[index])
+        if (index > 17 && this.blendModes[index])
         {
             this.blendModes.splice(index, 1);
         }