Added inverted alpha to bitmap mask

Author: bitnenfer

src/display/mask/BitmapMask.js

@@ -89,7 +89,7 @@ var BitmapMask = new Class({
          * [description]
          *
          * @name Phaser.Display.Masks.BitmapMask#mainFramebuffer
-         * @type {[type]}
+         * @type {WebGLFramebuffer}
          * @since 3.0.0
          */
         this.mainFramebuffer = null;
@@ -98,11 +98,20 @@ var BitmapMask = new Class({
          * [description]
          *
          * @name Phaser.Display.Masks.BitmapMask#maskFramebuffer
-         * @type {[type]}
+         * @type {WebGLFramebuffer}
          * @since 3.0.0
          */
         this.maskFramebuffer = null;
 
+        /**
+         * [description]
+         *
+         * @name Phaser.Display.Masks.BitmapMask#invertAlpha
+         * @type {boolean}
+         * @since 3.1.2
+         */
+        this.invertAlpha = false;
+
         if (renderer.gl)
         {
             var width = renderer.width;

src/gameobjects/rendertexture/RenderTextureWebGL.js

@@ -1,7 +1,16 @@
 var RenderTextureWebGL = {
 
-    fill: function (color)
+    fill: function (rgb)
     {
+        var ur = ((rgb >> 16)|0) & 0xff;
+        var ug = ((rgb >> 8)|0) & 0xff;
+        var ub = (rgb|0) & 0xff;
+
+        this.renderer.setFramebuffer(this.framebuffer);
+        var gl = this.gl;
+        gl.clearColor(ur / 255.0, ug / 255.0, ub / 255.0, 1);
+        gl.clear(gl.COLOR_BUFFER_BIT);
+        this.renderer.setFramebuffer(null);
         return this;
     },
 

src/renderer/webgl/pipelines/BitmapMaskPipeline.js

@@ -194,7 +194,8 @@ var BitmapMaskPipeline = new Class({
 
             renderer.setTexture2D(mask.maskTexture, 1);
             renderer.setTexture2D(mask.mainTexture, 0);
-            
+            renderer.setInt1(this.program, 'uInvertMaskAlpha', mask.invertAlpha);
+
             // Finally draw a triangle filling the whole screen
             gl.drawArrays(this.topology, 0, 3);
         }

src/renderer/webgl/shaders/BitmapMask.frag

@@ -5,12 +5,23 @@ precision mediump float;
 uniform vec2 uResolution;
 uniform sampler2D uMainSampler;
 uniform sampler2D uMaskSampler;
+uniform bool uInvertMaskAlpha;
 
 void main()
 {
     vec2 uv = gl_FragCoord.xy / uResolution;
     vec4 mainColor = texture2D(uMainSampler, uv);
     vec4 maskColor = texture2D(uMaskSampler, uv);
-    float alpha = maskColor.a * mainColor.a;
+    float alpha = mainColor.a;
+
+    if (!uInvertMaskAlpha)
+    {
+        alpha *= (maskColor.a);
+    }
+    else
+    {
+        alpha *= (1.0 - maskColor.a);
+    }
+    
     gl_FragColor = vec4(mainColor.rgb * alpha, alpha);
 }