Use the tilemap layer alpha value when batch rendering tiles.

Author: pjbaron

src/pixi/extras/Tilemap.js

@@ -284,6 +284,7 @@ PIXI.Tilemap.prototype._renderWholeTilemap = function(renderSession)
   // set the base offset (in screen units) (it's zero, scrolling is now handled by the batch buffer values)
   gl.uniform2f( shader.uScrollOffset, 0, 0 );
   //gl.uniform2f( shader.uScrollOffset, this.scrollX * iWide, -this.scrollY * iHigh );
+  gl.uniform1f( shader.uAlpha, this.alpha );
 
 
   // check if a texture is dirty..

src/pixi/renderers/webgl/shaders/TilemapShader.js

@@ -32,9 +32,12 @@ PIXI.TilemapShader = function(gl)
     this.fragmentSrc = [
         "  precision lowp float;",
         "  uniform sampler2D uImageSampler;",
+        "  uniform float uAlpha;",
         "  varying vec2 vTexCoord;",
         "  void main(void) {",
-        "    gl_FragColor = texture2D(uImageSampler, vTexCoord);",
+        "    vec4 col = texture2D(uImageSampler, vTexCoord);",
+        "    col.a = uAlpha;",
+        "    gl_FragColor = col;",
         "  }"
         ];
 
@@ -79,9 +82,10 @@ PIXI.TilemapShader.prototype.init = function()
     this.aPosition = gl.getAttribLocation(program, 'aPosition');
     this.uSampler = gl.getUniformLocation(program, 'uImageSampler');
     this.uScrollOffset = gl.getUniformLocation(program, 'uScrollOffset');
+    this.uAlpha = gl.getUniformLocation(program, 'uAlpha');
 
     this.attributes = [this.aPosition, this.uSampler];
-    this.uniforms = [this.uScrollOffset];
+    this.uniforms = [this.uScrollOffset, this.uAlpha];
 
     this.program = program;
 };