fix(package): update twgl.js to version 4.9.1

Closes #352

package.json

@@ -38,7 +38,7 @@
     "jsdoc": "^3.5.5",
     "json": "^9.0.4",
     "scratch-vm": "0.2.0-prerelease.20190207224121",
-    "tap": "^13.1.6",
+    "tap": "^11.0.0",
     "travis-after-all": "^1.4.4",
     "uglifyjs-webpack-plugin": "^1.2.5",
     "webpack": "^4.8.0",
@@ -53,7 +53,7 @@
     "minilog": "3.1.0",
     "raw-loader": "^0.5.1",
     "scratch-storage": "^1.0.0",
-    "scratch-svg-renderer": "0.2.0-prerelease.20190419183947",
-    "twgl.js": "4.4.0"
+    "scratch-svg-renderer": "0.2.0-prerelease.20190304180800",
+    "twgl.js": "4.9.1"
   }
 }

src/Drawable.js

@@ -36,10 +36,8 @@ const getLocalPosition = (drawable, vec) => {
     // localPosition matches that transformation.
     localPosition[0] = 0.5 - (((v0 * m[0]) + (v1 * m[4]) + m[12]) / d);
     localPosition[1] = (((v0 * m[1]) + (v1 * m[5]) + m[13]) / d) + 0.5;
-    // Apply texture effect transform if the localPosition is within the drawable's space.
-    if ((localPosition[0] >= 0 && localPosition[0] < 1) && (localPosition[1] >= 0 && localPosition[1] < 1)) {
-        EffectTransform.transformPoint(drawable, localPosition, localPosition);
-    }
+    // Apply texture effect transform.
+    EffectTransform.transformPoint(drawable, localPosition, localPosition);
     return localPosition;
 };
 

src/PenSkin.js

@@ -154,13 +154,6 @@ class PenSkin extends Skin {
         return true;
     }
 
-    /**
-     * @returns {boolean} true if alpha is premultiplied, false otherwise
-     */
-    get hasPremultipliedAlpha () {
-        return true;
-    }
-
     /**
      * @return {Array<number>} the "native" size, in texels, of this skin. [width, height]
      */
@@ -188,9 +181,8 @@ class PenSkin extends Skin {
     clear () {
         const gl = this._renderer.gl;
         twgl.bindFramebufferInfo(gl, this._framebuffer);
-        
-        /* Reset framebuffer to transparent black */
-        gl.clearColor(0, 0, 0, 0);
+
+        gl.clearColor(1, 1, 1, 0);
         gl.clear(gl.COLOR_BUFFER_BIT);
 
         const ctx = this._canvas.getContext('2d');
@@ -606,7 +598,7 @@ class PenSkin extends Skin {
             this._silhouetteBuffer = twgl.createFramebufferInfo(gl, [{format: gl.RGBA}], width, height);
         }
 
-        gl.clearColor(0, 0, 0, 0);
+        gl.clearColor(1, 1, 1, 0);
         gl.clear(gl.COLOR_BUFFER_BIT);
 
         this._silhouetteDirty = true;

src/RenderWebGL.js

@@ -1620,14 +1620,7 @@ class RenderWebGL extends EventEmitter {
             }
 
             twgl.setUniforms(currentShader, uniforms);
-            
-            /* adjust blend function for this skin */
-            if (drawable.skin.hasPremultipliedAlpha){
-                gl.blendFuncSeparate(gl.ONE, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
-            } else {
-                gl.blendFuncSeparate(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
-            }
-            
+
             twgl.drawBufferInfo(gl, this._bufferInfo, gl.TRIANGLES);
         }
 

src/Skin.js

@@ -76,13 +76,6 @@ class Skin extends EventEmitter {
         return false;
     }
 
-    /**
-     * @returns {boolean} true if alpha is premultiplied, false otherwise
-     */
-    get hasPremultipliedAlpha () {
-        return false;
-    }
-
     /**
      * @return {int} the unique ID for this Skin.
      */

src/shaders/sprite.frag

@@ -194,6 +194,12 @@ void main()
 		discard;
 	}
 	#endif // DRAW_MODE_colorMask
+
+	// WebGL defaults to premultiplied alpha
+	#ifndef DRAW_MODE_stamp
+	gl_FragColor.rgb *= gl_FragColor.a;
+	#endif // DRAW_MODE_stamp
+
 	#endif // DRAW_MODE_silhouette
 
 	#else // DRAW_MODE_lineSample