chore(package): update tap to version 14.9.2

Closes #289

package.json

@@ -37,8 +37,8 @@
     "gh-pages": "^1.0.0",
     "jsdoc": "^3.5.5",
     "json": "^9.0.4",
-    "scratch-vm": "0.2.0-prerelease.20191227164934",
-    "tap": "^11.0.0",
+    "scratch-vm": "0.2.0-prerelease.20190213162739",
+    "tap": "^14.9.2",
     "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.20200205003400",
+    "scratch-svg-renderer": "0.2.0-prerelease.20191104164753",
     "twgl.js": "4.4.0"
   }
 }

src/BitmapSkin.js

@@ -18,6 +18,9 @@ class BitmapSkin extends Skin {
         /** @type {!RenderWebGL} */
         this._renderer = renderer;
 
+        /** @type {WebGLTexture} */
+        this._texture = null;
+
         /** @type {Array<int>} */
         this._textureSize = [0, 0];
     }
@@ -92,17 +95,22 @@ class BitmapSkin extends Skin {
             textureData = context.getImageData(0, 0, bitmapData.width, bitmapData.height);
         }
 
-        if (this._texture === null) {
+        if (this._texture) {
+            gl.bindTexture(gl.TEXTURE_2D, this._texture);
+            gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textureData);
+            this._silhouette.update(textureData);
+        } else {
+            // TODO: mipmaps?
             const textureOptions = {
-                auto: false,
-                wrap: gl.CLAMP_TO_EDGE
+                auto: true,
+                wrap: gl.CLAMP_TO_EDGE,
+                src: textureData
             };
 
             this._texture = twgl.createTexture(gl, textureOptions);
+            this._silhouette.update(textureData);
         }
 
-        this._setTexture(textureData);
-
         // Do these last in case any of the above throws an exception
         this._costumeResolution = costumeResolution || 2;
         this._textureSize = BitmapSkin._getBitmapSize(bitmapData);

src/Drawable.js

@@ -36,12 +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,
-    // and any effects are currently active.
-    if (drawable.enabledEffects !== 0 &&
-        (localPosition[0] >= 0 && localPosition[0] < 1) &&
-        (localPosition[1] >= 0 && localPosition[1] < 1)) {
-
+    // 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);
     }
     return localPosition;
@@ -100,11 +96,7 @@ class Drawable {
         this._inverseMatrix = twgl.m4.identity();
         this._inverseTransformDirty = true;
         this._visible = true;
-
-        /** A bitmask identifying which effects are currently in use.
-         * @readonly
-         * @type {int} */
-        this.enabledEffects = 0;
+        this._effectBits = 0;
 
         /** @todo move convex hull functionality, maybe bounds functionality overall, to Skin classes */
         this._convexHullPoints = null;
@@ -167,6 +159,13 @@ class Drawable {
         return [this._scale[0], this._scale[1]];
     }
 
+    /**
+     * @returns {int} A bitmask identifying which effects are currently in use.
+     */
+    getEnabledEffects () {
+        return this._effectBits;
+    }
+
     /**
      * @returns {object.<string, *>} the shader uniforms to be used when rendering this Drawable.
      */
@@ -243,9 +242,9 @@ class Drawable {
     updateEffect (effectName, rawValue) {
         const effectInfo = ShaderManager.EFFECT_INFO[effectName];
         if (rawValue) {
-            this.enabledEffects |= effectInfo.mask;
+            this._effectBits |= effectInfo.mask;
         } else {
-            this.enabledEffects &= ~effectInfo.mask;
+            this._effectBits &= ~effectInfo.mask;
         }
         const converter = effectInfo.converter;
         this._uniforms[effectInfo.uniformName] = converter(rawValue);
@@ -482,7 +481,7 @@ class Drawable {
         }
 
         // If the effect bits for mosaic, pixelate, whirl, or fisheye are set, use linear
-        if ((this.enabledEffects & (
+        if ((this._effectBits & (
             ShaderManager.EFFECT_INFO.fisheye.mask |
             ShaderManager.EFFECT_INFO.whirl.mask |
             ShaderManager.EFFECT_INFO.pixelate.mask |
@@ -685,9 +684,6 @@ class Drawable {
         const localPosition = getLocalPosition(drawable, vec);
         if (localPosition[0] < 0 || localPosition[1] < 0 ||
             localPosition[0] > 1 || localPosition[1] > 1) {
-            dst[0] = 0;
-            dst[1] = 0;
-            dst[2] = 0;
             dst[3] = 0;
             return dst;
         }
@@ -696,9 +692,7 @@ class Drawable {
         // drawable.useNearest() ?
              drawable.skin._silhouette.colorAtNearest(localPosition, dst);
         // : drawable.skin._silhouette.colorAtLinear(localPosition, dst);
-
-        if (drawable.enabledEffects === 0) return textColor;
-        return EffectTransform.transformColor(drawable, textColor);
+        return EffectTransform.transformColor(drawable, textColor, textColor);
     }
 }
 

src/EffectTransform.js

@@ -114,39 +114,36 @@ const hslToRgb = ([h, s, l]) => {
 class EffectTransform {
 
     /**
-     * Transform a color in-place given the drawable's effect uniforms.  Will apply
+     * Transform a color given the drawables effect uniforms.  Will apply
      * Ghost and Color and Brightness effects.
      * @param {Drawable} drawable The drawable to get uniforms from.
-     * @param {Uint8ClampedArray} inOutColor The color to transform.
+     * @param {Uint8ClampedArray} color4b The initial color.
+     * @param {Uint8ClampedArary} [dst] Working space to save the color in (is returned)
+     * @param {number} [effectMask] A bitmask for which effects to use. Optional.
      * @returns {Uint8ClampedArray} dst filled with the transformed color
      */
-    static transformColor (drawable, inOutColor) {
-
-        // If the color is fully transparent, don't bother attempting any transformations.
-        if (inOutColor[3] === 0) {
-            return inOutColor;
+    static transformColor (drawable, color4b, dst, effectMask) {
+        dst = dst || new Uint8ClampedArray(4);
+        effectMask = effectMask || 0xffffffff;
+        dst.set(color4b);
+        if (dst[3] === 0) {
+            return dst;
         }
 
-        const effects = drawable.enabledEffects;
         const uniforms = drawable.getUniforms();
+        const effects = drawable.getEnabledEffects() & effectMask;
+
+        if ((effects & ShaderManager.EFFECT_INFO.ghost.mask) !== 0) {
+            // gl_FragColor.a *= u_ghost
+            dst[3] *= uniforms.u_ghost;
+        }
 
         const enableColor = (effects & ShaderManager.EFFECT_INFO.color.mask) !== 0;
         const enableBrightness = (effects & ShaderManager.EFFECT_INFO.brightness.mask) !== 0;
 
         if (enableColor || enableBrightness) {
-            // gl_FragColor.rgb /= gl_FragColor.a + epsilon;
-            // Here, we're dividing by the (previously pre-multiplied) alpha to ensure HSV is properly calculated
-            // for partially transparent pixels.
-            // epsilon is present in the shader because dividing by 0 (fully transparent pixels) messes up calculations.
-            // We're doing this with a Uint8ClampedArray here, so dividing by 0 just gives 255. We're later multiplying
-            // by 0 again, so it won't affect results.
-            const alpha = inOutColor[3] / 255;
-            inOutColor[0] /= alpha;
-            inOutColor[1] /= alpha;
-            inOutColor[2] /= alpha;
-
             // vec3 hsl = convertRGB2HSL(gl_FragColor.xyz);
-            const hsl = rgbToHsl(inOutColor);
+            const hsl = rgbToHsl(dst);
 
             if (enableColor) {
                 // this code forces grayscale values to be slightly saturated
@@ -176,38 +173,25 @@ class EffectTransform {
                 hsl[2] = Math.min(1, hsl[2] + uniforms.u_brightness);
             }
             // gl_FragColor.rgb = convertHSL2RGB(hsl);
-            inOutColor.set(hslToRgb(hsl));
-
-            // gl_FragColor.rgb *= gl_FragColor.a + epsilon;
-            // Now we're doing the reverse, premultiplying by the alpha once again.
-            inOutColor[0] *= alpha;
-            inOutColor[1] *= alpha;
-            inOutColor[2] *= alpha;
+            dst.set(hslToRgb(hsl));
         }
 
-        if ((effects & ShaderManager.EFFECT_INFO.ghost.mask) !== 0) {
-            // gl_FragColor *= u_ghost
-            inOutColor[0] *= uniforms.u_ghost;
-            inOutColor[1] *= uniforms.u_ghost;
-            inOutColor[2] *= uniforms.u_ghost;
-            inOutColor[3] *= uniforms.u_ghost;
-        }
-
-        return inOutColor;
+        return dst;
     }
 
     /**
      * Transform a texture coordinate to one that would be select after applying shader effects.
      * @param {Drawable} drawable The drawable whose effects to emulate.
      * @param {twgl.v3} vec The texture coordinate to transform.
-     * @param {twgl.v3} dst A place to store the output coordinate.
+     * @param {?twgl.v3} dst A place to store the output coordinate.
      * @return {twgl.v3} dst - The coordinate after being transform by effects.
      */
-    static transformPoint (drawable, vec, dst) {
+    static transformPoint (drawable, vec, dst = twgl.v3.create()) {
         twgl.v3.copy(vec, dst);
 
-        const effects = drawable.enabledEffects;
         const uniforms = drawable.getUniforms();
+        const effects = drawable.getEnabledEffects();
+
         if ((effects & ShaderManager.EFFECT_INFO.mosaic.mask) !== 0) {
             // texcoord0 = fract(u_mosaic * texcoord0);
             dst[0] = uniforms.u_mosaic * dst[0] % 1;

src/PenSkin.js

@@ -25,12 +25,6 @@ const DefaultPenAttributes = {
     diameter: 1
 };
 
-/**
- * Reused memory location for storing a premultiplied pen color.
- * @type {FloatArray}
- */
-const __premultipliedColor = [0, 0, 0, 0];
-
 
 /**
  * Reused memory location for projection matrices.
@@ -44,6 +38,11 @@ const __projectionMatrix = twgl.m4.identity();
  */
 const __modelTranslationMatrix = twgl.m4.identity();
 
+/**
+ * Reused memory location for rotation matrix for building a model matrix.
+ * @type {FloatArray}
+ */
+const __modelRotationMatrix = twgl.m4.identity();
 
 /**
  * Reused memory location for scaling matrix for building a model matrix.
@@ -89,6 +88,9 @@ class PenSkin extends Skin {
         /** @type {HTMLCanvasElement} */
         this._canvas = document.createElement('canvas');
 
+        /** @type {WebGLTexture} */
+        this._texture = null;
+
         /** @type {WebGLTexture} */
         this._exportTexture = null;
 
@@ -104,12 +106,6 @@ class PenSkin extends Skin {
         /** @type {boolean} */
         this._silhouetteDirty = false;
 
-        /** @type {Uint8Array} */
-        this._silhouettePixels = null;
-
-        /** @type {ImageData} */
-        this._silhouetteImageData = null;
-
         /** @type {object} */
         this._lineOnBufferDrawRegionId = {
             enter: () => this._enterDrawLineOnBuffer(),
@@ -127,10 +123,10 @@ class PenSkin extends Skin {
 
         const NO_EFFECTS = 0;
         /** @type {twgl.ProgramInfo} */
-        this._stampShader = this._renderer._shaderManager.getShader(ShaderManager.DRAW_MODE.default, NO_EFFECTS);
+        this._stampShader = this._renderer._shaderManager.getShader(ShaderManager.DRAW_MODE.stamp, NO_EFFECTS);
 
         /** @type {twgl.ProgramInfo} */
-        this._lineShader = this._renderer._shaderManager.getShader(ShaderManager.DRAW_MODE.line, NO_EFFECTS);
+        this._lineShader = this._renderer._shaderManager.getShader(ShaderManager.DRAW_MODE.lineSample, NO_EFFECTS);
 
         this._createLineGeometry();
 
@@ -158,6 +154,13 @@ 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]
      */
@@ -185,7 +188,7 @@ 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.clear(gl.COLOR_BUFFER_BIT);
@@ -216,15 +219,10 @@ class PenSkin extends Skin {
      * @param {number} y1 - the Y coordinate of the end of the line.
      */
     drawLine (penAttributes, x0, y0, x1, y1) {
-        // For compatibility with Scratch 2.0, offset pen lines of width 1 and 3 so they're pixel-aligned.
-        // See https://github.com/LLK/scratch-render/pull/314
-        const diameter = penAttributes.diameter || DefaultPenAttributes.diameter;
-        const offset = (diameter === 1 || diameter === 3) ? 0.5 : 0;
-
         this._drawLineOnBuffer(
             penAttributes,
-            x0 + offset, y0 + offset,
-            x1 + offset, y1 + offset
+            this._rotationCenter[0] + x0, this._rotationCenter[1] - y0,
+            this._rotationCenter[0] + x1, this._rotationCenter[1] - y1
         );
 
         this._silhouetteDirty = true;
@@ -234,16 +232,72 @@ class PenSkin extends Skin {
      * Create 2D geometry for drawing lines to a framebuffer.
      */
     _createLineGeometry () {
+        // Create a set of triangulated quads that break up a line into 3 parts:
+        // 2 caps and a body. The y component of these position vertices are
+        // divided to bring a value of 1 down to 0.5 to 0. The large y values
+        // are set so they will still be at least 0.5 after division. The
+        // divisor is scaled based on the length of the line and the lines
+        // width.
+        //
+        // Texture coordinates are based on a "generated" texture whose general
+        // shape is a circle. The line caps set their texture values to define
+        // there roundedness with the texture. The body has all of its texture
+        // values set to the center of the texture so it's a solid block.
         const quads = {
             a_position: {
                 numComponents: 2,
                 data: [
+                    -0.5, 1,
+                    0.5, 1,
+                    -0.5, 100000,
+
+                    -0.5, 100000,
+                    0.5, 1,
+                    0.5, 100000,
+
+                    -0.5, 1,
+                    0.5, 1,
+                    -0.5, -1,
+
+                    -0.5, -1,
+                    0.5, 1,
+                    0.5, -1,
+
+                    -0.5, -100000,
+                    0.5, -100000,
+                    -0.5, -1,
+
+                    -0.5, -1,
+                    0.5, -100000,
+                    0.5, -1
+                ]
+            },
+            a_texCoord: {
+                numComponents: 2,
+                data: [
+                    1, 0.5,
+                    0, 0.5,
+                    1, 0,
+
+                    1, 0,
+                    0, 0.5,
+                    0, 0,
+
+                    0.5, 0,
+                    0.5, 1,
+                    0.5, 0,
+
+                    0.5, 0,
+                    0.5, 1,
+                    0.5, 1,
+
                     1, 0,
                     0, 0,
-                    1, 1,
-                    1, 1,
+                    1, 0.5,
+
+                    1, 0.5,
                     0, 0,
-                    0, 1
+                    0, 0.5
                 ]
             }
         };
@@ -263,6 +317,13 @@ class PenSkin extends Skin {
 
         twgl.bindFramebufferInfo(gl, this._framebuffer);
 
+        // Needs a blend function that blends a destination that starts with
+        // no alpha.
+        gl.blendFuncSeparate(
+            gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA,
+            gl.ONE, gl.ONE_MINUS_SRC_ALPHA
+        );
+
         gl.viewport(0, 0, bounds.width, bounds.height);
 
         gl.useProgram(currentShader.program);
@@ -283,13 +344,13 @@ class PenSkin extends Skin {
     _exitDrawLineOnBuffer () {
         const gl = this._renderer.gl;
 
+        gl.blendFuncSeparate(gl.ONE, gl.ONE_MINUS_SRC_ALPHA, gl.ZERO, gl.ONE);
+
         twgl.bindFramebufferInfo(gl, null);
     }
 
     /**
      * Draw a line on the framebuffer.
-     * Note that the point coordinates are in the following coordinate space:
-     * +y is down, (0, 0) is the center, and the coords range from (-width / 2, -height / 2) to (height / 2, width / 2).
      * @param {PenAttributes} penAttributes - how the line should be drawn.
      * @param {number} x0 - the X coordinate of the beginning of the line.
      * @param {number} y0 - the Y coordinate of the beginning of the line.
@@ -303,18 +364,40 @@ class PenSkin extends Skin {
 
         this._renderer.enterDrawRegion(this._lineOnBufferDrawRegionId);
 
-        // Premultiply pen color by pen transparency
-        const penColor = penAttributes.color4f || DefaultPenAttributes.color4f;
-        __premultipliedColor[0] = penColor[0] * penColor[3];
-        __premultipliedColor[1] = penColor[1] * penColor[3];
-        __premultipliedColor[2] = penColor[2] * penColor[3];
-        __premultipliedColor[3] = penColor[3];
+        const diameter = penAttributes.diameter || DefaultPenAttributes.diameter;
+        const length = Math.hypot(Math.abs(x1 - x0) - 0.001, Math.abs(y1 - y0) - 0.001);
+        const avgX = (x0 + x1) / 2;
+        const avgY = (y0 + y1) / 2;
+        const theta = Math.atan2(y0 - y1, x0 - x1);
+        const alias = 1;
+
+        // The line needs a bit of aliasing to look smooth. Add a small offset
+        // and a small size boost to scaling to give a section to alias.
+        const translationVector = __modelTranslationVector;
+        translationVector[0] = avgX - (alias / 2);
+        translationVector[1] = avgY + (alias / 4);
+
+        const scalingVector = __modelScalingVector;
+        scalingVector[0] = diameter + alias;
+        scalingVector[1] = length + diameter - (alias / 2);
+
+        const radius = diameter / 2;
+        const yScalar = (0.50001 - (radius / (length + diameter)));
 
         const uniforms = {
-            u_lineColor: __premultipliedColor,
-            u_lineThickness: penAttributes.diameter || DefaultPenAttributes.diameter,
-            u_penPoints: [x0, -y0, x1, -y1],
-            u_stageSize: this.size
+            u_positionScalar: yScalar,
+            u_capScale: diameter,
+            u_aliasAmount: alias,
+            u_modelMatrix: twgl.m4.multiply(
+                twgl.m4.multiply(
+                    twgl.m4.translation(translationVector, __modelTranslationMatrix),
+                    twgl.m4.rotationZ(theta - (Math.PI / 2), __modelRotationMatrix),
+                    __modelMatrix
+                ),
+                twgl.m4.scaling(scalingVector, __modelScalingMatrix),
+                __modelMatrix
+            ),
+            u_lineColor: penAttributes.color4f || DefaultPenAttributes.color4f
         };
 
         twgl.setUniforms(currentShader, uniforms);
@@ -407,6 +490,8 @@ class PenSkin extends Skin {
 
         twgl.bindFramebufferInfo(gl, this._framebuffer);
 
+        gl.blendFuncSeparate(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
+
         this._drawRectangleRegionEnter(this._stampShader, this._bounds);
     }
 
@@ -416,6 +501,8 @@ class PenSkin extends Skin {
     _exitDrawToBuffer () {
         const gl = this._renderer.gl;
 
+        gl.blendFuncSeparate(gl.ONE, gl.ONE_MINUS_SRC_ALPHA, gl.ZERO, gl.ONE);
+
         twgl.bindFramebufferInfo(gl, null);
     }
 
@@ -520,9 +607,6 @@ class PenSkin extends Skin {
         gl.clearColor(0, 0, 0, 0);
         gl.clear(gl.COLOR_BUFFER_BIT);
 
-        this._silhouettePixels = new Uint8Array(Math.floor(width * height * 4));
-        this._silhouetteImageData = this._canvas.getContext('2d').createImageData(width, height);
-
         this._silhouetteDirty = true;
     }
 
@@ -560,17 +644,24 @@ class PenSkin extends Skin {
             // Render export texture to another framebuffer
             const gl = this._renderer.gl;
 
+            const bounds = this._bounds;
+
             this._renderer.enterDrawRegion(this._toBufferDrawRegionId);
 
             // Sample the framebuffer's pixels into the silhouette instance
-            gl.readPixels(
-                0, 0,
-                this._canvas.width, this._canvas.height,
-                gl.RGBA, gl.UNSIGNED_BYTE, this._silhouettePixels
-            );
+            const skinPixels = new Uint8Array(Math.floor(this._canvas.width * this._canvas.height * 4));
+            gl.readPixels(0, 0, this._canvas.width, this._canvas.height, gl.RGBA, gl.UNSIGNED_BYTE, skinPixels);
 
-            this._silhouetteImageData.data.set(this._silhouettePixels);
-            this._silhouette.update(this._silhouetteImageData, true /* isPremultiplied */);
+            const skinCanvas = this._canvas;
+            skinCanvas.width = bounds.width;
+            skinCanvas.height = bounds.height;
+
+            const skinContext = skinCanvas.getContext('2d');
+            const skinImageData = skinContext.createImageData(bounds.width, bounds.height);
+            skinImageData.data.set(skinPixels);
+            skinContext.putImageData(skinImageData, 0, 0);
+
+            this._silhouette.update(this._canvas);
 
             this._silhouetteDirty = false;
         }

src/RenderWebGL.js

@@ -196,7 +196,7 @@ class RenderWebGL extends EventEmitter {
         gl.disable(gl.DEPTH_TEST);
         /** @todo disable when no partial transparency? */
         gl.enable(gl.BLEND);
-        gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
+        gl.blendFuncSeparate(gl.ONE, gl.ONE_MINUS_SRC_ALPHA, gl.ZERO, gl.ONE);
     }
 
     /**
@@ -220,20 +220,9 @@ class RenderWebGL extends EventEmitter {
      * @param {int} pixelsTall The desired height in device-independent pixels.
      */
     resize (pixelsWide, pixelsTall) {
-        const {canvas} = this._gl;
         const pixelRatio = window.devicePixelRatio || 1;
-        const newWidth = pixelsWide * pixelRatio;
-        const newHeight = pixelsTall * pixelRatio;
-
-        // Certain operations, such as moving the color picker, call `resize` once per frame, even though the canvas
-        // size doesn't change. To avoid unnecessary canvas updates, check that we *really* need to resize the canvas.
-        if (canvas.width !== newWidth || canvas.height !== newHeight) {
-            canvas.width = newWidth;
-            canvas.height = newHeight;
-            // Resizing the canvas causes it to be cleared, so redraw it.
-            this.draw();
-        }
-
+        this._gl.canvas.width = pixelsWide * pixelRatio;
+        this._gl.canvas.height = pixelsTall * pixelRatio;
     }
 
     /**
@@ -845,8 +834,7 @@ class RenderWebGL extends EventEmitter {
                 projection,
                 {
                     extraUniforms,
-                    ignoreVisibility: true, // Touching color ignores sprite visibility,
-                    effectMask: ~ShaderManager.EFFECT_INFO.ghost.mask
+                    ignoreVisibility: true // Touching color ignores sprite visibility
                 });
 
             gl.stencilFunc(gl.EQUAL, 1, 1);
@@ -984,7 +972,7 @@ class RenderWebGL extends EventEmitter {
 
         drawable.updateMatrix();
         if (drawable.skin) {
-            drawable.skin.updateSilhouette(this._getDrawableScreenSpaceScale(drawable));
+            drawable.skin.updateSilhouette();
         } else {
             log.warn(`Could not find skin for drawable with id: ${drawableID}`);
         }
@@ -1020,7 +1008,7 @@ class RenderWebGL extends EventEmitter {
             if (drawable.getVisible() && drawable.getUniforms().u_ghost !== 0) {
                 drawable.updateMatrix();
                 if (drawable.skin) {
-                    drawable.skin.updateSilhouette(this._getDrawableScreenSpaceScale(drawable));
+                    drawable.skin.updateSilhouette();
                 } else {
                     log.warn(`Could not find skin for drawable with id: ${id}`);
                 }
@@ -1135,8 +1123,7 @@ class RenderWebGL extends EventEmitter {
         gl.clear(gl.COLOR_BUFFER_BIT);
         try {
             gl.disable(gl.BLEND);
-            // ImageData objects store alpha un-premultiplied, so draw with the `straightAlpha` draw mode.
-            this._drawThese([drawableID], ShaderManager.DRAW_MODE.straightAlpha, projection,
+            this._drawThese([drawableID], ShaderManager.DRAW_MODE.default, projection,
                 {effectMask: ~ShaderManager.EFFECT_INFO.ghost.mask});
         } finally {
             gl.enable(gl.BLEND);
@@ -1256,7 +1243,7 @@ class RenderWebGL extends EventEmitter {
         if (!drawable.skin || !drawable.skin.getTexture([100, 100])) return null;
 
         drawable.updateMatrix();
-        drawable.skin.updateSilhouette(this._getDrawableScreenSpaceScale(drawable));
+        drawable.skin.updateSilhouette();
         const bounds = drawable.getFastBounds();
 
         // Limit queries to the stage size.
@@ -1294,7 +1281,7 @@ class RenderWebGL extends EventEmitter {
                 if (drawable.skin && drawable._visible) {
                     // Update the CPU position data
                     drawable.updateMatrix();
-                    drawable.skin.updateSilhouette(this._getDrawableScreenSpaceScale(drawable));
+                    drawable.skin.updateSilhouette();
                     const candidateBounds = drawable.getFastBounds();
                     if (bounds.intersects(candidateBounds)) {
                         result.push({
@@ -1555,20 +1542,23 @@ class RenderWebGL extends EventEmitter {
         const skin = /** @type {PenSkin} */ this._allSkins[penSkinID];
 
         const gl = this._gl;
-        twgl.bindFramebufferInfo(gl, skin._framebuffer);
+        twgl.bindFramebufferInfo(gl, this._queryBufferInfo);
 
         // Limit size of viewport to the bounds around the stamp Drawable and create the projection matrix for the draw.
-        gl.viewport(
-            (this._nativeSize[0] * 0.5) + bounds.left,
-            (this._nativeSize[1] * 0.5) - bounds.top,
-            bounds.width,
-            bounds.height
-        );
+        gl.viewport(0, 0, bounds.width, bounds.height);
         const projection = twgl.m4.ortho(bounds.left, bounds.right, bounds.top, bounds.bottom, -1, 1);
 
-        // Draw the stamped sprite onto the PenSkin's framebuffer.
-        this._drawThese([stampID], ShaderManager.DRAW_MODE.default, projection, {ignoreVisibility: true});
-        skin._silhouetteDirty = true;
+        gl.clearColor(0, 0, 0, 0);
+        gl.clear(gl.COLOR_BUFFER_BIT);
+
+        try {
+            gl.disable(gl.BLEND);
+            this._drawThese([stampID], ShaderManager.DRAW_MODE.stamp, projection, {ignoreVisibility: true});
+        } finally {
+            gl.enable(gl.BLEND);
+        }
+
+        skin._drawToBuffer(this._queryBufferInfo.attachments[0], bounds.left, bounds.top);
     }
 
     /* ******
@@ -1672,18 +1662,6 @@ class RenderWebGL extends EventEmitter {
         this._regionId = null;
     }
 
-    /**
-     * Get the screen-space scale of a drawable, as percentages of the drawable's "normal" size.
-     * @param {Drawable} drawable The drawable whose screen-space scale we're fetching.
-     * @returns {Array<number>} The screen-space X and Y dimensions of the drawable's scale, as percentages.
-     */
-    _getDrawableScreenSpaceScale (drawable) {
-        return [
-            drawable.scale[0] * this._gl.canvas.width / this._nativeSize[0],
-            drawable.scale[1] * this._gl.canvas.height / this._nativeSize[1]
-        ];
-    }
-
     /**
      * Draw a set of Drawables, by drawable ID
      * @param {Array<int>} drawables The Drawable IDs to draw, possibly this._drawList.
@@ -1716,14 +1694,17 @@ class RenderWebGL extends EventEmitter {
             if (!drawable.getVisible() && !opts.ignoreVisibility) continue;
 
             // Combine drawable scale with the native vs. backing pixel ratio
-            const drawableScale = this._getDrawableScreenSpaceScale(drawable);
+            const drawableScale = [
+                drawable.scale[0] * this._gl.canvas.width / this._nativeSize[0],
+                drawable.scale[1] * this._gl.canvas.height / this._nativeSize[1]
+            ];
 
             // If the skin or texture isn't ready yet, skip it.
             if (!drawable.skin || !drawable.skin.getTexture(drawableScale)) continue;
 
             const uniforms = {};
 
-            let effectBits = drawable.enabledEffects;
+            let effectBits = drawable.getEnabledEffects();
             effectBits &= opts.hasOwnProperty('effectMask') ? opts.effectMask : effectBits;
             const newShader = this._shaderManager.getShader(drawMode, effectBits);
 
@@ -1757,6 +1738,14 @@ 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);
         }
 
@@ -1773,10 +1762,6 @@ class RenderWebGL extends EventEmitter {
      */
     _getConvexHullPointsForDrawable (drawableID) {
         const drawable = this._allDrawables[drawableID];
-
-        drawable.updateMatrix();
-        drawable.skin.updateSilhouette(this._getDrawableScreenSpaceScale(drawable));
-
         const [width, height] = drawable.skin.size;
         // No points in the hull if invisible or size is 0.
         if (!drawable.getVisible() || width === 0 || height === 0) {
@@ -1911,11 +1896,13 @@ class RenderWebGL extends EventEmitter {
             }
             */
             Drawable.sampleColor4b(vec, drawables[index].drawable, __blendColor);
-            // Equivalent to gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA)
-            dst[0] += __blendColor[0] * blendAlpha;
-            dst[1] += __blendColor[1] * blendAlpha;
-            dst[2] += __blendColor[2] * blendAlpha;
-            blendAlpha *= (1 - (__blendColor[3] / 255));
+            // if we are fully transparent, go to the next one "down"
+            const sampleAlpha = __blendColor[3] / 255;
+            // premultiply alpha
+            dst[0] += __blendColor[0] * blendAlpha * sampleAlpha;
+            dst[1] += __blendColor[1] * blendAlpha * sampleAlpha;
+            dst[2] += __blendColor[2] * blendAlpha * sampleAlpha;
+            blendAlpha *= (1 - sampleAlpha);
         }
         // Backdrop could be transparent, so we need to go to the "clear color" of the
         // draw scene (white) as a fallback if everything was alpha

src/SVGSkin.js

@@ -4,14 +4,6 @@ const Skin = require('./Skin');
 const SvgRenderer = require('scratch-svg-renderer').SVGRenderer;
 
 const MAX_TEXTURE_DIMENSION = 2048;
-const MIN_TEXTURE_SCALE = 1 / 256;
-/**
- * All scaled renderings of the SVG are stored in an array. The 1.0 scale of
- * the SVG is stored at the 8th index. The smallest possible 1 / 256 scale
- * rendering is stored at the 0th index.
- * @const {number}
- */
-const INDEX_OFFSET = 8;
 
 class SVGSkin extends Skin {
     /**
@@ -30,24 +22,24 @@ class SVGSkin extends Skin {
         /** @type {SvgRenderer} */
         this._svgRenderer = new SvgRenderer();
 
-        /** @type {Array<WebGLTexture>} */
-        this._scaledMIPs = [];
+        /** @type {WebGLTexture} */
+        this._texture = null;
 
         /** @type {number} */
-        this._largestMIPScale = 0;
+        this._textureScale = 1;
 
-        /**
-        * Ratio of the size of the SVG and the max size of the WebGL texture
-        * @type {Number}
-        */
-        this._maxTextureScale = 1;
+        /** @type {Number} */
+        this._maxTextureScale = 0;
     }
 
     /**
      * Dispose of this object. Do not use it after calling this method.
      */
     dispose () {
-        this.resetMIPs();
+        if (this._texture) {
+            this._renderer.gl.deleteTexture(this._texture);
+            this._texture = null;
+        }
         super.dispose();
     }
 
@@ -68,111 +60,89 @@ class SVGSkin extends Skin {
         super.setRotationCenter(x - viewOffset[0], y - viewOffset[1]);
     }
 
-    /**
-     * Create a MIP for a given scale.
-     * @param {number} scale - The relative size of the MIP
-     * @return {SVGMIP} An object that handles creating and updating SVG textures.
-     */
-    createMIP (scale) {
-        this._svgRenderer.draw(scale);
-
-        // Pull out the ImageData from the canvas. ImageData speeds up
-        // updating Silhouette and is better handled by more browsers in
-        // regards to memory.
-        const canvas = this._svgRenderer.canvas;
-        // If one of the canvas dimensions is 0, set this MIP to an empty image texture.
-        // This avoids an IndexSizeError from attempting to getImageData when one of the dimensions is 0.
-        if (canvas.width === 0 || canvas.height === 0) return super.getTexture();
-
-        const context = canvas.getContext('2d');
-        const textureData = context.getImageData(0, 0, canvas.width, canvas.height);
-
-        const textureOptions = {
-            auto: false,
-            wrap: this._renderer.gl.CLAMP_TO_EDGE,
-            src: textureData,
-            premultiplyAlpha: true
-        };
-
-        const mip = twgl.createTexture(this._renderer.gl, textureOptions);
-
-        // Check if this is the largest MIP created so far. Currently, silhouettes only get scaled up.
-        if (this._largestMIPScale < scale) {
-            this._silhouette.update(textureData);
-            this._largestMIPScale = scale;
-        }
-
-        return mip;
-    }
-
-    updateSilhouette (scale = 1) {
-        // Ensure a silhouette exists.
-        this.getTexture(scale);
-    }
-
     /**
      * @param {Array<number>} scale - The scaling factors to be used, each in the [0,100] range.
      * @return {WebGLTexture} The GL texture representation of this skin when drawing at the given scale.
      */
+    // eslint-disable-next-line no-unused-vars
     getTexture (scale) {
+        if (!this._svgRenderer.canvas.width || !this._svgRenderer.canvas.height) {
+            return super.getTexture();
+        }
+
         // The texture only ever gets uniform scale. Take the larger of the two axes.
         const scaleMax = scale ? Math.max(Math.abs(scale[0]), Math.abs(scale[1])) : 100;
         const requestedScale = Math.min(scaleMax / 100, this._maxTextureScale);
-        let newScale = 1;
-        let textureIndex = 0;
+        let newScale = this._textureScale;
+        while ((newScale < this._maxTextureScale) && (requestedScale >= 1.5 * newScale)) {
+            newScale *= 2;
+        }
+        if (this._textureScale !== newScale) {
+            this._textureScale = newScale;
+            this._svgRenderer._draw(this._textureScale, () => {
+                if (this._textureScale === newScale) {
+                    const canvas = this._svgRenderer.canvas;
+                    const context = canvas.getContext('2d');
+                    const textureData = context.getImageData(0, 0, canvas.width, canvas.height);
 
-        if (requestedScale < 1) {
-            while ((newScale > MIN_TEXTURE_SCALE) && (requestedScale <= newScale * .75)) {
-                newScale /= 2;
-                textureIndex -= 1;
-            }
-        } else {
-            while ((newScale < this._maxTextureScale) && (requestedScale >= 1.5 * newScale)) {
-                newScale *= 2;
-                textureIndex += 1;
-            }
+                    const gl = this._renderer.gl;
+                    gl.bindTexture(gl.TEXTURE_2D, this._texture);
+                    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textureData);
+                    this._silhouette.update(textureData);
+                }
+            });
         }
 
-        if (this._svgRenderer.loaded && !this._scaledMIPs[textureIndex + INDEX_OFFSET]) {
-            this._scaledMIPs[textureIndex + INDEX_OFFSET] = this.createMIP(newScale);
-        }
-
-        return this._scaledMIPs[textureIndex + INDEX_OFFSET] || super.getTexture();
-    }
-
-    /**
-     * Do a hard reset of the existing MIPs by deleting them.
-     * @param {Array<number>} [rotationCenter] - Optional rotation center for the SVG. If not supplied, it will be
-     * calculated from the bounding box
-     * @fires Skin.event:WasAltered
-     */
-    resetMIPs () {
-        this._scaledMIPs.forEach(oldMIP => this._renderer.gl.deleteTexture(oldMIP));
-        this._scaledMIPs.length = 0;
-        this._largestMIPScale = 0;
+        return this._texture;
     }
 
     /**
      * Set the contents of this skin to a snapshot of the provided SVG data.
      * @param {string} svgData - new SVG to use.
-     * @param {Array<number>} [rotationCenter] - Optional rotation center for the SVG.
+     * @param {Array<number>} [rotationCenter] - Optional rotation center for the SVG. If not supplied, it will be
+     * calculated from the bounding box
+     * @fires Skin.event:WasAltered
      */
     setSVG (svgData, rotationCenter) {
-        this._svgRenderer.loadSVG(svgData, false, () => {
-            const svgSize = this._svgRenderer.size;
-            if (svgSize[0] === 0 || svgSize[1] === 0) {
+        this._svgRenderer.fromString(svgData, 1, () => {
+            const gl = this._renderer.gl;
+            this._textureScale = this._maxTextureScale = 1;
+
+            // Pull out the ImageData from the canvas. ImageData speeds up
+            // updating Silhouette and is better handled by more browsers in
+            // regards to memory.
+            const canvas = this._svgRenderer.canvas;
+
+            if (!canvas.width || !canvas.height) {
                 super.setEmptyImageData();
                 return;
             }
 
-            const maxDimension = Math.ceil(Math.max(this.size[0], this.size[1]));
+            const context = canvas.getContext('2d');
+            const textureData = context.getImageData(0, 0, canvas.width, canvas.height);
+
+            if (this._texture) {
+                gl.bindTexture(gl.TEXTURE_2D, this._texture);
+                gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textureData);
+                this._silhouette.update(textureData);
+            } else {
+                // TODO: mipmaps?
+                const textureOptions = {
+                    auto: true,
+                    wrap: gl.CLAMP_TO_EDGE,
+                    src: textureData
+                };
+
+                this._texture = twgl.createTexture(gl, textureOptions);
+                this._silhouette.update(textureData);
+            }
+
+            const maxDimension = Math.max(this._svgRenderer.canvas.width, this._svgRenderer.canvas.height);
             let testScale = 2;
             for (testScale; maxDimension * testScale <= MAX_TEXTURE_DIMENSION; testScale *= 2) {
                 this._maxTextureScale = testScale;
             }
 
-            this.resetMIPs();
-
             if (typeof rotationCenter === 'undefined') rotationCenter = this.calculateRotationCenter();
             this.setRotationCenter.apply(this, rotationCenter);
             this.emit(Skin.Events.WasAltered);

src/ShaderManager.js

@@ -154,15 +154,10 @@ ShaderManager.EFFECTS = Object.keys(ShaderManager.EFFECT_INFO);
  */
 ShaderManager.DRAW_MODE = {
     /**
-     * Draw normally. Its output will use premultiplied alpha.
+     * Draw normally.
      */
     default: 'default',
 
-    /**
-     * Draw with non-premultiplied alpha. Useful for reading pixels from GL into an ImageData object.
-     */
-    straightAlpha: 'straightAlpha',
-
     /**
      * Draw a silhouette using a solid color.
      */
@@ -174,9 +169,14 @@ ShaderManager.DRAW_MODE = {
     colorMask: 'colorMask',
 
     /**
-     * Draw a line with caps.
+     * Sample a "texture" to draw a line with caps.
      */
-    line: 'line'
+    lineSample: 'lineSample',
+
+    /**
+     * Draw normally except for pre-multiplied alpha
+     */
+    stamp: 'stamp'
 };
 
 module.exports = ShaderManager;

src/Silhouette.js

@@ -20,7 +20,7 @@ let __SilhouetteUpdateCanvas;
  * @return {number} Alpha value for x/y position
  */
 const getPoint = ({_width: width, _height: height, _colorData: data}, x, y) => {
-    // 0 if outside bounds, otherwise read from data.
+    // 0 if outside bouds, otherwise read from data.
     if (x >= width || y >= height || x < 0 || y < 0) {
         return 0;
     }
@@ -39,7 +39,6 @@ const __cornerWork = [
 
 /**
  * Get the color from a given silhouette at an x/y local texture position.
- * Multiply color values by alpha for proper blending.
  * @param {Silhouette} The silhouette to sample.
  * @param {number} x X position of texture (0-1).
  * @param {number} y Y position of texture (0-1).
@@ -47,31 +46,7 @@ const __cornerWork = [
  * @return {Uint8ClampedArray} The dst vector.
  */
 const getColor4b = ({_width: width, _height: height, _colorData: data}, x, y, dst) => {
-    // 0 if outside bounds, otherwise read from data.
-    if (x >= width || y >= height || x < 0 || y < 0) {
-        return dst.fill(0);
-    }
-    const offset = ((y * width) + x) * 4;
-    // premultiply alpha
-    const alpha = data[offset + 3] / 255;
-    dst[0] = data[offset] * alpha;
-    dst[1] = data[offset + 1] * alpha;
-    dst[2] = data[offset + 2] * alpha;
-    dst[3] = data[offset + 3];
-    return dst;
-};
-
-/**
- * Get the color from a given silhouette at an x/y local texture position.
- * Do not multiply color values by alpha, as it has already been done.
- * @param {Silhouette} The silhouette to sample.
- * @param {number} x X position of texture (0-1).
- * @param {number} y Y position of texture (0-1).
- * @param {Uint8ClampedArray} dst A color 4b space.
- * @return {Uint8ClampedArray} The dst vector.
- */
-const getPremultipliedColor4b = ({_width: width, _height: height, _colorData: data}, x, y, dst) => {
-    // 0 if outside bounds, otherwise read from data.
+    // 0 if outside bouds, otherwise read from data.
     if (x >= width || y >= height || x < 0 || y < 0) {
         return dst.fill(0);
     }
@@ -103,21 +78,15 @@ class Silhouette {
          */
         this._colorData = null;
 
-        // By default, silhouettes are assumed not to contain premultiplied image data,
-        // so when we get a color, we want to multiply it by its alpha channel.
-        // Point `_getColor` to the version of the function that multiplies.
-        this._getColor = getColor4b;
-
         this.colorAtNearest = this.colorAtLinear = (_, dst) => dst.fill(0);
     }
 
     /**
      * Update this silhouette with the bitmapData for a skin.
-     * @param {ImageData|HTMLCanvasElement|HTMLImageElement} bitmapData An image, canvas or other element that the skin
-     * @param {boolean} isPremultiplied True if the source bitmap data comes premultiplied (e.g. from readPixels).
+     * @param {*} bitmapData An image, canvas or other element that the skin
      * rendering can be queried from.
      */
-    update (bitmapData, isPremultiplied = false) {
+    update (bitmapData) {
         let imageData;
         if (bitmapData instanceof ImageData) {
             // If handed ImageData directly, use it directly.
@@ -140,12 +109,6 @@ class Silhouette {
             imageData = ctx.getImageData(0, 0, width, height);
         }
 
-        if (isPremultiplied) {
-            this._getColor = getPremultipliedColor4b;
-        } else {
-            this._getColor = getColor4b;
-        }
-
         this._colorData = imageData.data;
         // delete our custom overriden "uninitalized" color functions
         // let the prototype work for itself
@@ -161,7 +124,7 @@ class Silhouette {
      * @returns {Uint8ClampedArray} dst
      */
     colorAtNearest (vec, dst) {
-        return this._getColor(
+        return getColor4b(
             this,
             Math.floor(vec[0] * (this._width - 1)),
             Math.floor(vec[1] * (this._height - 1)),
@@ -188,10 +151,10 @@ class Silhouette {
         const xFloor = Math.floor(x);
         const yFloor = Math.floor(y);
 
-        const x0y0 = this._getColor(this, xFloor, yFloor, __cornerWork[0]);
-        const x1y0 = this._getColor(this, xFloor + 1, yFloor, __cornerWork[1]);
-        const x0y1 = this._getColor(this, xFloor, yFloor + 1, __cornerWork[2]);
-        const x1y1 = this._getColor(this, xFloor + 1, yFloor + 1, __cornerWork[3]);
+        const x0y0 = getColor4b(this, xFloor, yFloor, __cornerWork[0]);
+        const x1y0 = getColor4b(this, xFloor + 1, yFloor, __cornerWork[1]);
+        const x0y1 = getColor4b(this, xFloor, yFloor + 1, __cornerWork[2]);
+        const x1y1 = getColor4b(this, xFloor + 1, yFloor + 1, __cornerWork[3]);
 
         dst[0] = (x0y0[0] * x0D * y0D) + (x0y1[0] * x0D * y1D) + (x1y0[0] * x1D * y0D) + (x1y1[0] * x1D * y1D);
         dst[1] = (x0y0[1] * x0D * y0D) + (x0y1[1] * x0D * y1D) + (x1y0[1] * x1D * y0D) + (x1y1[1] * x1D * y1D);

src/Skin.js

@@ -33,9 +33,6 @@ class Skin extends EventEmitter {
         /** @type {Vec3} */
         this._rotationCenter = twgl.v3.create(0, 0);
 
-        /** @type {WebGLTexture} */
-        this._texture = null;
-
         /**
          * The uniforms to be used by the vertex and pixel shaders.
          * Some of these are used by other parts of the renderer as well.
@@ -79,6 +76,13 @@ 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.
      */
@@ -167,23 +171,6 @@ class Skin extends EventEmitter {
      */
     updateSilhouette () {}
 
-    /**
-     * Set this skin's texture to the given image.
-     * @param {ImageData|HTMLCanvasElement} textureData - The canvas or image data to set the texture to.
-     */
-    _setTexture (textureData) {
-        const gl = this._renderer.gl;
-
-        gl.bindTexture(gl.TEXTURE_2D, this._texture);
-        // Premultiplied alpha is necessary for proper blending.
-        // See http://www.realtimerendering.com/blog/gpus-prefer-premultiplication/
-        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, true);
-        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textureData);
-        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, false);
-
-        this._silhouette.update(textureData);
-    }
-
     /**
      * Set the contents of this skin to an empty skin.
      * @fires Skin.event:WasAltered
@@ -212,9 +199,6 @@ class Skin extends EventEmitter {
             this._emptyImageTexture = twgl.createTexture(gl, textureOptions);
         }
 
-        this._rotationCenter[0] = 0;
-        this._rotationCenter[1] = 0;
-
         this._silhouette.update(this._emptyImageData);
         this.emit(Skin.Events.WasAltered);
     }

src/TextBubbleSkin.js

@@ -42,6 +42,9 @@ class TextBubbleSkin extends Skin {
         /** @type {HTMLCanvasElement} */
         this._canvas = document.createElement('canvas');
 
+        /** @type {WebGLTexture} */
+        this._texture = null;
+
         /** @type {Array<number>} */
         this._size = [0, 0];
 
@@ -269,7 +272,9 @@ class TextBubbleSkin extends Skin {
                 this._texture = twgl.createTexture(gl, textureOptions);
             }
 
-            this._setTexture(textureData);
+            gl.bindTexture(gl.TEXTURE_2D, this._texture);
+            gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textureData);
+            this._silhouette.update(textureData);
         }
 
         return this._texture;

src/shaders/sprite.frag

@@ -33,26 +33,24 @@ uniform float u_mosaic;
 uniform float u_ghost;
 #endif // ENABLE_ghost
 
-#ifdef DRAW_MODE_line
+#ifdef DRAW_MODE_lineSample
 uniform vec4 u_lineColor;
-uniform float u_lineThickness;
-uniform vec4 u_penPoints;
-#endif // DRAW_MODE_line
+uniform float u_capScale;
+uniform float u_aliasAmount;
+#endif // DRAW_MODE_lineSample
 
 uniform sampler2D u_skin;
 
 varying vec2 v_texCoord;
 
-// Add this to divisors to prevent division by 0, which results in NaNs propagating through calculations.
-// Smaller values can cause problems on some mobile devices.
-const float epsilon = 1e-3;
-
 #if !defined(DRAW_MODE_silhouette) && (defined(ENABLE_color))
 // Branchless color conversions based on code from:
 // http://www.chilliant.com/rgb2hsv.html by Ian Taylor
 // Based in part on work by Sam Hocevar and Emil Persson
 // See also: https://en.wikipedia.org/wiki/HSL_and_HSV#Formal_derivation
 
+// Smaller values can cause problems on some mobile devices
+const float epsilon = 1e-3;
 
 // Convert an RGB color to Hue, Saturation, and Value.
 // All components of input and output are expected to be in the [0,1] range.
@@ -109,7 +107,7 @@ const vec2 kCenter = vec2(0.5, 0.5);
 
 void main()
 {
-	#ifndef DRAW_MODE_line
+	#ifndef DRAW_MODE_lineSample
 	vec2 texcoord0 = v_texCoord;
 
 	#ifdef ENABLE_mosaic
@@ -155,12 +153,16 @@ void main()
 
 	gl_FragColor = texture2D(u_skin, texcoord0);
 
-	#if defined(ENABLE_color) || defined(ENABLE_brightness)
-	// Divide premultiplied alpha values for proper color processing
-	// Add epsilon to avoid dividing by 0 for fully transparent pixels
-	gl_FragColor.rgb = clamp(gl_FragColor.rgb / (gl_FragColor.a + epsilon), 0.0, 1.0);
+    #ifdef ENABLE_ghost
+    gl_FragColor.a *= u_ghost;
+    #endif // ENABLE_ghost
 
-	#ifdef ENABLE_color
+	#ifdef DRAW_MODE_silhouette
+	// switch to u_silhouetteColor only AFTER the alpha test
+	gl_FragColor = u_silhouetteColor;
+	#else // DRAW_MODE_silhouette
+
+	#if defined(ENABLE_color)
 	{
 		vec3 hsv = convertRGB2HSV(gl_FragColor.xyz);
 
@@ -176,29 +178,11 @@ void main()
 
 		gl_FragColor.rgb = convertHSV2RGB(hsv);
 	}
-	#endif // ENABLE_color
+	#endif // defined(ENABLE_color)
 
-	#ifdef ENABLE_brightness
+	#if defined(ENABLE_brightness)
 	gl_FragColor.rgb = clamp(gl_FragColor.rgb + vec3(u_brightness), vec3(0), vec3(1));
-	#endif // ENABLE_brightness
-
-	// Re-multiply color values
-	gl_FragColor.rgb *= gl_FragColor.a + epsilon;
-
-	#endif // defined(ENABLE_color) || defined(ENABLE_brightness)
-
-	#ifdef ENABLE_ghost
-	gl_FragColor *= u_ghost;
-	#endif // ENABLE_ghost
-
-	#ifdef DRAW_MODE_silhouette
-	// Discard fully transparent pixels for stencil test
-	if (gl_FragColor.a == 0.0) {
-		discard;
-	}
-	// switch to u_silhouetteColor only AFTER the alpha test
-	gl_FragColor = u_silhouetteColor;
-	#else // DRAW_MODE_silhouette
+	#endif // defined(ENABLE_brightness)
 
 	#ifdef DRAW_MODE_colorMask
 	vec3 maskDistance = abs(gl_FragColor.rgb - u_colorMask);
@@ -210,31 +194,15 @@ void main()
 	#endif // DRAW_MODE_colorMask
 	#endif // DRAW_MODE_silhouette
 
-	#ifdef DRAW_MODE_straightAlpha
-	// Un-premultiply alpha.
-	gl_FragColor.rgb /= gl_FragColor.a + epsilon;
-	#endif
-  
-	#else // DRAW_MODE_line
-	// Maaaaagic antialiased-line-with-round-caps shader.
-	// Adapted from Inigo Quilez' 2D distance function cheat sheet
-	// https://www.iquilezles.org/www/articles/distfunctions2d/distfunctions2d.htm
-
-	// The xy component of u_penPoints is the first point; the zw is the second point.
-	// This is done to minimize the number of gl.uniform calls, which can add up.
-	vec2 pa = v_texCoord - u_penPoints.xy, ba = u_penPoints.zw - u_penPoints.xy;
-	// Magnitude of vector projection of this fragment onto the line (both relative to the line's start point).
-	// This results in a "linear gradient" which goes from 0.0 at the start point to 1.0 at the end point.
-	float projMagnitude = clamp(dot(pa, ba) / dot(ba, ba), 0.0, 1.0);
-
-	float lineDistance = length(pa - (ba * projMagnitude));
-
-	// The distance to the line allows us to create lines of any thickness.
-	// Instead of checking whether this fragment's distance < the line thickness,
-	// utilize the distance field to get some antialiasing. Fragments far away from the line are 0,
-	// fragments close to the line are 1, and fragments that are within a 1-pixel border of the line are in between.
-	float cappedLine = clamp((u_lineThickness + 1.0) * 0.5 - lineDistance, 0.0, 1.0);
-
-	gl_FragColor = u_lineColor * cappedLine;
-	#endif // DRAW_MODE_line
+	#else // DRAW_MODE_lineSample
+	gl_FragColor = u_lineColor;
+	gl_FragColor.a *= clamp(
+		// Scale the capScale a little to have an aliased region.
+		(u_capScale + u_aliasAmount -
+			u_capScale * 2.0 * distance(v_texCoord, vec2(0.5, 0.5))
+		) / (u_aliasAmount + 1.0),
+		0.0,
+		1.0
+	);
+	#endif // DRAW_MODE_lineSample
 }

src/shaders/sprite.vert

@@ -1,57 +1,22 @@
-precision mediump float;
-
-#ifdef DRAW_MODE_line
-uniform vec2 u_stageSize;
-uniform float u_lineThickness;
-uniform vec4 u_penPoints;
-
-// Add this to divisors to prevent division by 0, which results in NaNs propagating through calculations.
-// Smaller values can cause problems on some mobile devices.
-const float epsilon = 1e-3;
-#endif
-
-#ifndef DRAW_MODE_line
 uniform mat4 u_projectionMatrix;
 uniform mat4 u_modelMatrix;
-attribute vec2 a_texCoord;
-#endif
 
 attribute vec2 a_position;
+attribute vec2 a_texCoord;
 
 varying vec2 v_texCoord;
 
+#ifdef DRAW_MODE_lineSample
+uniform float u_positionScalar;
+#endif
+
 void main() {
-	#ifdef DRAW_MODE_line
-	// Calculate a rotated ("tight") bounding box around the two pen points.
-	// Yes, we're doing this 6 times (once per vertex), but on actual GPU hardware,
-	// it's still faster than doing it in JS combined with the cost of uniformMatrix4fv.
-
-	// Expand line bounds by sqrt(2) / 2 each side-- this ensures that all antialiased pixels
-	// fall within the quad, even at a 45-degree diagonal
-	vec2 position = a_position;
-	float expandedRadius = (u_lineThickness * 0.5) + 1.4142135623730951;
-
-	float lineLength = length(u_penPoints.zw - u_penPoints.xy);
-
-	position.x *= lineLength + (2.0 * expandedRadius);
-	position.y *= 2.0 * expandedRadius;
-
-	// Center around first pen point
-	position -= expandedRadius;
-
-	// Rotate quad to line angle
-	vec2 normalized = (u_penPoints.zw - u_penPoints.xy + epsilon) / (lineLength + epsilon);
-	position = mat2(normalized.x, normalized.y, -normalized.y, normalized.x) * position;
-	// Translate quad
-	position += u_penPoints.xy;
-
-	// Apply view transform
-	position *= 2.0 / u_stageSize;
-
-	gl_Position = vec4(position, 0, 1);
-	v_texCoord = position * 0.5 * u_stageSize;
-	#else
-	gl_Position = u_projectionMatrix * u_modelMatrix * vec4(a_position, 0, 1);
-	v_texCoord = a_texCoord;
-	#endif
+    #ifdef DRAW_MODE_lineSample
+    vec2 position = a_position;
+    position.y = clamp(position.y * u_positionScalar, -0.5, 0.5);
+    gl_Position = u_projectionMatrix * u_modelMatrix * vec4(position, 0, 1);
+    #else
+    gl_Position = u_projectionMatrix * u_modelMatrix * vec4(a_position, 0, 1);
+    #endif
+    v_texCoord = a_texCoord;
 }