fix: calculate convex hulls in texture space

Author: adroitwhiz

src/Drawable.js

@@ -596,16 +596,13 @@ class Drawable {
         }
 
         const projection = twgl.m4.ortho(-1, 1, -1, 1, -1, 1);
-        const skinSize = this.skin.size;
-        const halfXPixel = 1 / skinSize[0] / 2;
-        const halfYPixel = 1 / skinSize[1] / 2;
         const tm = twgl.m4.multiply(this._uniforms.u_modelMatrix, projection);
         for (let i = 0; i < this._convexHullPoints.length; i++) {
             const point = this._convexHullPoints[i];
             const dstPoint = this._transformedHullPoints[i];
 
-            dstPoint[0] = 0.5 + (-point[0] / skinSize[0]) - halfXPixel;
-            dstPoint[1] = (point[1] / skinSize[1]) - 0.5 + halfYPixel;
+            dstPoint[0] = 0.5 - point[0];
+            dstPoint[1] = point[1] - 0.5;
             twgl.m4.transformPoint(tm, dstPoint, dstPoint);
         }
 

src/RenderWebGL.js

@@ -1861,14 +1861,16 @@ class RenderWebGL extends EventEmitter {
     _getConvexHullPointsForDrawable (drawableID) {
         const drawable = this._allDrawables[drawableID];
 
-        const [width, height] = drawable.skin.size;
+        drawable.updateCPURenderAttributes();
+
+        const silhouette = drawable.skin._silhouette;
+        const width = silhouette._width;
+        const height = silhouette._height;
         // No points in the hull if invisible or size is 0.
         if (!drawable.getVisible() || width === 0 || height === 0) {
             return [];
         }
 
-        drawable.updateCPURenderAttributes();
-
         /**
          * Return the determinant of two vectors, the vector from A to B and the vector from A to C.
          *
@@ -1921,8 +1923,8 @@ class RenderWebGL extends EventEmitter {
             for (; x < width; x++) {
                 _pixelPos[0] = (x + 0.5) / width;
                 EffectTransform.transformPoint(drawable, _pixelPos, _effectPos);
-                if (drawable.skin.isTouchingLinear(_effectPos)) {
-                    currentPoint = [x, y];
+                if (drawable.skin.isTouchingNearest(_effectPos)) {
+                    currentPoint = [_pixelPos[0], _pixelPos[1]];
                     break;
                 }
             }
@@ -1958,8 +1960,8 @@ class RenderWebGL extends EventEmitter {
             for (x = width - 1; x >= 0; x--) {
                 _pixelPos[0] = (x + 0.5) / width;
                 EffectTransform.transformPoint(drawable, _pixelPos, _effectPos);
-                if (drawable.skin.isTouchingLinear(_effectPos)) {
-                    currentPoint = [x, y];
+                if (drawable.skin.isTouchingNearest(_effectPos)) {
+                    currentPoint = [_pixelPos[0], _pixelPos[1]];
                     break;
                 }
             }