refine canvas.

Runtime/foundation/node.mixin.gen.cs

         static readonly Dictionary<_DependencyList, WeakReference> _canonicalObjects =
             new Dictionary<_DependencyList, WeakReference>();
 
-        public bool pure { get; set; } // pure = false, if canonicalEquals should not be used.
+        public bool pureWidget { get; set; } // pure = false, if canonicalEquals should not be used.
 
         public override bool Equals(object obj) {
             if (ReferenceEquals(null, obj)) {
                 return false;
             }
 
-            if (!this.pure) {
+            if (!this.pureWidget) {
                 return ReferenceEquals(this, obj);
             } else {
                 return ReferenceEquals(this._getCanonical(), ((CanonicalMixinDiagnosticableTree) obj)._getCanonical());

Runtime/foundation/node.mixin.njk

         static readonly Dictionary<_DependencyList, WeakReference> _canonicalObjects =
             new Dictionary<_DependencyList, WeakReference>();
         
-        public bool alwaysUpdate { get; set; } // if canonicalEquals should not be used.
+        public bool pureWidget { get; set; } // if canonicalEquals should not be used.
 
         public override bool Equals(object obj) {
             if (ReferenceEquals(null, obj)) {
                 return false;
             }
 
-            if (!this.pure) {
+            if (!this.pureWidget) {
                 return ReferenceEquals(this, obj);
             } else {
                 return ReferenceEquals(this._getCanonical(), ((CanonicalMixin{{with}}) obj)._getCanonical());

Runtime/ui/painting/canvas_impl.cs

                 height = textureHeight,
                 layerBounds = maskBounds,
                 filterMode = FilterMode.Bilinear,
+                noMSAA = true,
             };
 
             parentLayer.addLayer(maskLayer);
                 height = textureHeight,
                 layerBounds = maskLayer.layerBounds,
                 filterMode = FilterMode.Bilinear,
+                noMSAA = true,
             };
 
             parentLayer.addLayer(blurXLayer);
                 height = textureHeight,
                 layerBounds = maskLayer.layerBounds,
                 filterMode = FilterMode.Bilinear,
+                noMSAA = true,
             };
 
             parentLayer.addLayer(blurYLayer);
 
         public void flush(Picture picture) {
             this._reset();
-            
+
-            
+
             D.assert(this._layers.Count == 1);
             D.assert(this._layers[0].states.Count == 1);
 
 
             using (var cmdBuf = new CommandBuffer()) {
                 cmdBuf.name = "CommandBufferCanvas";
+
+                this._lastRtID = -1;
+
+                // this is necessary for webgl2. not sure why... just to be safe to disable the scissor.
+                cmdBuf.DisableScissorRect();
+
-        
-         void _drawLayer(RenderLayer layer, CommandBuffer cmdBuf) {
-             if (layer.rtID == 0) {
-                 cmdBuf.SetRenderTarget(this._renderTexture);
-                 cmdBuf.ClearRenderTarget(true, true, UnityEngine.Color.clear);
-             }
-             else {
-                 cmdBuf.SetRenderTarget(layer.rtID);
-                 cmdBuf.ClearRenderTarget(true, true, UnityEngine.Color.clear);
-             }
+
+        int _lastRtID;
+
+        void _setRenderTarget(CommandBuffer cmdBuf, int rtID, ref bool toClear) {
+            if (this._lastRtID == rtID) {
+                return;
+            }
+
+            this._lastRtID = rtID;
+            
+            if (rtID == 0) {
+                cmdBuf.SetRenderTarget(this._renderTexture);
+            } else {
+                cmdBuf.SetRenderTarget(rtID);
+            }
+            
+            if (toClear) {
+                cmdBuf.ClearRenderTarget(true, true, UnityEngine.Color.clear);
+                toClear = false;
+            }
+        }
+
+        void _drawLayer(RenderLayer layer, CommandBuffer cmdBuf) {
+            bool toClear = true;
-             foreach (var cmdObj in layer.draws) {
+            foreach (var cmdObj in layer.draws) {
                 switch (cmdObj) {
                     case CmdLayer cmd:
                         var subLayer = cmd.layer;
                             useMipMap = false,
                             autoGenerateMips = false,
                         };
-                
-                        if (this._renderTexture.antiAliasing != 0) {
+
+                        if (this._renderTexture.antiAliasing != 0 && !subLayer.noMSAA) {
-                
+
-                        
-                        if (layer.rtID == 0) {
-                            cmdBuf.SetRenderTarget(this._renderTexture);
-                        }
-                        else {
-                            cmdBuf.SetRenderTarget(layer.rtID);
-                        }
+                        this._setRenderTarget(cmdBuf, layer.rtID, ref toClear);
+                        
                         if (cmd.layer != null) {
                             if (cmd.layer.rtID == 0) {
                                 cmdBuf.SetGlobalTexture(CmdDraw.texId, this._renderTexture);
                         if (mesh == null) {
                             continue;
                         }
-                        
-                        D.assert(mesh.vertices.Count > 0);  
+
+                        D.assert(mesh.vertices.Count > 0);
                         cmd.meshObj.SetVertices(mesh.vertices);
                         cmd.meshObj.SetTriangles(mesh.triangles, 0, false);
                         cmd.meshObj.SetUVs(0, mesh.uv);
             foreach (var subLayer in layer.layers) {
                 cmdBuf.ReleaseTemporaryRT(subLayer.rtID);
             }
-            
-            if (layer.rtID == 0) {
-                // this is necessary for webgl2. not sure why... just to be safe to disable the scissor.
-                cmdBuf.DisableScissorRect();
-            }
         }
 
         void _clearLayer(RenderLayer layer) {
             public int width;
             public int height;
             public FilterMode filterMode = FilterMode.Point;
+            public bool noMSAA = false;
             public Rect layerBounds;
             public Paint layerPaint;
             public readonly List<object> draws = new List<object>();