fast shadow fix some artifacts

Author: zhuxingwei

Runtime/Resources/UIWidgets_canvas_shadowRBox.shader

@@ -5,18 +5,28 @@ Shader "UIWidgets/ShadowRBox"
     {
         _SrcBlend("_SrcBlend", Int) = 1 // One
         _DstBlend("_DstBlend", Int) = 10 // OneMinusSrcAlpha
+        _StencilComp("_StencilComp", Float) = 8 // - Equal, 8 - Always 
     }
     SubShader
     {
+        ZTest Always
+        ZWrite Off
         Blend [_SrcBlend] [_DstBlend]
+        
+        Stencil {
+            Ref 128
+            Comp [_StencilComp]
+        }
+        
         Pass {
             CGPROGRAM
 
             float4 box;
-            float2 window;
+            float4 _viewport;
             float sigma;
             float4 color;
             float corner;
+            float _mat[9];
 
             struct appdata
             {
@@ -81,7 +91,14 @@ Shader "UIWidgets/ShadowRBox"
                 v2f o;
                 float padding = 3.0 * sigma;
                 o.coord = lerp(box.xy - padding, box.zw + padding, v.vertex.xy);
-                o.vertex = float4(o.coord.x * 2.0 /window.x - 1.0, o.coord.y * 2.0/window.y - 1.0, 0, 1);
+                float3x3 mat = float3x3(_mat[0], _mat[1], _mat[2], _mat[3], _mat[4], _mat[5], 0, 0, 1);
+                float2 p = mul(mat, float3(o.coord.xy, 1.0)).xy - _viewport.xy;
+                
+            #if UNITY_UV_STARTS_AT_TOP
+                o.vertex = float4(2.0 * p.x / _viewport.z - 1.0, 2.0 * p.y / _viewport.w - 1.0, 0, 1);
+            #else
+                o.vertex = float4(2.0 * p.x / _viewport.z - 1.0, 1.0 - 2.0 * p.y / _viewport.w, 0, 1);
+            #endif
                 return o;
             }
 

Runtime/ui/painting/shadow_utils.cs

@@ -12,7 +12,7 @@ static class ShadowUtils {
 
         const float kMaxAmbientRadius = 300 * kAmbientHeightFactor * kAmbientGeomFactor;
 
-        const bool debugShadow = true;
+        const bool debugShadow = false;
 
         static float divideAndPin(float numer, float denom, float min, float max) {
             return (numer / denom).clamp(min, max);

Runtime/ui/renderer/cmdbufferCanvas/rendering/canvas_impl.cs

@@ -1044,6 +1044,9 @@ void _drawLayer(RenderLayer layer, CommandBuffer cmdBuf) {
 
                         break;
                     case CmdDraw cmd:
+                        if (cmd.material != CanvasShader.shadowBox) {
+                            
+                        }
                         this._setRenderTarget(cmdBuf, layer.rtID, ref toClear);
 
                         if (cmd.layerId != null) {

Runtime/ui/renderer/cmdbufferCanvas/rendering/canvas_shader.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 using UnityEngine;
 using UnityEngine.Rendering;
 
@@ -188,6 +189,8 @@ static CanvasShader() {
             _shadowRBox = new Material(shadowRBoxShader) {hideFlags = HideFlags.HideAndDontSave};
         }
 
+        public static Material shadowBox => _shadowBox;
+
         static readonly int _viewportId = Shader.PropertyToID("_viewport");
         static readonly int _alphaId = Shader.PropertyToID("_alpha");
         static readonly int _colorId = Shader.PropertyToID("_color");
@@ -206,8 +209,9 @@ static CanvasShader() {
 
 
         static readonly int _shadowBoxId = Shader.PropertyToID("box");
-        static readonly int _shadowSigma = Shader.PropertyToID("sigma");
-        static readonly int _shadowColor = Shader.PropertyToID("color");
+        static readonly int _shadowSigmaId = Shader.PropertyToID("sigma");
+        static readonly int _shadowColorId = Shader.PropertyToID("color");
+        static readonly int _shadowCornerId = Shader.PropertyToID("corner");
 
         static Vector4 _colorToVector4(uiColor c) {
             return new Vector4(
@@ -501,19 +505,22 @@ public static PictureFlusher.CmdDraw maskFilter(PictureFlusher.RenderLayer layer
         }
 
         public static PictureFlusher.CmdDraw fastShadow(PictureFlusher.RenderLayer layer, uiMeshMesh mesh,
-            bool isRect, Vector4 bound) {
+            bool isRect, Vector4 bound, uiColor color) {
             Vector4 viewport = layer.viewport;
             var mat = _shadowBox;
-            //if (isRect) {
-            //    mat = _shadowBox;
-            //}
+            if (!isRect) {
+                mat = _shadowRBox;
+            }
 
             //use props to set all the uniforms !!!!!
             var props = ObjectPool<MaterialPropertyBlockWrapper>.alloc();
             props.SetVector(_viewportId, viewport);
-            props.SetFloat(_shadowSigma, 3f);
+            props.SetFloat(_shadowSigmaId, 3f);
             props.SetVector(_shadowBoxId, bound);
-            props.SetVector(_shadowColor, new Vector4(0, 0, 0, 1));
+            props.SetVector(_shadowColorId, _colorToVector4(color));
+            if (!isRect) {
+                props.SetFloat(_shadowCornerId, 30f);
+            }
 
             return PictureFlusher.CmdDraw.create(
                 mesh: mesh,

Runtime/ui/renderer/cmdbufferCanvas/rendering/canvas_shadow_utils.cs

@@ -7,6 +7,10 @@ public partial class PictureFlusher {
         void _drawRRectShadow(uiPath path, uiPaint paint) {
             D.assert(path.isRRect, () => "Cannot draw Shadow for non-RRect shapes");
             D.assert(paint.style == PaintingStyle.fill, () => "Cannot draw Shadow for stroke lines");
+            var bound = path.getBounds();
+            if (!this._applyClip(bound)) {
+                return;
+            }
 
             var layer = this._currentLayer;
             var state = layer.currentState;
@@ -28,9 +32,7 @@ void _drawRRectShadow(uiPath path, uiPaint paint) {
             _triangles.Add(3);
 
             var mesh = uiMeshMesh.create(state.matrix, vertices, _triangles);
-            var bound = path.getBounds();
-            Debug.Log("Draw shadow>>> " + bound.top);
-            layer.draws.Add(CanvasShader.fastShadow(layer, mesh, path.isRect, new Vector4(bound.left, bound.top, bound.right, bound.bottom)));
+            layer.draws.Add(CanvasShader.fastShadow(layer, mesh, path.isRect, new Vector4(bound.left, bound.top, bound.right, bound.bottom), paint.color));
         }
 
     }