feat: add custom shader support for CompositeCanvasRenderer

Packages/src/Runtime/CompositeCanvasRenderer.cs

@@ -743,13 +743,27 @@ private Material CreateMaterial()
             return CreateMaterial(colorMode, srcBlendMode, dstBlendMode);
         }
 
+        /// <summary>
+        /// Get shader to use based on project settings.
+        /// </summary>
+        private static Shader GetShaderToUse()
+        {
+            var customShader = CompositeCanvasRendererProjectSettings.customShader;
+            if (customShader != null)
+            {
+                return customShader;
+            }
+
+            return Shader.Find("UI/CompositeCanvasRenderer");
+        }
+
         /// <summary>
         /// Create a material.
         /// </summary>
         public static Material CreateMaterial(ColorMode colorMode, BlendMode srcBlendMode, BlendMode dstBlendMode)
         {
             Profiler.BeginSample("(CCR)[CompositeCanvasRenderer] CreateMaterial");
-            var mat = new Material(Shader.Find("UI/CompositeCanvasRenderer"))
+            var mat = new Material(GetShaderToUse())
             {
                 hideFlags = HideFlags.DontSave | HideFlags.NotEditable,
                 shaderKeywords = s_ColorModeKeywords[(int)colorMode]

Packages/src/Runtime/ProjectSettings/CompositeCanvasRendererProjectSettings.cs

@@ -19,6 +19,11 @@ public class CompositeCanvasRendererProjectSettings
         [SerializeField]
         private bool m_EnableCullingInEditMode = true;
 
+        [Header("CompositeCanvasRenderer Shader Override")]
+        [SerializeField]
+        [Tooltip("Alternative shader to use instead of 'UI/CompositeCanvasRenderer'.\nLeave empty to use the default shader.")]
+        private Shader m_CustomShader;
+
 #if UNITY_EDITOR
         [Header("Shader")]
         [SerializeField]
@@ -59,6 +64,12 @@ public static float sensitivity
             }
         }
 
+        public static Shader customShader
+        {
+            get => instance.m_CustomShader;
+            set => instance.m_CustomShader = value;
+        }
+
 #if UNITY_EDITOR
         /// <summary>
         /// Reset to default values.

Packages/src/Shaders/UI-CompositeCanvasRenderer.shader

@@ -199,7 +199,8 @@ Shader "UI/CompositeCanvasRenderer"
                 color *= tex2D(_MaskTex, maskUv + _Time.y * _MaskSpeed).a;
                 #endif
 
-                return applyColor(color, IN.color);
+                half4 colorFactor = half4(IN.color.rgb, IN.color.a * color.a);
+                return applyColor(color, colorFactor);
             }
             ENDCG
         }