TextureComponentMapping: added operator* that combines two swizzles i…

…nto one

Graphics/GraphicsEngine/interface/TextureView.h

@@ -175,6 +175,38 @@ struct TextureComponentMapping
             TEXTURE_COMPONENT_SWIZZLE_IDENTITY
         };
     }
+
+    // Combines two component mappings into one.
+    // The resulting mapping is equivalent to first applying the first (lhs) mapping,
+    // then applying the second (rhs) mapping.
+    TextureComponentMapping operator*(const TextureComponentMapping& Rhs) const
+	{
+        TextureComponentMapping CombinedMapping;
+        for (size_t c = 0; c < 4; ++c)
+        {
+        	TEXTURE_COMPONENT_SWIZZLE  RhsCompSwizzle = Rhs[c];
+            TEXTURE_COMPONENT_SWIZZLE& DstCompSwizzle = CombinedMapping[c];
+            switch(RhsCompSwizzle)
+            {
+                case TEXTURE_COMPONENT_SWIZZLE_IDENTITY: DstCompSwizzle = (*this)[c]; break;
+                case TEXTURE_COMPONENT_SWIZZLE_ZERO:     DstCompSwizzle = TEXTURE_COMPONENT_SWIZZLE_ZERO; break;
+                case TEXTURE_COMPONENT_SWIZZLE_ONE:      DstCompSwizzle = TEXTURE_COMPONENT_SWIZZLE_ONE; break;
+                case TEXTURE_COMPONENT_SWIZZLE_R:        DstCompSwizzle = R; break;
+                case TEXTURE_COMPONENT_SWIZZLE_G:        DstCompSwizzle = G; break;
+                case TEXTURE_COMPONENT_SWIZZLE_B:        DstCompSwizzle = B; break;
+                case TEXTURE_COMPONENT_SWIZZLE_A:        DstCompSwizzle = A; break;
+                default: DstCompSwizzle = (*this)[c]; break;
+            }
+        }
+        static_assert(TEXTURE_COMPONENT_SWIZZLE_COUNT == 7, "Please handle the new component swizzle");
+        return CombinedMapping;
+	}
+
+    TextureComponentMapping& operator*=(const TextureComponentMapping& rhs)
+    {
+        *this = *this * rhs;
+        return *this;
+    }
 #endif
 };
 typedef struct TextureComponentMapping TextureComponentMapping;