const vertex handle

hw3d/App.cpp

@@ -13,7 +13,7 @@
 #include <assimp/Importer.hpp>
 #include <assimp/scene.h>
 #include <assimp/postprocess.h>
-#include "VertexLayout.h"
+#include "Vertex.h"
 
 namespace dx = DirectX;
 
@@ -42,6 +42,8 @@ void f()
 	auto tex = vb[1].Attr<VertexLayout::Texture2D>();
 	vb.Back().Attr<VertexLayout::Position3D>().z = 420.0f;
 	pos = vb.Back().Attr<VertexLayout::Position3D>();
+	const auto& cvb = vb;
+	pos = cvb[1].Attr<VertexLayout::Position3D>();
 }
 
 App::App()

hw3d/VertexLayout.h → hw3d/Vertex.h

@@ -62,7 +62,7 @@ public:
 			case Float4Color:
 				return sizeof( XMFLOAT3 );
 			case BGRAColor:
-				return sizeof( unsigned int );
+				return sizeof( ::BGRAColor );
 			}
 			assert( "Invalid element type" && false );
 			return 0u;
@@ -188,7 +188,7 @@ public:
 			assert( "Bad element type" && false );
 		}	
 	}
-private:
+protected:
 	Vertex( char* pData,const VertexLayout& layout ) noexcept(!IS_DEBUG)
 		:
 		pData( pData ),
@@ -196,6 +196,7 @@ private:
 	{
 		assert( pData != nullptr );
 	}
+private:
 	template<typename First,typename ...Rest>
 	// enables parameter pack setting of multiple parameters by element index
 	void SetAttributeByIndex( size_t i,First&& first,Rest&&... rest ) noexcept(!IS_DEBUG)
@@ -221,6 +222,22 @@ private:
 	const VertexLayout& layout;
 };
 
+class ConstVertex
+{
+public:
+	ConstVertex( const Vertex& v ) noexcept(!IS_DEBUG)
+		:
+		vertex( v )
+	{}
+	template<VertexLayout::ElementType Type>
+	const auto& Attr() const noexcept(!IS_DEBUG)
+	{
+		return const_cast<Vertex&>(vertex).Attr<Type>();
+	}
+private:
+	Vertex vertex;
+};
+
 class VertexBuffer
 {
 public:
@@ -258,6 +275,18 @@ public:
 		assert( i < Size() );
 		return Vertex{ buffer.data() + layout.Size() * i,layout };
 	}
+	ConstVertex Back() const noexcept(!IS_DEBUG)
+	{
+		return const_cast<VertexBuffer*>(this)->Back();
+	}
+	ConstVertex Front() const noexcept(!IS_DEBUG)
+	{
+		return const_cast<VertexBuffer*>(this)->Front();
+	}
+	ConstVertex operator[]( size_t i ) const noexcept(!IS_DEBUG)
+	{
+		return const_cast<VertexBuffer&>(*this)[i];
+	}
 private:
 	std::vector<char> buffer;
 	VertexLayout layout;