Remove gfx::vertex, setup meshes using attributes directly

libs/gfx/include/psemek/gfx/mesh.hpp

@@ -19,6 +19,9 @@ namespace psemek::gfx
 	struct normalized
 	{};
 
+	struct skip
+	{};
+
 	template <typename Attrib>
 	struct attrib_traits;
 
@@ -132,111 +135,62 @@ namespace psemek::gfx
 		static constexpr GLboolean normalized = gl::TRUE_;
 	};
 
-	template <typename ... Attribs>
-	struct vertex
-	{
-		static constexpr std::size_t size = (0 + ... + sizeof(typename attrib_traits<Attribs>::attrib_type));
-
-		using attribs = std::tuple<Attribs...>;
-		using attrib_types = std::tuple<typename attrib_traits<Attribs>::attrib_type...>;
-
-		template <std::size_t I>
-		static constexpr std::size_t offset()
-		{
-			return offset_impl(std::make_index_sequence<I>{});
-		}
-
-		template <std::size_t I>
-		auto & get()
-		{
-			using T = std::tuple_element_t<I, attrib_types>;
-			return *reinterpret_cast<T *>(reinterpret_cast<char *>(&storage) + offset<I>());
-		}
-
-		template <std::size_t I>
-		auto const & get() const
-		{
-			using T = std::tuple_element_t<I, attrib_types>;
-			return *reinterpret_cast<T const *>(reinterpret_cast<char const *>(&storage) + offset<I>());
-		}
-
-		vertex() = default;
-
-		vertex(vertex const & other)
-		{
-			copy_impl(std::make_index_sequence<sizeof...(Attribs)>{}, other);
-		}
-
-		vertex (typename attrib_traits<Attribs>::attrib_type const & ... args)
-		{
-			construct_impl(std::make_index_sequence<sizeof...(Attribs)>{}, args...);
-		}
-
-		vertex & operator = (vertex const & other)
-		{
-			if (this != &other) copy_impl(std::make_index_sequence<sizeof...(Attribs)>{}, other);
-			return *this;
-		}
-
-		std::aligned_storage_t<size, std::max(std::initializer_list<std::size_t>{alignof(Attribs)...})> storage;
-
-	private:
-
-		template <std::size_t ... Is>
-		static constexpr std::size_t offset_impl(std::index_sequence<Is...>)
-		{
-			return (0 + ... + sizeof(std::tuple_element_t<Is, attrib_types>));
-		}
-
-		template <std::size_t ... Is>
-		void construct_impl(std::index_sequence<Is...>, typename attrib_traits<Attribs>::attrib_type const & ... args)
-		{
-			((get<Is>() = args), ...);
-		}
-
-		template <std::size_t ... Is>
-		void copy_impl(std::index_sequence<Is...>, vertex const & other)
-		{
-			((get<Is>() = other.get<Is>()), ...);
-		}
-	};
-
 	namespace detail
 	{
 
-		template <std::size_t ... Is>
+		template <typename Attr>
-		void enable_attribs(std::index_sequence<Is...>)
+		std::size_t attr_size()
 		{
-			int x[] { ((void) gl::EnableVertexAttribArray(Is), 0) ... };
+			if constexpr (std::is_same_v<Attr, skip>)
-			(void) x;
-		}
-
-		template <typename Vertex, std::size_t I>
-		void attrib_pointer()
 			{
-			using traits = attrib_traits<std::tuple_element_t<I, typename Vertex::attribs>>;
+				return 0;
-			gl::VertexAttribPointer(I, traits::size, traits::type, traits::normalized, sizeof(Vertex), reinterpret_cast<char const *>(Vertex::template offset<I>()));
 			}
-
+			else
-		template <typename Vertex, std::size_t ... Is>
-		void attrib_pointers(std::index_sequence<Is...>)
 			{
-			int x[] { ((void) attrib_pointer<Vertex, Is>(), 0) ... };
+				return sizeof(Attr);
-			(void) x;
+			}
 		}
-
-		template <typename Vertex>
-		struct mesh_setup;
 
 		template <typename ... Attribs>
-		struct mesh_setup<vertex<Attribs...>>
+		struct mesh_setup;
-		{
-			static void setup()
-			{
-				using indices = std::make_index_sequence<sizeof...(Attribs)>;
 
-				enable_attribs(indices{});
+		template <>
-				attrib_pointers<vertex<Attribs...>>(indices{});
+		struct mesh_setup<>
+		{
+			static std::size_t setup()
+			{
+				return 0;
+			}
+
+			static void setup_impl(int, std::size_t, std::size_t)
+			{}
+		};
+
+		template <typename Attr1, typename ... Attribs>
+		struct mesh_setup<Attr1, Attribs...>
+		{
+			static std::size_t setup()
+			{
+				std::size_t const stride = (0 + ... + attr_size<Attribs>());
+				setup_impl(0, 0, stride);
+				return stride;
+			}
+
+			static void setup_impl(int index, std::size_t offset, std::size_t stride)
+			{
+				if constexpr (std::is_same_v<Attr1, skip>)
+				{
+					mesh_setup<Attribs...>::setup_impl(index + 1, offset, stride);
+				}
+				else
+				{
+					using traits = attrib_traits<Attr1>;
+
+					gl::EnableVertexAttribArray(index);
+					gl::VertexAttribPointer(index, traits::size, traits::type, traits::normalized, stride, reinterpret_cast<char const *>(offset));
+
+					mesh_setup<Attribs...>::setup_impl(index + 1, offset + attr_size<Attr1>(), stride);
+				}
 			}
 		};
 
@@ -279,20 +233,21 @@ namespace psemek::gfx
 
 		~mesh();
 
-		template <typename Vertex>
+		template <typename ... Attribs>
 		void setup()
 		{
-			static_assert(sizeof(Vertex) == Vertex::size);
-
 			gl::BindVertexArray(array_);
 			gl::BindBuffer(gl::ARRAY_BUFFER, buffer_);
 
-			detail::mesh_setup<Vertex>::setup();
+			stride_ = detail::mesh_setup<Attribs...>::setup();
 		}
 
 		template <typename Vertex>
 		void load(std::vector<Vertex> const & vertices, GLenum usage = gl::STREAM_DRAW)
 		{
+			if (sizeof(Vertex) != stride_)
+				throw std::runtime_error("Vertex size not equal to sum of attribute sizes");
+
 			gl::BindBuffer(gl::ARRAY_BUFFER, buffer_);
 			gl::BufferData(gl::ARRAY_BUFFER, vertices.size() * sizeof(Vertex), vertices.data(), usage);
 
@@ -318,6 +273,8 @@ namespace psemek::gfx
 
 		GLsizei count_ = 0;
 
+		std::size_t stride_ = 0;
+
 		mesh(int);
 	};
 
@@ -334,13 +291,13 @@ namespace psemek::gfx
 
 		~indexed_mesh();
 
-		template <typename Vertex>
+		template <typename ... Attribs>
 		void setup()
 		{
 			gl::BindVertexArray(array_);
 			gl::BindBuffer(gl::ARRAY_BUFFER, buffer_);
 
-			detail::mesh_setup<Vertex>::setup();
+			stride_ = detail::mesh_setup<Attribs...>::setup();
 
 			gl::BindBuffer(gl::ELEMENT_ARRAY_BUFFER, index_buffer_);
 		}
@@ -348,6 +305,9 @@ namespace psemek::gfx
 		template <typename Vertex, typename Index>
 		void load(std::vector<Vertex> const & vertices, std::vector<Index> const & indices, GLenum usage = gl::STREAM_DRAW)
 		{
+			if (sizeof(Vertex) != stride_)
+				throw std::runtime_error("Vertex size not equal to sum of attribute sizes");
+
 			gl::BindBuffer(gl::ARRAY_BUFFER, buffer_);
 			gl::BufferData(gl::ARRAY_BUFFER, vertices.size() * sizeof(Vertex), vertices.data(), usage);
 			gl::BindBuffer(gl::ARRAY_BUFFER, index_buffer_);
@@ -378,6 +338,8 @@ namespace psemek::gfx
 		GLsizei count_ = 0;
 		GLenum index_type_ = 0;
 
+		std::size_t stride_ = 0;
+
 		indexed_mesh(int);
 	};
 

libs/gfx/source/gfx/fullscreen.cpp

@@ -7,15 +7,13 @@ namespace psemek::gfx
 	{
 		indexed_mesh m;
 
-		using vertex = gfx::vertex<geom::point<float, 2>>;
+		std::vector<geom::point<float, 2>> vertices(4);
-
-		std::vector<vertex> vertices(4);
 		std::vector<std::uint8_t> indices(6);
 
-		vertices[0].get<0>() = {-1.f, -1.f};
+		vertices[0] = {-1.f, -1.f};
-		vertices[1].get<0>() = { 1.f, -1.f};
+		vertices[1] = { 1.f, -1.f};
-		vertices[2].get<0>() = {-1.f,  1.f};
+		vertices[2] = {-1.f,  1.f};
-		vertices[3].get<0>() = { 1.f,  1.f};
+		vertices[3] = { 1.f,  1.f};
 
 		indices[0] = 0;
 		indices[1] = 1;
@@ -24,7 +22,7 @@ namespace psemek::gfx
 		indices[4] = 1;
 		indices[5] = 3;
 
-		m.setup<vertex>();
+		m.setup<geom::point<float, 2>>();
 		m.load(vertices, indices, gl::STATIC_DRAW);
 
 		return m;

todo.md

@@ -1,4 +1,3 @@
-* Remove gfx::vertex, setup mesh using attributes directly
 * Design affine transforms in geom & use them instead of matrices when appropriate
 * Implement pixmap font rendering
 * Create a simple generic primive painter