1 files changed, 109 insertions, 0 deletions
diff --git a/gfx/gl/vertexArrayObject.h b/gfx/gl/vertexArrayObject.h
new file mode 100644
index 0000000..085cba6
--- /dev/null
+++ b/gfx/gl/vertexArrayObject.h
@@ -0,0 +1,109 @@
+#pragma once
+
+#include "collections.h"
+#include "gl_traits.h"
+#include "special_members.h"
+#include <GL/glew.h>
+
+class VertexArrayObject {
+public:
+	template<typename T> [[nodiscard]] VertexArrayObject(const T & arrayObject)
+	{
+		glBindVertexArray(arrayObject);
+	}
+	~VertexArrayObject()
+	{
+		glBindVertexArray(0);
+	}
+	NO_MOVE(VertexArrayObject);
+	NO_COPY(VertexArrayObject);
+
+	template<typename m, typename T> struct MP {
+		constexpr MP(m T::*p) : P {p} { }
+		operator void *() const
+		{
+			return &(static_cast<T *>(nullptr)->*P);
+		}
+		m T::*P;
+		using value_type = m;
+	};
+	template<typename m, typename T> MP(m T::*) -> MP<m, T>;
+
+	template<typename VertexT, MP... attribs>
+	VertexArrayObject &
+	addAttribs(const GLuint arrayBuffer, const SequentialCollection<VertexT> auto & vertices, const GLuint divisor = 0)
+	{
+		addAttribs<VertexT, attribs...>(arrayBuffer, divisor);
+		data(vertices, arrayBuffer, GL_ARRAY_BUFFER);
+		return *this;
+	}
+
+	template<typename VertexT, MP... attribs>
+	VertexArrayObject &
+	addAttribs(const GLuint arrayBuffer, const GLuint divisor = 0)
+	{
+		configure_attribs<VertexT, attribs...>(arrayBuffer, divisor);
+		return *this;
+	}
+
+	template<typename Indices>
+	VertexArrayObject &
+	addIndices(const GLuint arrayBuffer, const Indices & indices)
+	{
+		data(indices, arrayBuffer, GL_ELEMENT_ARRAY_BUFFER);
+		return *this;
+	}
+
+	VertexArrayObject &
+	addIndices(const GLuint arrayBuffer)
+	{
+		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, arrayBuffer);
+		return *this;
+	}
+
+	template<typename Data>
+	static void
+	data(const Data & data, const GLuint arrayBuffer, GLenum target)
+	{
+		using Value = typename Data::value_type;
+		glBindBuffer(target, arrayBuffer);
+		glBufferData(target, static_cast<GLsizeiptr>(sizeof(Value) * data.size()), data.data(), GL_STATIC_DRAW);
+	}
+
+private:
+	template<typename VertexT, typename T>
+	static auto
+	set_pointer(const GLuint vertexArrayId, const void * ptr, const GLuint divisor)
+	{
+		using traits = gl_traits<T>;
+		const auto usedAttribs
+				= traits::vertexAttribFunc(vertexArrayId, traits::size, traits::type, sizeof(VertexT), ptr);
+		for (GLuint i {}; i < usedAttribs; i++) {
+			glEnableVertexAttribArray(vertexArrayId + i);
+			glVertexAttribDivisor(vertexArrayId + i, divisor);
+		}
+		return usedAttribs;
+	}
+
+	template<typename VertexT, MP attrib>
+	static auto
+	set_pointer(const GLuint vertexArrayId, const GLuint divisor)
+	{
+		return set_pointer<VertexT, typename decltype(attrib)::value_type>(vertexArrayId, attrib, divisor);
+	}
+
+	template<typename VertexT, MP... attribs>
+	void
+	configure_attribs(const GLuint arrayBuffer, const GLuint divisor)
+	{
+		glBindBuffer(GL_ARRAY_BUFFER, arrayBuffer);
+		if constexpr (sizeof...(attribs) == 0) {
+			vertexArrayId += set_pointer<VertexT, VertexT>(vertexArrayId, nullptr, divisor);
+		}
+		else {
+			((vertexArrayId += set_pointer<VertexT, attribs>(vertexArrayId, divisor)), ...);
+		}
+	}
+
+	GLuint vertexArrayId {};
+};