1 files changed, 162 insertions, 0 deletions
diff --git a/gfx/gl/glVertexArray.h b/gfx/gl/glVertexArray.h
new file mode 100644
index 0000000..4e8113f
--- /dev/null
+++ b/gfx/gl/glVertexArray.h
@@ -0,0 +1,162 @@
+#pragma once
+
+#include "collections.h"
+#include "glArrays.h"
+#include "glBuffer.h"
+#include "gl_traits.h"
+#include "util.h"
+
+namespace Impl {
+	class VertexArrayConfigurator {
+	public:
+		template<typename M, typename T> struct MP {
+			constexpr MP(M T::* ptr) : ptr {ptr} { }
+
+			constexpr
+			operator GLuint() const
+			{
+				constexpr static char dummy {};
+				return static_cast<GLuint>(reinterpret_cast<const char *>(&(reinterpret_cast<const T *>(&dummy)->*ptr))
+						- reinterpret_cast<const char *>(&dummy));
+			}
+
+			M T::* ptr;
+		};
+
+		explicit VertexArrayConfigurator(GLuint name) : name {name} { }
+
+		VertexArrayConfigurator &
+		addIndices(const glBuffer & buffer)
+		{
+			glVertexArrayElementBuffer(name, buffer);
+			return *this;
+		}
+
+		VertexArrayConfigurator &
+		addIndices(glBuffer & buffer, const SequentialCollection<GLuint> auto & indices)
+		{
+			buffer.storage(indices, 0);
+			return addIndices(buffer);
+		}
+
+		// Customisation point
+		template<typename VertexT> VertexArrayConfigurator & addAttribsFor(GLuint divisor);
+
+		template<typename VertexT>
+		VertexArrayConfigurator &
+		addAttribsFor(GLuint divisor, const glBuffer & buffer)
+		{
+			glVertexArrayVertexBuffer(name, binding, buffer, 0, sizeof(VertexT));
+			return addAttribsFor<VertexT>(divisor);
+		}
+
+		template<typename VertexT, auto... Attribs>
+		VertexArrayConfigurator &
+		addAttribs(const GLuint divisor)
+		{
+			configureAttribs<VertexT, Attribs...>(divisor);
+			return *this;
+		}
+
+		template<typename VertexT, auto... Attribs>
+		VertexArrayConfigurator &
+		addAttribs(const GLuint divisor, const glBuffer & buffer)
+		{
+			glVertexArrayVertexBuffer(name, binding, buffer, 0, sizeof(VertexT));
+			return addAttribs<VertexT, Attribs...>(divisor);
+		}
+
+		template<typename VertexT, auto... Attribs>
+		VertexArrayConfigurator &
+		addAttribs(const GLuint divisor, glBuffer & buffer, const SequentialCollection<VertexT> auto & data)
+		{
+			buffer.storage(data, 0);
+			return addAttribs<VertexT, Attribs...>(divisor, buffer);
+		}
+
+	private:
+		void
+		setPointerMeta(const GLuint usedAttribs)
+		{
+			while (attrib < usedAttribs) {
+				glEnableVertexArrayAttrib(name, attrib);
+				glVertexArrayAttribBinding(name, attrib++, binding);
+			}
+		}
+
+		template<typename T>
+		void
+		setPointer(const GLuint offset)
+		{
+			setPointerMeta(attrib + gl_traits<T>::vertexArrayAttribFormat(name, attrib, offset));
+		}
+
+		template<typename VertexT, auto Attrib>
+		void
+		setPointer()
+		{
+			using Mbr = MemberValueType<Attrib>;
+			setPointer<Mbr>(MP<Mbr, VertexT> {Attrib});
+		}
+
+		template<typename VertexT, auto... Attribs>
+		void
+		configureAttribs(const GLuint divisor)
+		{
+			if constexpr (sizeof...(Attribs) == 0) {
+				setPointer<VertexT>(0);
+			}
+			else {
+				((setPointer<VertexT, Attribs>()), ...);
+			}
+			glVertexArrayBindingDivisor(name, binding++, divisor);
+		}
+
+		GLuint name;
+		GLuint binding = 0;
+		GLuint attrib = 0;
+	};
+
+	struct glVertexArray : Detail::glNamed {
+		VertexArrayConfigurator
+		configure()
+		{
+			return VertexArrayConfigurator {name};
+		}
+
+		template<typename glAllocated>
+		void
+		useBuffer(GLuint binding, const glAllocated & buffer, GLsizei offset = 0) const
+			requires requires {
+				{ buffer.bufferName() } -> std::same_as<GLuint>;
+			}
+		{
+			using T = typename glAllocated::value_type;
+			useBuffer(binding, buffer.bufferName(), sizeof(T), offset);
+		}
+
+		template<typename V>
+		void
+		useBuffer(GLuint binding, GLuint bufferName, auto V::* mbr) const
+		{
+			useBuffer(binding, bufferName, sizeof(V), VertexArrayConfigurator::MP {mbr});
+		}
+
+		template<typename V>
+		void
+		useBuffer(GLuint binding, GLuint bufferName, GLintptr offset = 0) const
+		{
+			useBuffer(binding, bufferName, sizeof(V), offset);
+		}
+
+		void
+		useBuffer(GLuint binding, GLuint bufferName, GLsizei stride, GLintptr offset = 0) const
+		{
+			glVertexArrayVertexBuffer(name, binding, bufferName, offset, stride);
+		}
+	};
+}
+
+template<size_t N>
+using glVertexArrays = glManagedArray<Impl::glVertexArray, N, &glCreateVertexArrays, &glDeleteVertexArrays>;
+using glVertexArray = glManagedSingle<Impl::glVertexArray, &glCreateVertexArrays, &glDeleteVertexArrays>;