From 9b0828ea5bb6cb4e92d6019785b3ceb88e2a58be Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 17 Apr 2023 22:43:51 +0100
Subject: Separate storing of mesh vertex/index data from configuring VAO

---
 gfx/gl/vertexArrayObject.hpp | 11 +++++++++--
 gfx/models/mesh.cpp          | 14 +++++++++++---
 gfx/models/mesh.h            |  2 ++
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/gfx/gl/vertexArrayObject.hpp b/gfx/gl/vertexArrayObject.hpp
index 3e2a18b..8c828c8 100644
--- a/gfx/gl/vertexArrayObject.hpp
+++ b/gfx/gl/vertexArrayObject.hpp
@@ -7,7 +7,7 @@
 
 class VertexArrayObject {
 public:
-	[[nodiscard]] VertexArrayObject(const GLuint arrayObject)
+	template<typename T> [[nodiscard]] VertexArrayObject(const T & arrayObject)
 	{
 		glBindVertexArray(arrayObject);
 	}
@@ -54,7 +54,13 @@ public:
 		return *this;
 	}
 
-private:
+	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)
@@ -64,6 +70,7 @@ private:
 		glBufferData(target, static_cast<GLsizeiptr>(sizeof(Value) * data.size()), data.data(), GL_STATIC_DRAW);
 	}
 
+private:
 	template<typename VertexT, typename T>
 	static void
 	set_pointer(const GLuint vertexArrayId, const void * ptr)
diff --git a/gfx/models/mesh.cpp b/gfx/models/mesh.cpp
index 4200703..2c849e7 100644
--- a/gfx/models/mesh.cpp
+++ b/gfx/models/mesh.cpp
@@ -7,10 +7,18 @@
 Mesh::Mesh(const std::span<const Vertex> vertices, const std::span<const unsigned int> indices, GLenum m) :
 	m_numIndices {static_cast<GLsizei>(indices.size())}, mode {m}
 {
-	VertexArrayObject {m_vertexArrayObject}
+	VertexArrayObject::data(vertices, m_vertexArrayBuffers[0], GL_ARRAY_BUFFER);
+	VertexArrayObject::data(indices, m_vertexArrayBuffers[1], GL_ARRAY_BUFFER);
+	configureVAO(m_vertexArrayObject);
+}
+
+VertexArrayObject &
+Mesh::configureVAO(VertexArrayObject && vao) const
+{
+	return vao
 			.addAttribs<Vertex, &Vertex::pos, &Vertex::texCoord, &Vertex::normal, &Vertex::colour, &Vertex::material>(
-					m_vertexArrayBuffers[0], vertices)
-			.addIndices(m_vertexArrayBuffers[1], indices);
+					m_vertexArrayBuffers[0])
+			.addIndices(m_vertexArrayBuffers[1]);
 }
 
 void
diff --git a/gfx/models/mesh.h b/gfx/models/mesh.h
index 25a9064..0af8d70 100644
--- a/gfx/models/mesh.h
+++ b/gfx/models/mesh.h
@@ -7,12 +7,14 @@
 #include <stdTypeDefs.hpp>
 
 class Vertex;
+class VertexArrayObject;
 
 class Mesh : public ConstTypeDefs<Mesh> {
 public:
 	Mesh(const std::span<const Vertex> vertices, const std::span<const unsigned int> indices, GLenum = GL_TRIANGLES);
 
 	void Draw() const;
+	VertexArrayObject & configureVAO(VertexArrayObject &&) const;
 
 private:
 	glVertexArray m_vertexArrayObject;
-- 
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