Vertex vertex(V3 pos)
{
	Vertex v = { pos };
	return v;
}

void mesh_init_buffers(Mesh *mesh)
{
	Assert(mesh->verts);
	Assert(mesh->nverts > 0);
	
	glGenVertexArrays(1, &mesh->vao);
	glBindVertexArray(mesh->vao);

	glGenBuffers(1, &mesh->vbo);
	glBindBuffer(GL_ARRAY_BUFFER, mesh->vbo);
	glBufferData(GL_ARRAY_BUFFER, mesh->nverts*sizeof(Vertex), mesh->verts, GL_STATIC_DRAW);

	if (mesh->indices && (mesh->nindices > 0)) {
		glGenBuffers(1, &mesh->ebo);
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mesh->ebo);
		glBufferData(GL_ELEMENT_ARRAY_BUFFER, mesh->nindices*sizeof(U32), mesh->indices, GL_STATIC_DRAW);
	}

	glEnableVertexAttribArray(PRGE_SHADER_POS_LOC);
	glVertexAttribPointer(PRGE_SHADER_POS_LOC, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0);
	glBindVertexArray(0);
}

Mesh *mesh(Arena *arena, Vertex *verts, U32 nverts, U32 *indices, U32 nindices)
{
	Mesh *mesh = arena_push(arena, sizeof(Mesh));
	mesh->verts = verts;
	mesh->nverts = nverts;
	mesh->indices = indices;
	mesh->nindices = nindices;
	mesh_init_buffers(mesh);
	return mesh;
}

void mesh_clear(Mesh *mesh)
{
	glBindVertexArray(mesh->vao);
	glDisableVertexAttribArray(PRGE_SHADER_POS_LOC);

	glBindVertexArray(0);
	glDeleteVertexArrays(1, &mesh->vao);
	
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glDeleteBuffers(1, &mesh->vbo);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	glDeleteBuffers(1, &mesh->ebo);
}

void mesh_draw(Mesh mesh)
{
	Assert(mesh.vao);
	glBindVertexArray(mesh.vao);
	if (mesh.ebo)
		glDrawElements(GL_TRIANGLES, mesh.nindices, GL_UNSIGNED_INT, 0);
	else
		glDrawArrays(GL_TRIANGLES, 0, mesh.nverts);
	glBindVertexArray(0);
}