// Gawain element list (AKA index buffer)
//
// This code is part of the Gawain library, with modifications
// specific to integration with Blender.
//
// Copyright 2016 Mike Erwin
//
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of
// the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.

#pragma once

#include "common.h"

#define TRACK_INDEX_RANGE 1

typedef enum {
	INDEX_U8 = GL_UNSIGNED_BYTE, // GL has this, Vulkan does not
	INDEX_U16 = GL_UNSIGNED_SHORT,
	INDEX_U32 = GL_UNSIGNED_INT
} IndexType;

typedef struct {
	unsigned index_ct;
#if TRACK_INDEX_RANGE
	IndexType index_type;
	unsigned min_index;
	unsigned max_index;
	unsigned base_index;
#endif
	void* data; // NULL indicates data in VRAM (unmapped) or not yet allocated
	GLuint vbo_id; // 0 indicates not yet sent to VRAM
} ElementList;

void ElementList_use(ElementList*);
unsigned ElementList_size(const ElementList*);

typedef struct {
	unsigned max_allowed_index;
	unsigned max_index_ct;
	unsigned index_ct;
	PrimitiveType prim_type;
	unsigned* data;
} ElementListBuilder;

// supported primitives:
//  PRIM_POINTS
//  PRIM_LINES
//  PRIM_TRIANGLES

void ElementListBuilder_init(ElementListBuilder*, PrimitiveType, unsigned prim_ct, unsigned vertex_ct);
//void ElementListBuilder_init_custom(ElementListBuilder*, PrimitiveType, unsigned index_ct, unsigned vertex_ct);

void add_generic_vertex(ElementListBuilder*, unsigned v);

void add_point_vertex(ElementListBuilder*, unsigned v);
void add_line_vertices(ElementListBuilder*, unsigned v1, unsigned v2);
void add_triangle_vertices(ElementListBuilder*, unsigned v1, unsigned v2, unsigned v3);

ElementList* ElementList_build(ElementListBuilder*);
void ElementList_build_in_place(ElementListBuilder*, ElementList*);

void ElementList_discard(ElementList*);