/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2016 by Mike Erwin.
 * All rights reserved.
 */

/** \file blender/gpu/GPU_vertex_format.h
 *  \ingroup gpu
 *
 * GPU vertex format
 */

#ifndef __GPU_VERTEX_FORMAT_H__
#define __GPU_VERTEX_FORMAT_H__

#include "GPU_common.h"

#define GPU_VERT_ATTR_MAX_LEN 16
#define GPU_VERT_ATTR_MAX_NAMES 3
#define GPU_VERT_ATTR_NAME_AVERAGE_LEN 11
#define GPU_VERT_ATTR_NAMES_BUF_LEN ((GPU_VERT_ATTR_NAME_AVERAGE_LEN + 1) * GPU_VERT_ATTR_MAX_LEN)

typedef enum {
	GPU_COMP_I8,
	GPU_COMP_U8,
	GPU_COMP_I16,
	GPU_COMP_U16,
	GPU_COMP_I32,
	GPU_COMP_U32,

	GPU_COMP_F32,

	GPU_COMP_I10
} GPUVertCompType;

typedef enum {
	GPU_FETCH_FLOAT,
	GPU_FETCH_INT,
	GPU_FETCH_INT_TO_FLOAT_UNIT, /* 127 (ubyte) -> 0.5 (and so on for other int types) */
	GPU_FETCH_INT_TO_FLOAT /* 127 (any int type) -> 127.0 */
} GPUVertFetchMode;

typedef struct GPUVertAttr {
	GPUVertFetchMode fetch_mode;
	GPUVertCompType comp_type;
	uint gl_comp_type;
	uint comp_len; /* 1 to 4 or 8 or 12 or 16 */
	uint sz; /* size in bytes, 1 to 64 */
	uint offset; /* from beginning of vertex, in bytes */
	uint name_len; /* up to GPU_VERT_ATTR_MAX_NAMES */
	const char *name[GPU_VERT_ATTR_MAX_NAMES];
} GPUVertAttr;

typedef struct GPUVertFormat {
	/** 0 to 16 (GPU_VERT_ATTR_MAX_LEN). */
	uint attr_len;
	/** Total count of active vertex attribute. */
	uint name_len;
	/** Stride in bytes, 1 to 256. */
	uint stride;
	uint name_offset;
	bool packed;
	char names[GPU_VERT_ATTR_NAMES_BUF_LEN];
	/** TODO: variable-size array */
	GPUVertAttr attrs[GPU_VERT_ATTR_MAX_LEN];
} GPUVertFormat;

struct GPUShaderInterface;

void GPU_vertformat_clear(GPUVertFormat *);
void GPU_vertformat_copy(GPUVertFormat *dest, const GPUVertFormat *src);
void GPU_vertformat_from_interface(GPUVertFormat *format, const struct GPUShaderInterface *shaderface);

uint GPU_vertformat_attr_add(
        GPUVertFormat *, const char *name,
        GPUVertCompType, uint comp_len, GPUVertFetchMode);
void GPU_vertformat_alias_add(GPUVertFormat *, const char *alias);
int GPU_vertformat_attr_id_get(const GPUVertFormat *, const char *name);

/**
 * This makes the "virtual" attributes with suffixes "0", "1", "2" to access triangle data in the vertex
 * shader.
 *
 * IMPORTANT:
 * - Call this before creating the vertex buffer and after creating all attributes
 * - Only first vertex out of 3 has the correct information. Use flat output with GL_FIRST_VERTEX_CONVENTION.
 **/
void GPU_vertformat_triple_load(GPUVertFormat *format);

/* format conversion */

typedef struct GPUPackedNormal {
	int x : 10;
	int y : 10;
	int z : 10;
	int w : 2;  /* 0 by default, can manually set to { -2, -1, 0, 1 } */
} GPUPackedNormal;

GPUPackedNormal GPU_normal_convert_i10_v3(const float data[3]);
GPUPackedNormal GPU_normal_convert_i10_s3(const short data[3]);

#endif /* __GPU_VERTEX_FORMAT_H__ */