/******************************************************************************
    Copyright (C) 2013 by Hugh Bailey <obs.jim@gmail.com>

    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, see <http://www.gnu.org/licenses/>.
******************************************************************************/

#pragma once

#include "../util/bmem.h"
#include "input.h"
#ifdef __APPLE__
#include <objc/objc-runtime.h>
#endif

/*
 * This is an API-independent graphics subsystem wrapper.
 *
 *   This allows the use of OpenGL and different Direct3D versions through
 * one shared interface.
 */

#ifdef __cplusplus
extern "C" {
#endif

#define GS_MAX_TEXTURES 8

struct vec2;
struct vec3;
struct vec4;
struct quat;
struct axisang;
struct plane;
struct matrix3;
struct matrix4;

enum gs_draw_mode {
	GS_POINTS,
	GS_LINES,
	GS_LINESTRIP,
	GS_TRIS,
	GS_TRISTRIP
};

enum gs_color_format {
	GS_UNKNOWN,
	GS_A8,
	GS_R8,
	GS_RGBA,
	GS_BGRX,
	GS_BGRA,
	GS_R10G10B10A2,
	GS_RGBA16,
	GS_R16,
	GS_RGBA16F,
	GS_RGBA32F,
	GS_RG16F,
	GS_RG32F,
	GS_R16F,
	GS_R32F,
	GS_DXT1,
	GS_DXT3,
	GS_DXT5
};

enum gs_zstencil_format {
	GS_ZS_NONE,
	GS_Z16,
	GS_Z24_S8,
	GS_Z32F,
	GS_Z32F_S8X24
};

enum gs_index_type {
	GS_UNSIGNED_SHORT,
	GS_UNSIGNED_LONG
};

enum gs_cull_mode {
	GS_BACK,
	GS_FRONT,
	GS_NEITHER
};

enum gs_blend_type {
	GS_BLEND_ZERO,
	GS_BLEND_ONE,
	GS_BLEND_SRCCOLOR,
	GS_BLEND_INVSRCCOLOR,
	GS_BLEND_SRCALPHA,
	GS_BLEND_INVSRCALPHA,
	GS_BLEND_DSTCOLOR,
	GS_BLEND_INVDSTCOLOR,
	GS_BLEND_DSTALPHA,
	GS_BLEND_INVDSTALPHA,
	GS_BLEND_SRCALPHASAT
};

enum gs_depth_test {
	GS_NEVER,
	GS_LESS,
	GS_LEQUAL,
	GS_EQUAL,
	GS_GEQUAL,
	GS_GREATER,
	GS_NOTEQUAL,
	GS_ALWAYS
};

enum gs_stencil_side {
	GS_STENCIL_FRONT=1,
	GS_STENCIL_BACK,
	GS_STENCIL_BOTH
};

enum gs_stencil_op_type {
	GS_KEEP,
	GS_ZERO,
	GS_REPLACE,
	GS_INCR,
	GS_DECR,
	GS_INVERT
};

enum gs_cube_sides {
	GS_POSITIVE_X,
	GS_NEGATIVE_X,
	GS_POSITIVE_Y,
	GS_NEGATIVE_Y,
	GS_POSITIVE_Z,
	GS_NEGATIVE_Z
};

enum gs_sample_filter {
	GS_FILTER_POINT,
	GS_FILTER_LINEAR,
	GS_FILTER_ANISOTROPIC,
	GS_FILTER_MIN_MAG_POINT_MIP_LINEAR,
	GS_FILTER_MIN_POINT_MAG_LINEAR_MIP_POINT,
	GS_FILTER_MIN_POINT_MAG_MIP_LINEAR,
	GS_FILTER_MIN_LINEAR_MAG_MIP_POINT,
	GS_FILTER_MIN_LINEAR_MAG_POINT_MIP_LINEAR,
	GS_FILTER_MIN_MAG_LINEAR_MIP_POINT,
};

enum gs_address_mode {
	GS_ADDRESS_CLAMP,
	GS_ADDRESS_WRAP,
	GS_ADDRESS_MIRROR,
	GS_ADDRESS_BORDER,
	GS_ADDRESS_MIRRORONCE
};

enum gs_texture_type {
	GS_TEXTURE_2D,
	GS_TEXTURE_3D,
	GS_TEXTURE_CUBE
};

struct gs_monitor_info {
	int rotation_degrees;
	long x;
	long y;
	long cx;
	long cy;
};

struct gs_tvertarray {
	size_t width;
	void *array;
};

struct gs_vb_data {
	size_t num;
	struct vec3 *points;
	struct vec3 *normals;
	struct vec3 *tangents;
	uint32_t *colors;

	size_t num_tex;
	struct gs_tvertarray *tvarray;
};

static inline struct gs_vb_data *gs_vbdata_create(void)
{
	return (struct gs_vb_data*)bzalloc(sizeof(struct gs_vb_data));
}

static inline void gs_vbdata_destroy(struct gs_vb_data *data)
{
	uint32_t i;
	if (!data)
		return;

	bfree(data->points);
	bfree(data->normals);
	bfree(data->tangents);
	bfree(data->colors);
	for (i = 0; i < data->num_tex; i++)
		bfree(data->tvarray[i].array);
	bfree(data->tvarray);
	bfree(data);
}

struct gs_sampler_info {
	enum gs_sample_filter filter;
	enum gs_address_mode address_u;
	enum gs_address_mode address_v;
	enum gs_address_mode address_w;
	int max_anisotropy;
	uint32_t border_color;
};

struct gs_display_mode {
	uint32_t width;
	uint32_t height;
	uint32_t bits;
	uint32_t freq;
};

struct gs_rect {
	int x;
	int y;
	int cx;
	int cy;
};

/* wrapped opaque data types */

struct gs_texture;
struct gs_stage_surface;
struct gs_zstencil_buffer;
struct gs_vertex_buffer;
struct gs_index_buffer;
struct gs_sampler_state;
struct gs_shader;
struct gs_swap_chain;
struct gs_texrender;
struct gs_shader_param;
struct gs_effect;
struct gs_effect_technique;
struct gs_effect_pass;
struct gs_effect_param;
struct gs_device;
struct graphics_subsystem;

typedef struct gs_texture          gs_texture_t;
typedef struct gs_stage_surface    gs_stagesurf_t;
typedef struct gs_zstencil_buffer  gs_zstencil_t;
typedef struct gs_vertex_buffer    gs_vertbuffer_t;
typedef struct gs_index_buffer     gs_indexbuffer_t;
typedef struct gs_sampler_state    gs_samplerstate_t;
typedef struct gs_swap_chain       gs_swapchain_t;
typedef struct gs_texture_render   gs_texrender_t;
typedef struct gs_shader           gs_shader_t;
typedef struct gs_shader_param     gs_sparam_t;
typedef struct gs_effect           gs_effect_t;
typedef struct gs_effect_technique gs_technique_t;
typedef struct gs_effect_param     gs_eparam_t;
typedef struct gs_device           gs_device_t;
typedef struct graphics_subsystem  graphics_t;

/* ---------------------------------------------------
 * shader functions
 * --------------------------------------------------- */

enum gs_shader_param_type {
	GS_SHADER_PARAM_UNKNOWN,
	GS_SHADER_PARAM_BOOL,
	GS_SHADER_PARAM_FLOAT,
	GS_SHADER_PARAM_INT,
	GS_SHADER_PARAM_STRING,
	GS_SHADER_PARAM_VEC2,
	GS_SHADER_PARAM_VEC3,
	GS_SHADER_PARAM_VEC4,
	GS_SHADER_PARAM_INT2,
	GS_SHADER_PARAM_INT3,
	GS_SHADER_PARAM_INT4,
	GS_SHADER_PARAM_MATRIX4X4,
	GS_SHADER_PARAM_TEXTURE,
};

struct gs_shader_param_info {
	enum gs_shader_param_type type;
	const char *name;
};

enum gs_shader_type {
	GS_SHADER_VERTEX,
	GS_SHADER_PIXEL,
};

EXPORT void gs_shader_destroy(gs_shader_t *shader);

EXPORT int gs_shader_get_num_params(const gs_shader_t *shader);
EXPORT gs_sparam_t *gs_shader_get_param_by_idx(gs_shader_t *shader,
		uint32_t param);
EXPORT gs_sparam_t *gs_shader_get_param_by_name(gs_shader_t *shader,
		const char *name);

EXPORT gs_sparam_t *gs_shader_get_viewproj_matrix(const gs_shader_t *shader);
EXPORT gs_sparam_t *gs_shader_get_world_matrix(const gs_shader_t *shader);

EXPORT void gs_shader_get_param_info(const gs_sparam_t *param,
		struct gs_shader_param_info *info);
EXPORT void gs_shader_set_bool(gs_sparam_t *param, bool val);
EXPORT void gs_shader_set_float(gs_sparam_t *param, float val);
EXPORT void gs_shader_set_int(gs_sparam_t *param, int val);
EXPORT void gs_shader_set_matrix3(gs_sparam_t *param, const struct matrix3 *val);
EXPORT void gs_shader_set_matrix4(gs_sparam_t *param, const struct matrix4 *val);
EXPORT void gs_shader_set_vec2(gs_sparam_t *param, const struct vec2 *val);
EXPORT void gs_shader_set_vec3(gs_sparam_t *param, const struct vec3 *val);
EXPORT void gs_shader_set_vec4(gs_sparam_t *param, const struct vec4 *val);
EXPORT void gs_shader_set_texture(gs_sparam_t *param, gs_texture_t *val);
EXPORT void gs_shader_set_val(gs_sparam_t *param, const void *val, size_t size);
EXPORT void gs_shader_set_default(gs_sparam_t *param);
EXPORT void gs_shader_set_next_sampler(gs_sparam_t *param,
		gs_samplerstate_t *sampler);

/* ---------------------------------------------------
 * effect functions
 * --------------------------------------------------- */

/*enum gs_effect_property_type {
	GS_EFFECT_NONE,
	GS_EFFECT_BOOL,
	GS_EFFECT_FLOAT,
	GS_EFFECT_COLOR,
	GS_EFFECT_TEXTURE
};*/

struct gs_effect_param_info {
	const char *name;
	enum gs_shader_param_type type;

	/* const char *full_name;
	enum gs_effect_property_type prop_type;

	float min, max, inc, mul; */
};

EXPORT void gs_effect_destroy(gs_effect_t *effect);

EXPORT gs_technique_t *gs_effect_get_technique(const gs_effect_t *effect,
		const char *name);

EXPORT gs_technique_t *gs_effect_get_current_technique(
		const gs_effect_t *effect);

EXPORT size_t gs_technique_begin(gs_technique_t *technique);
EXPORT void gs_technique_end(gs_technique_t *technique);
EXPORT bool gs_technique_begin_pass(gs_technique_t *technique, size_t pass);
EXPORT bool gs_technique_begin_pass_by_name(gs_technique_t *technique,
		const char *name);
EXPORT void gs_technique_end_pass(gs_technique_t *technique);

EXPORT size_t gs_effect_get_num_params(const gs_effect_t *effect);
EXPORT gs_eparam_t *gs_effect_get_param_by_idx(const gs_effect_t *effect,
		size_t param);
EXPORT gs_eparam_t *gs_effect_get_param_by_name(const gs_effect_t *effect,
		const char *name);

/** Helper function to simplify effect usage.  Use with a while loop that
 * contains drawing functions.  Automatically handles techniques, passes, and
 * unloading. */
EXPORT bool gs_effect_loop(gs_effect_t *effect, const char *name);

/** used internally */
EXPORT void gs_effect_update_params(gs_effect_t *effect);

EXPORT gs_eparam_t *gs_effect_get_viewproj_matrix(const gs_effect_t *effect);
EXPORT gs_eparam_t *gs_effect_get_world_matrix(const gs_effect_t *effect);

EXPORT void gs_effect_get_param_info(const gs_eparam_t *param,
		struct gs_effect_param_info *info);
EXPORT void gs_effect_set_bool(gs_eparam_t *param, bool val);
EXPORT void gs_effect_set_float(gs_eparam_t *param, float val);
EXPORT void gs_effect_set_int(gs_eparam_t *param, int val);
EXPORT void gs_effect_set_matrix4(gs_eparam_t *param,
		const struct matrix4 *val);
EXPORT void gs_effect_set_vec2(gs_eparam_t *param, const struct vec2 *val);
EXPORT void gs_effect_set_vec3(gs_eparam_t *param, const struct vec3 *val);
EXPORT void gs_effect_set_vec4(gs_eparam_t *param, const struct vec4 *val);
EXPORT void gs_effect_set_texture(gs_eparam_t *param, gs_texture_t *val);
EXPORT void gs_effect_set_val(gs_eparam_t *param, const void *val, size_t size);
EXPORT void gs_effect_set_default(gs_eparam_t *param);
EXPORT void gs_effect_set_next_sampler(gs_eparam_t *param,
		gs_samplerstate_t *sampler);

/* ---------------------------------------------------
 * texture render helper functions
 * --------------------------------------------------- */

EXPORT gs_texrender_t *gs_texrender_create(enum gs_color_format format,
		enum gs_zstencil_format zsformat);
EXPORT void gs_texrender_destroy(gs_texrender_t *texrender);
EXPORT bool gs_texrender_begin(gs_texrender_t *texrender, uint32_t cx,
		uint32_t cy);
EXPORT void gs_texrender_end(gs_texrender_t *texrender);
EXPORT void gs_texrender_reset(gs_texrender_t *texrender);
EXPORT gs_texture_t *gs_texrender_get_texture(const gs_texrender_t *texrender);

/* ---------------------------------------------------
 * graphics subsystem
 * --------------------------------------------------- */

#define GS_BUILD_MIPMAPS (1<<0)
#define GS_DYNAMIC       (1<<1)
#define GS_RENDER_TARGET (1<<2)
#define GS_GL_DUMMYTEX   (1<<3) /**<< texture with no allocated texture data */

/* ---------------- */
/* global functions */

#define GS_SUCCESS                 0
#define GS_ERROR_FAIL             -1
#define GS_ERROR_MODULE_NOT_FOUND -2
#define GS_ERROR_NOT_SUPPORTED    -3

struct gs_window {
#if defined(_WIN32)
	void                    *hwnd;
#elif defined(__APPLE__)
	__unsafe_unretained id  view;
#elif defined(__linux__) || defined(__FreeBSD__)
	/* I'm not sure how portable defining id to uint32_t is. */
	uint32_t id;
	void* display;
#endif
};

struct gs_init_data {
	struct gs_window        window;
	uint32_t                cx, cy;
	uint32_t                num_backbuffers;
	enum gs_color_format    format;
	enum gs_zstencil_format zsformat;
	uint32_t                adapter;
};

#define GS_DEVICE_OPENGL      1
#define GS_DEVICE_DIRECT3D_11 2

EXPORT const char *gs_get_device_name(void);
EXPORT int gs_get_device_type(void);
EXPORT void gs_enum_adapters(
		bool (*callback)(void *param, const char *name, uint32_t id),
		void *param);

EXPORT int gs_create(graphics_t **graphics, const char *module,
		uint32_t adapter);
EXPORT void gs_destroy(graphics_t *graphics);

EXPORT void gs_enter_context(graphics_t *graphics);
EXPORT void gs_leave_context(void);
EXPORT graphics_t *gs_get_context(void);

EXPORT void gs_matrix_push(void);
EXPORT void gs_matrix_pop(void);
EXPORT void gs_matrix_identity(void);
EXPORT void gs_matrix_transpose(void);
EXPORT void gs_matrix_set(const struct matrix4 *matrix);
EXPORT void gs_matrix_get(struct matrix4 *dst);
EXPORT void gs_matrix_mul(const struct matrix4 *matrix);
EXPORT void gs_matrix_rotquat(const struct quat *rot);
EXPORT void gs_matrix_rotaa(const struct axisang *rot);
EXPORT void gs_matrix_translate(const struct vec3 *pos);
EXPORT void gs_matrix_scale(const struct vec3 *scale);
EXPORT void gs_matrix_rotaa4f(float x, float y, float z, float angle);
EXPORT void gs_matrix_translate3f(float x, float y, float z);
EXPORT void gs_matrix_scale3f(float x, float y, float z);

EXPORT void gs_render_start(bool b_new);
EXPORT void gs_render_stop(enum gs_draw_mode mode);
EXPORT gs_vertbuffer_t *gs_render_save(void);
EXPORT void gs_vertex2f(float x, float y);
EXPORT void gs_vertex3f(float x, float y, float z);
EXPORT void gs_normal3f(float x, float y, float z);
EXPORT void gs_color(uint32_t color);
EXPORT void gs_texcoord(float x, float y, int unit);
EXPORT void gs_vertex2v(const struct vec2 *v);
EXPORT void gs_vertex3v(const struct vec3 *v);
EXPORT void gs_normal3v(const struct vec3 *v);
EXPORT void gs_color4v(const struct vec4 *v);
EXPORT void gs_texcoord2v(const struct vec2 *v, int unit);

EXPORT input_t *gs_get_input(void);
EXPORT gs_effect_t *gs_get_effect(void);

EXPORT gs_effect_t *gs_effect_create_from_file(const char *file,
		char **error_string);
EXPORT gs_effect_t *gs_effect_create(const char *effect_string,
		const char *filename, char **error_string);

EXPORT gs_shader_t *gs_vertexshader_create_from_file(const char *file,
		char **error_string);
EXPORT gs_shader_t *gs_pixelshader_create_from_file(const char *file,
		char **error_string);

EXPORT gs_texture_t *gs_texture_create_from_file(const char *file);
EXPORT uint8_t *gs_create_texture_file_data(const char *file,
		enum gs_color_format *format, uint32_t *cx, uint32_t *cy);

#define GS_FLIP_U (1<<0)
#define GS_FLIP_V (1<<1)

/**
 * Draws a 2D sprite
 *
 *   If width or height is 0, the width or height of the texture will be used.
 * The flip value specifies whether the texture should be flipped on the U or V
 * axis with GS_FLIP_U and GS_FLIP_V.
 */
EXPORT void gs_draw_sprite(gs_texture_t *tex, uint32_t flip, uint32_t width,
		uint32_t height);

EXPORT void gs_draw_sprite_subregion(gs_texture_t *tex, uint32_t flip,
		uint32_t x, uint32_t y, uint32_t cx, uint32_t cy);

EXPORT void gs_draw_cube_backdrop(gs_texture_t *cubetex, const struct quat *rot,
		float left, float right, float top, float bottom, float znear);

/** sets the viewport to current swap chain size */
EXPORT void gs_reset_viewport(void);

/** sets default screen-sized orthographic mode */
EXPORT void gs_set_2d_mode(void);
/** sets default screen-sized perspective mode */
EXPORT void gs_set_3d_mode(double fovy, double znear, double zvar);

EXPORT void gs_viewport_push(void);
EXPORT void gs_viewport_pop(void);

EXPORT void gs_texture_set_image(gs_texture_t *tex, const uint8_t *data,
		uint32_t linesize, bool invert);
EXPORT void gs_cubetexture_set_image(gs_texture_t *cubetex, uint32_t side,
		const void *data, uint32_t linesize, bool invert);

EXPORT void gs_perspective(float fovy, float aspect, float znear, float zfar);

EXPORT void gs_blend_state_push(void);
EXPORT void gs_blend_state_pop(void);
EXPORT void gs_reset_blend_state(void);

/* -------------------------- */
/* library-specific functions */

EXPORT gs_swapchain_t *gs_swapchain_create(const struct gs_init_data *data);

EXPORT void gs_resize(uint32_t x, uint32_t y);
EXPORT void gs_get_size(uint32_t *x, uint32_t *y);
EXPORT uint32_t gs_get_width(void);
EXPORT uint32_t gs_get_height(void);

EXPORT gs_texture_t *gs_texture_create(uint32_t width, uint32_t height,
		enum gs_color_format color_format, uint32_t levels,
		const uint8_t **data, uint32_t flags);
EXPORT gs_texture_t *gs_cubetexture_create(uint32_t size,
		enum gs_color_format color_format, uint32_t levels,
		const uint8_t **data, uint32_t flags);
EXPORT gs_texture_t *gs_voltexture_create(uint32_t width, uint32_t height,
		uint32_t depth, enum gs_color_format color_format,
		uint32_t levels, const uint8_t **data, uint32_t flags);

EXPORT gs_zstencil_t *gs_zstencil_create(uint32_t width, uint32_t height,
		enum gs_zstencil_format format);

EXPORT gs_stagesurf_t *gs_stagesurface_create(uint32_t width, uint32_t height,
		enum gs_color_format color_format);

EXPORT gs_samplerstate_t *gs_samplerstate_create(
		const struct gs_sampler_info *info);

EXPORT gs_shader_t *gs_vertexshader_create(const char *shader,
		const char *file, char **error_string);
EXPORT gs_shader_t *gs_pixelshader_create(const char *shader,
		const char *file, char **error_string);

EXPORT gs_vertbuffer_t *gs_vertexbuffer_create(struct gs_vb_data *data,
		uint32_t flags);
EXPORT gs_indexbuffer_t *gs_indexbuffer_create(enum gs_index_type type,
		void *indices, size_t num, uint32_t flags);

EXPORT enum gs_texture_type gs_get_texture_type(const gs_texture_t *texture);

EXPORT void gs_load_vertexbuffer(gs_vertbuffer_t *vertbuffer);
EXPORT void gs_load_indexbuffer(gs_indexbuffer_t *indexbuffer);
EXPORT void gs_load_texture(gs_texture_t *tex, int unit);
EXPORT void gs_load_samplerstate(gs_samplerstate_t *samplerstate, int unit);
EXPORT void gs_load_vertexshader(gs_shader_t *vertshader);
EXPORT void gs_load_pixelshader(gs_shader_t *pixelshader);

EXPORT void gs_load_default_samplerstate(bool b_3d, int unit);

EXPORT gs_shader_t *gs_get_vertex_shader(void);
EXPORT gs_shader_t *gs_get_pixel_shader(void);

EXPORT gs_texture_t  *gs_get_render_target(void);
EXPORT gs_zstencil_t *gs_get_zstencil_target(void);

EXPORT void gs_set_render_target(gs_texture_t *tex, gs_zstencil_t *zstencil);
EXPORT void gs_set_cube_render_target(gs_texture_t *cubetex, int side,
		gs_zstencil_t *zstencil);

EXPORT void gs_copy_texture(gs_texture_t *dst, gs_texture_t *src);
EXPORT void gs_copy_texture_region(
		gs_texture_t *dst, uint32_t dst_x, uint32_t dst_y,
		gs_texture_t *src, uint32_t src_x, uint32_t src_y,
		uint32_t src_w, uint32_t src_h);
EXPORT void gs_stage_texture(gs_stagesurf_t *dst, gs_texture_t *src);

EXPORT void gs_begin_scene(void);
EXPORT void gs_draw(enum gs_draw_mode draw_mode, uint32_t start_vert,
		uint32_t num_verts);
EXPORT void gs_end_scene(void);

#define GS_CLEAR_COLOR   (1<<0)
#define GS_CLEAR_DEPTH   (1<<1)
#define GS_CLEAR_STENCIL (1<<2)

EXPORT void gs_load_swapchain(gs_swapchain_t *swapchain);
EXPORT void gs_clear(uint32_t clear_flags, const struct vec4 *color,
		float depth, uint8_t stencil);
EXPORT void gs_present(void);
EXPORT void gs_flush(void);

EXPORT void gs_set_cull_mode(enum gs_cull_mode mode);
EXPORT enum gs_cull_mode gs_get_cull_mode(void);

EXPORT void gs_enable_blending(bool enable);
EXPORT void gs_enable_depth_test(bool enable);
EXPORT void gs_enable_stencil_test(bool enable);
EXPORT void gs_enable_stencil_write(bool enable);
EXPORT void gs_enable_color(bool red, bool green, bool blue, bool alpha);

EXPORT void gs_blend_function(enum gs_blend_type src, enum gs_blend_type dest);
EXPORT void gs_blend_function_separate(
		enum gs_blend_type src_c, enum gs_blend_type dest_c,
		enum gs_blend_type src_a, enum gs_blend_type dest_a);
EXPORT void gs_depth_function(enum gs_depth_test test);

EXPORT void gs_stencil_function(enum gs_stencil_side side,
		enum gs_depth_test test);
EXPORT void gs_stencil_op(enum gs_stencil_side side,
		enum gs_stencil_op_type fail,
		enum gs_stencil_op_type zfail,
		enum gs_stencil_op_type zpass);

EXPORT void gs_set_viewport(int x, int y, int width, int height);
EXPORT void gs_get_viewport(struct gs_rect *rect);
EXPORT void gs_set_scissor_rect(const struct gs_rect *rect);

EXPORT void gs_ortho(float left, float right, float top, float bottom,
		float znear, float zfar);
EXPORT void gs_frustum(float left, float right, float top, float bottom,
		float znear, float zfar);

EXPORT void gs_projection_push(void);
EXPORT void gs_projection_pop(void);

EXPORT void     gs_swapchain_destroy(gs_swapchain_t *swapchain);

EXPORT void     gs_texture_destroy(gs_texture_t *tex);
EXPORT uint32_t gs_texture_get_width(const gs_texture_t *tex);
EXPORT uint32_t gs_texture_get_height(const gs_texture_t *tex);
EXPORT enum gs_color_format gs_texture_get_color_format(
		const gs_texture_t *tex);
EXPORT bool     gs_texture_map(gs_texture_t *tex, uint8_t **ptr,
		uint32_t *linesize);
EXPORT void     gs_texture_unmap(gs_texture_t *tex);
/** special-case function (GL only) - specifies whether the texture is a
 * GL_TEXTURE_RECTANGLE type, which doesn't use normalized texture
 * coordinates, doesn't support mipmapping, and requires address clamping */
EXPORT bool     gs_texture_is_rect(const gs_texture_t *tex);
/**
 * Gets a pointer to the context-specific object associated with the texture.
 * For example, for GL, this is a GLuint*.  For D3D11, ID3D11Texture2D*.
 */
EXPORT void    *gs_texture_get_obj(gs_texture_t *tex);

EXPORT void     gs_cubetexture_destroy(gs_texture_t *cubetex);
EXPORT uint32_t gs_cubetexture_get_size(const gs_texture_t *cubetex);
EXPORT enum gs_color_format gs_cubetexture_get_color_format(
		const gs_texture_t *cubetex);

EXPORT void     gs_voltexture_destroy(gs_texture_t *voltex);
EXPORT uint32_t gs_voltexture_get_width(const gs_texture_t *voltex);
EXPORT uint32_t gs_voltexture_get_height(const gs_texture_t *voltex);
EXPORT uint32_t gs_voltexture_get_depth(const gs_texture_t *voltex);
EXPORT enum gs_color_format gs_voltexture_get_color_format(
		const gs_texture_t *voltex);

EXPORT void     gs_stagesurface_destroy(gs_stagesurf_t *stagesurf);
EXPORT uint32_t gs_stagesurface_get_width(const gs_stagesurf_t *stagesurf);
EXPORT uint32_t gs_stagesurface_get_height(const gs_stagesurf_t *stagesurf);
EXPORT enum gs_color_format gs_stagesurface_get_color_format(
		const gs_stagesurf_t *stagesurf);
EXPORT bool     gs_stagesurface_map(gs_stagesurf_t *stagesurf, uint8_t **data,
		uint32_t *linesize);
EXPORT void     gs_stagesurface_unmap(gs_stagesurf_t *stagesurf);

EXPORT void     gs_zstencil_destroy(gs_zstencil_t *zstencil);

EXPORT void     gs_samplerstate_destroy(gs_samplerstate_t *samplerstate);

EXPORT void     gs_vertexbuffer_destroy(gs_vertbuffer_t *vertbuffer);
EXPORT void     gs_vertexbuffer_flush(gs_vertbuffer_t *vertbuffer);
EXPORT struct gs_vb_data *gs_vertexbuffer_get_data(
		const gs_vertbuffer_t *vertbuffer);

EXPORT void     gs_indexbuffer_destroy(gs_indexbuffer_t *indexbuffer);
EXPORT void     gs_indexbuffer_flush(gs_indexbuffer_t *indexbuffer);
EXPORT void     *gs_indexbuffer_get_data(const gs_indexbuffer_t *indexbuffer);
EXPORT size_t   gs_indexbuffer_get_num_indices(
		const gs_indexbuffer_t *indexbuffer);
EXPORT enum gs_index_type gs_indexbuffer_get_type(
		const gs_indexbuffer_t *indexbuffer);

#ifdef __APPLE__

/** platform specific function for creating (GL_TEXTURE_RECTANGLE) textures
 * from shared surface resources */
EXPORT gs_texture_t *gs_texture_create_from_iosurface(void *iosurf);
EXPORT bool     gs_texture_rebind_iosurface(gs_texture_t *texture,
		void *iosurf);

#elif _WIN32

EXPORT bool gs_gdi_texture_available(void);
EXPORT bool gs_shared_texture_available(void);

struct gs_duplicator;
typedef struct gs_duplicator gs_duplicator_t;

/**
 * Gets information about the monitor at the specific index, returns false
 * when there is no monitor at the specified index
 */
EXPORT bool gs_get_duplicator_monitor_info(int monitor_idx,
		struct gs_monitor_info *monitor_info);

/** creates a windows 8+ output duplicator (monitor capture) */
EXPORT gs_duplicator_t *gs_duplicator_create(int monitor_idx);
EXPORT void gs_duplicator_destroy(gs_duplicator_t *duplicator);

EXPORT bool gs_duplicator_update_frame(gs_duplicator_t *duplicator);
EXPORT gs_texture_t *gs_duplicator_get_texture(gs_duplicator_t *duplicator);

/** creates a windows GDI-lockable texture */
EXPORT gs_texture_t *gs_texture_create_gdi(uint32_t width, uint32_t height);

EXPORT void *gs_texture_get_dc(gs_texture_t *gdi_tex);
EXPORT void gs_texture_release_dc(gs_texture_t *gdi_tex);

/** creates a windows shared texture from a texture handle */
EXPORT gs_texture_t *gs_texture_open_shared(uint32_t handle);
#endif

/* inline functions used by modules */

static inline uint32_t gs_get_format_bpp(enum gs_color_format format)
{
	switch (format) {
	case GS_A8:          return 8;
	case GS_R8:          return 8;
	case GS_RGBA:        return 32;
	case GS_BGRX:        return 32;
	case GS_BGRA:        return 32;
	case GS_R10G10B10A2: return 32;
	case GS_RGBA16:      return 64;
	case GS_R16:         return 16;
	case GS_RGBA16F:     return 64;
	case GS_RGBA32F:     return 128;
	case GS_RG16F:       return 32;
	case GS_RG32F:       return 64;
	case GS_R16F:        return 16;
	case GS_R32F:        return 32;
	case GS_DXT1:        return 4;
	case GS_DXT3:        return 8;
	case GS_DXT5:        return 8;
	case GS_UNKNOWN:     return 0;
	}

	return 0;
}

static inline bool gs_is_compressed_format(enum gs_color_format format)
{
	return (format == GS_DXT1 || format == GS_DXT3 || format == GS_DXT5);
}

static inline uint32_t gs_get_total_levels(uint32_t width, uint32_t height)
{
	uint32_t size = width > height ? width : height;
	uint32_t num_levels = 0;

	while (size > 1) {
		size /= 2;
		num_levels++;
	}

	return num_levels;
}

#ifdef __cplusplus
}
#endif