townengine/src/textures.h

#ifndef TEXTURES_H
#define TEXTURES_H


#include <SDL2/SDL.h>
#include <stb_rect_pack.h>

#include <stdbool.h>


struct texture {
    SDL_Rect srcrect;           /* position in atlas */
    SDL_Surface *data;          /* original image data */
    SDL_Texture *loner_data;    /* loner textures store their data directly */
    int atlas_index;            /* which atlas the texture is in */
    int8_t layer;
};


struct texture_cache_item {
    char *key;
    struct texture value;
};


/* use the public API to create and manipulate instances of this structure */
struct texture_cache {
    /* from context */
    SDL_Window *window;
    SDL_Renderer *renderer;

    struct texture_cache_item *hash;
    struct texture_cache_item *loner_hash;

    stbrp_node *node_buffer; /* used internally by stb_rect_pack */

    SDL_Surface **atlas_surfaces;
    SDL_Texture **atlas_textures;
    int atlas_index;

    bool is_dirty;              /* current atlas needs to be recreated */
};


void textures_cache_init(struct texture_cache *cache, SDL_Window *window);
void textures_cache_deinit(struct texture_cache *cache);

/* for debugging */
void textures_dump_atlases(struct texture_cache *cache);

/* loads an image if it isn't in the cache, otherwise a no-op. */
/* can be called from anywhere at any time after init, useful if you want to */
/* preload textures you know will definitely be used */
void textures_load(struct texture_cache *cache, const char *path);

/* repacks the current texture atlas based on the texture cache */
void textures_update_current_atlas(struct texture_cache *cache);

/* returns a rect in a texture cache atlas based on a path, for drawing */
/* if the texture is not found, returns a zero-filled rect (so check w or h) */
SDL_Rect textures_get_srcrect(struct texture_cache *cache, const char *path);

/* returns which atlas the texture in the path is in, starting from 0 */
/* if the texture is not found, returns INT_MIN */
int textures_get_atlas_index(struct texture_cache *cache, const char *path);

/* returns a pointer to the atlas at `index` */
/* if the index is out of bounds, returns NULL. */
/* you can get the index via texture_get_atlas_index */
SDL_Texture *textures_get_atlas(struct texture_cache *cache, int index);

SDL_Texture *textures_get_loner(struct texture_cache *cache, const char *path);

/* returns the number of atlases in the cache */
size_t textures_get_num_atlases(struct texture_cache *cache);


#endif