partially done work on total source tree rework, separation of engine context and game context, generalization of renderer for different backends as well as web platform target

src/twn_textures_c.h

@@ -0,0 +1,92 @@
+#ifndef TWN_TEXTURES_H
+#define TWN_TEXTURES_H
+
+#include "twn_util.h"
+#include "twn_texture_modes.h"
+#include "twn_engine_api.h"
+#include "twn_gpu_texture.h"
+
+#include <SDL2/SDL.h>
+#include <stb_rect_pack.h>
+
+#include <stdbool.h>
+
+struct texture {
+    t_frect srcrect;            /* position in atlas */
+    SDL_Surface *data;          /* original image data */
+    int atlas_index;
+    gpu_texture loner_texture;       /* stored directly for loners, == 0 means atlas_index should be used */
+    gpu_texture repeating_texture;   /* separately allocated texture, for loners == loner_texture */
+    enum texture_mode mode;
+};
+
+
+struct texture_cache_item {
+    char *key;
+    struct texture value;
+};
+
+
+struct texture_cache {
+    SDL_Window *window;          /* from context */
+
+    struct texture_cache_item *hash;
+
+    stbrp_node *node_buffer;     /* used internally by stb_rect_pack */
+
+    SDL_Surface **atlas_surfaces;
+    gpu_texture *atlas_textures;      /* shared by atlas textures */
+    int atlas_index;             /* atlas that is currently being built */
+
+    bool is_dirty;               /* current atlas needs to be recreated */
+};
+
+/* type safe structure for persistent texture handles */
+typedef struct { uint16_t id; } t_texture_key;
+
+/* tests whether given key structure corresponds to any texture */
+#define m_texture_key_is_valid(p_key) ((p_key).id != (uint16_t)-1)
+
+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 if needed */
+/* any previously returned srcrect results are invalidated after that */
+/* call it every time before rendering */
+void textures_update_atlas(struct texture_cache *cache);
+
+/* returns a persistent handle to some texture in cache, loading it if needed */
+/* check the result with m_texture_key_is_valid() */
+t_texture_key textures_get_key(struct texture_cache *cache, const char *path);
+
+/* returns a rect in a texture cache of the given key */
+t_frect textures_get_srcrect(const struct texture_cache *cache, t_texture_key key);
+
+/* returns a rect of dimensions of the whole texture (whole atlas) */
+t_frect textures_get_dims(const struct texture_cache *cache, t_texture_key key);
+
+/* returns an identifier that is equal for all textures placed in the same atlas */
+int32_t textures_get_atlas_id(const struct texture_cache *cache, t_texture_key key);
+
+void textures_bind(const struct texture_cache *cache, t_texture_key key);
+
+void textures_bind_repeating(const struct texture_cache *cache, t_texture_key key);
+
+/* returns helpful information about contents of alpha channel in given texture */
+enum texture_mode textures_get_mode(const struct texture_cache *cache, t_texture_key key);
+
+/* returns the number of atlases in the cache */
+size_t textures_get_num_atlases(const struct texture_cache *cache);
+
+/* TODO: should recieve texture_cache, get_key optimization cache should be cleared some other way */
+void textures_reset_state(void);
+
+#endif