replace categorized, sorted render queues with a single ordered 2d queue

src/context.h

@@ -20,9 +20,7 @@ typedef struct context {
     struct texture_cache texture_cache;
     struct input_state input;
 
-    struct sprite_primitive *render_queue_sprites;
-    struct rect_primitive *render_queue_rectangles;
-    struct circle_primitive *render_queue_circles;
+    struct primitive_2d *render_queue_2d;
     struct mesh_batch_item *uncolored_mesh_batches;
 
     struct audio_channel_item *audio_channels;

src/main.c

@@ -287,9 +287,7 @@ static bool initialize(void) {
 
     /* rendering */
     /* these are dynamic arrays and will be allocated lazily by stb_ds */
-    ctx.render_queue_sprites = NULL;
-    ctx.render_queue_rectangles = NULL;
-    ctx.render_queue_circles = NULL;
+    ctx.render_queue_2d = NULL;
     ctx.circle_radius_hash = NULL;
 
     textures_cache_init(&ctx.texture_cache, ctx.window);
@@ -324,8 +322,7 @@ static void clean_up(void) {
 
     input_state_deinit(&ctx.input);
 
-    arrfree(ctx.render_queue_sprites);
-    arrfree(ctx.render_queue_rectangles);
+    arrfree(ctx.render_queue_2d);
     textures_cache_deinit(&ctx.texture_cache);
 
     PHYSFS_deinit();

src/private/rendering.h

@@ -16,7 +16,6 @@ struct sprite_primitive {
     double rotation;
     SDL_BlendMode blend_mode;
     t_texture_key texture_key;
-    int layer;
     bool flip_x;
     bool flip_y;
 };
@@ -32,6 +31,22 @@ struct circle_primitive {
     t_fvec2 position;
 };
 
+enum primitive_2d_type {
+    PRIMITIVE_2D_SPRITE,
+    PRIMITIVE_2D_RECT,
+    PRIMITIVE_2D_CIRCLE,
+};
+
+struct primitive_2d {
+    enum primitive_2d_type type;
+
+    union {
+        struct sprite_primitive sprite;
+        struct rect_primitive rect;
+        struct circle_primitive circle;
+    };
+};
+
 /* union for in-place recalculation of texture coordinates */
 union uncolored_space_triangle {
     /* pending for sending, uvs are not final as texture atlases could update */

src/rendering.c

@@ -16,9 +16,7 @@ void render_queue_clear(void) {
     /* since i don't intend to free the queues, */
     /* it's faster and simpler to just "start over" */
     /* and start overwriting the existing data */
-    arrsetlen(ctx.render_queue_sprites, 0);
-    arrsetlen(ctx.render_queue_rectangles, 0);
-    arrsetlen(ctx.render_queue_circles, 0);
+    arrsetlen(ctx.render_queue_2d, 0);
 
     for (size_t i = 0; i < hmlenu(ctx.uncolored_mesh_batches); ++i)
         arrsetlen(ctx.uncolored_mesh_batches[i].value.primitives, 0);
@@ -31,7 +29,6 @@ void render_queue_clear(void) {
  * because they will be called multiple times in the main loop
  * before anything is really rendered
  */
-
 /* sprite */
 void push_sprite(char *path, t_frect rect) {
     struct sprite_primitive sprite = {
@@ -40,12 +37,16 @@ void push_sprite(char *path, t_frect rect) {
         .rotation = 0.0,
         .blend_mode = SDL_BLENDMODE_BLEND,
         .texture_key = textures_get_key(&ctx.texture_cache, path),
-        .layer = 0,
         .flip_x = false,
         .flip_y = false,
     };
 
-    arrput(ctx.render_queue_sprites, sprite);
+    struct primitive_2d primitive = {
+        .type = PRIMITIVE_2D_SPRITE,
+        .sprite = sprite,
+    };
+
+    arrput(ctx.render_queue_2d, primitive);
 }
 
 
@@ -55,13 +56,17 @@ void push_sprite_ex(t_frect rect, t_push_sprite_args args) {
         .color = args.color,
         .rotation = args.rotation,
         .blend_mode = args.blend_mode,
-        .texture_key =  textures_get_key(&ctx.texture_cache, args.path),
-        .layer = args.layer,
+        .texture_key = textures_get_key(&ctx.texture_cache, args.path),
         .flip_x = args.flip_x,
         .flip_y = args.flip_y,
     };
 
-    arrput(ctx.render_queue_sprites, sprite);
+    struct primitive_2d primitive = {
+        .type = PRIMITIVE_2D_SPRITE,
+        .sprite = sprite,
+    };
+
+    arrput(ctx.render_queue_2d, primitive);
 }
 
 
@@ -72,7 +77,12 @@ void push_rectangle(t_frect rect, t_color color) {
         .color = color,
     };
 
-    arrput(ctx.render_queue_rectangles, rectangle);
+    struct primitive_2d primitive = {
+        .type = PRIMITIVE_2D_RECT,
+        .rect = rectangle,
+    };
+
+    arrput(ctx.render_queue_2d, primitive);
 }
 
 
@@ -84,7 +94,12 @@ void push_circle(t_fvec2 position, float radius, t_color color) {
         .position = position,
     };
 
-    arrput(ctx.render_queue_circles, circle);
+    struct primitive_2d primitive = {
+        .type = PRIMITIVE_2D_CIRCLE,
+        .circle = circle,
+    };
+
+    arrput(ctx.render_queue_2d, primitive);
 }
 
 
@@ -123,76 +138,6 @@ void unfurl_triangle(const char *path,
 }
 
 
-/* compare functions for the sort in render_sprites */
-static int cmp_atlases(const void *a, const void *b) {
-    int index_a = ((const struct sprite_primitive *)a)->texture_key.id;
-    int index_b = ((const struct sprite_primitive *)b)->texture_key.id;
-
-    return (index_a > index_b) - (index_a < index_b);
-}
-
-
-static int cmp_blend_modes(const void *a, const void *b) {
-    SDL_BlendMode mode_a = ((const struct sprite_primitive *)a)->blend_mode;
-    SDL_BlendMode mode_b = ((const struct sprite_primitive *)b)->blend_mode;
-
-    return (mode_a > mode_b) - (mode_a < mode_b);
-}
-
-
-static int cmp_colors(const void *a, const void *b) {
-    t_color color_a = ((const struct sprite_primitive *)a)->color;
-    t_color color_b = ((const struct sprite_primitive *)b)->color;
-
-    /* check reds */
-    if (color_a.r < color_b.r)
-        return -1;
-    else if (color_a.r > color_b.r)
-        return 1;
-
-    /* reds were equal, check greens */
-    else if (color_a.g < color_b.g)
-        return -1;
-    else if (color_a.g > color_b.g)
-        return 1;
-
-    /* greens were equal, check blues */
-    else if (color_a.b < color_b.b)
-        return -1;
-    else if (color_a.b > color_b.b)
-        return 1;
-
-    /* blues were equal, check alphas */
-    else if (color_a.a < color_b.a)
-        return -1;
-    else if (color_a.a > color_b.a)
-        return 1;
-
-    /* entirely equal */
-    else
-        return 0;
-}
-
-
-static int cmp_layers(const void *a, const void *b) {
-    int layer_a = ((const struct sprite_primitive *)a)->layer;
-    int layer_b = ((const struct sprite_primitive *)b)->layer;
-
-    return (layer_a > layer_b) - (layer_a < layer_b);
-}
-
-
-/* TODO: not that we're SDL free we need to implement batching ourselves */
-/* necessary to allow the renderer to draw in batches in the best case */
-static void sort_sprites(struct sprite_primitive *sprites) {
-    size_t sprites_len = arrlenu(sprites);
-    qsort(sprites, sprites_len, sizeof *sprites, cmp_atlases);
-    qsort(sprites, sprites_len, sizeof *sprites, cmp_blend_modes);
-    qsort(sprites, sprites_len, sizeof *sprites, cmp_colors);
-    qsort(sprites, sprites_len, sizeof *sprites, cmp_layers);
-}
-
-
 static void upload_quad_vertices(t_frect rect) {
     /* client memory needs to be reachable on glDraw*, so */
     static float vertices[6 * 2];
@@ -366,25 +311,21 @@ static void render_circle(struct circle_primitive *circle) {
 }
 
 
-static void render_sprites(void) {
-    sort_sprites(ctx.render_queue_sprites);
+static void render_2d(void) {
+    for (size_t i = 0; i < arrlenu(ctx.render_queue_2d); ++i) {
+        struct primitive_2d *current = &ctx.render_queue_2d[i];
 
-    for (size_t i = 0; i < arrlenu(ctx.render_queue_sprites); ++i) {
-        render_sprite(&ctx.render_queue_sprites[i]);
-    }
-}
-
-
-static void render_rectangles(void) {
-    for (size_t i = 0; i < arrlenu(ctx.render_queue_rectangles); ++i) {
-        render_rectangle(&ctx.render_queue_rectangles[i]);
-    }
-}
-
-
-static void render_circles(void) {
-    for (size_t i = 0; i < arrlenu(ctx.render_queue_circles); ++i) {
-        render_circle(&ctx.render_queue_circles[i]);
+        switch (current->type) {
+            case PRIMITIVE_2D_SPRITE:
+                render_sprite(&current->sprite);
+                break;
+            case PRIMITIVE_2D_RECT:
+                render_rectangle(&current->rect);
+                break;
+            case PRIMITIVE_2D_CIRCLE:
+                render_circle(&current->circle);
+                break;
+        }
     }
 }
 
@@ -526,9 +467,7 @@ void render(void) {
 
         glEnable(GL_TEXTURE_2D);
 
-        render_sprites();
-        render_rectangles();
-        render_circles();
+        render_2d();
     }
 
     {

src/rendering.h

@@ -9,7 +9,6 @@
 
 typedef struct push_sprite_args {
     char *path;
-    int layer;
     t_color color;
     double rotation;
     SDL_BlendMode blend_mode;