Rework rendering to allow multi-layer render

Internal Changelog:
- A scene now has a maximum amount of render texture. It is to be
  rendered in order of the array by the engine.
- A scene now needs an explicit render system to draw onto the render
  textures. The scene will also init the number of render layers
  needed.
- The change is to allow more separate of concerns when it comes to
  rendering. A scene can also now compartmentalise the rendered items,
  which hopefully make understanding the code easier.
- Update all exisiting code to use the new render system.

engine/engine.c

@@ -152,15 +152,32 @@ void init_scene(Scene_t* scene, render_func_t render_func, action_func_t action_
 
     //scene->scene_type = scene_type;
     scene->render_function = render_func;
+    scene->layers.n_layers = 0;
+    scene->bg_colour = WHITE;
+
     scene->action_function = action_func;
     scene->state = SCENE_ENDED;
     scene->time_scale = 1.0f;
 }
 
+bool add_scene_layer(Scene_t* scene, int width, int height, Rectangle render_area)
+{
+    if (scene->layers.n_layers >= MAX_RENDER_LAYERS) return false;
+
+    scene->layers.render_layers[scene->layers.n_layers].layer_tex = LoadRenderTexture(width, height);
+    scene->layers.render_layers[scene->layers.n_layers].render_area = render_area;
+    scene->layers.n_layers++;
+    return true;
+}
+
 void free_scene(Scene_t* scene)
 {
     sc_map_term_64(&scene->action_map);
     sc_array_term(&scene->systems);
+    for (uint8_t i = 0; i < scene->layers.n_layers; ++i)
+    {
+        UnloadRenderTexture(scene->layers.render_layers[i].layer_tex);
+    }
     free_entity_manager(&scene->ent_manager);
     deinit_particle_system(&scene->part_sys);
 }
@@ -178,10 +195,24 @@ inline void update_scene(Scene_t* scene, float delta_time)
 
 inline void render_scene(Scene_t* scene)
 {
-    if (scene->render_function != NULL)
+    BeginDrawing();
+    ClearBackground(scene->bg_colour);
+    for (uint8_t i = 0; i < scene->layers.n_layers; ++i)
     {
-        scene->render_function(scene);
+        RenderLayer_t* layer = scene->layers.render_layers + i;
+        Rectangle draw_rec = layer->render_area;
+        Vector2 draw_pos = {draw_rec.x, draw_rec.y};
+        draw_rec.x = 0;
+        draw_rec.y = 0;
+        draw_rec.height *= -1;
+        DrawTextureRec(
+            layer->layer_tex.texture,
+            draw_rec,
+            draw_pos,
+            WHITE
+        );
     }
+    EndDrawing();
 }
 
 inline void do_action(Scene_t* scene, ActionType_t action, bool pressed)

engine/engine.h

@@ -42,9 +42,22 @@ typedef void(*system_func_t)(Scene_t*);
 typedef void(*action_func_t)(Scene_t*, ActionType_t, bool);
 sc_array_def(system_func_t, systems);
 
+typedef struct RenderLayer {
+    RenderTexture2D layer_tex;
+    Rectangle render_area;
+}RenderLayer_t;
+
+typedef struct SceneRenderLayers {
+    RenderLayer_t render_layers[MAX_RENDER_LAYERS];
+    uint8_t n_layers;
+} SceneRenderLayers_t;
+
 struct Scene {
     struct sc_map_64 action_map; // key -> actions
     struct sc_array_systems systems;
+    SceneRenderLayers_t layers;
+    Color bg_colour;
+    // TODO: Render function is obsolete and should be treated like a system
     render_func_t render_function;
     action_func_t action_function;
     EntityManager_t ent_manager;
@@ -57,6 +70,7 @@ struct Scene {
     GameEngine_t *engine;
 };
 
+
 void init_engine(GameEngine_t* engine);
 void deinit_engine(GameEngine_t* engine);
 void process_inputs(GameEngine_t* engine, Scene_t* scene);
@@ -74,6 +88,7 @@ extern void do_action(Scene_t* scene, ActionType_t action, bool pressed);
 
 //void init_scene(Scene_t* scene, SceneType_t scene_type, system_func_t render_func, action_func_t action_func);
 void init_scene(Scene_t* scene, render_func_t render_func, action_func_t action_func);
+bool add_scene_layer(Scene_t* scene, int width, int height, Rectangle render_area);
 void free_scene(Scene_t* scene);
 
 #endif // __ENGINE_H

engine/engine_conf.h

@@ -1,6 +1,7 @@
 #ifndef _ENGINE_CONF_H
 #define _ENGINE_CONF_H
 
+#define MAX_RENDER_LAYERS 4
 #define MAX_ENTITIES 2048
 #define MAX_TEXTURES 16
 #define MAX_SPRITES 64
@@ -16,7 +17,6 @@
 #define MAX_PARTICLES 64
 
 #define MAX_TILE_TYPES 16
-
 #define N_TAGS 10
 #define N_COMPONENTS 20
 #define MAX_COMP_POOL_SIZE MAX_ENTITIES

scenes/editor_scene.c

@@ -40,6 +40,9 @@ static bool crate_activation = false;
 #define SELECTION_REGION_WIDTH (SELECTION_TILE_SIZE * MAX_SPAWN_TYPE)
 #define SELECTION_REGION_HEIGHT SELECTION_TILE_SIZE
 
+#define GAME_LAYER 0
+#define SELECTION_LAYER 1
+#define CONTROL_LAYER 2
 static char* get_spawn_selection_string(enum EntitySpawnSelection sel)
 {
     switch(sel)
@@ -80,41 +83,19 @@ static inline unsigned int get_tile_idx(int x, int y, const TileGrid_t* tilemap)
 }
 
 // This means you might be able to have two editor scene without running into problems
-static RenderTexture2D selection_section;
 #define SELECTION_RENDER_HEIGHT  (SELECTION_REGION_HEIGHT * 3)
 static void level_scene_render_func(Scene_t* scene)
 {
     LevelSceneData_t* data = &(CONTAINER_OF(scene, LevelScene_t, scene)->data);
 
     Entity_t* p_ent;
-    Rectangle draw_rec = data->game_rec;
-    draw_rec.x = 0;
-    draw_rec.y = 0;
-    draw_rec.height *= -1;
     static char buffer[512];
-    BeginDrawing();
-        ClearBackground(LIGHTGRAY);
-        DrawTextureRec(
-            data->game_viewport.texture,
-            draw_rec,
-            (Vector2){data->game_rec.x, data->game_rec.y},
-            WHITE
-        );
-        draw_rec.width = SELECTION_REGION_WIDTH;
-        draw_rec.height = -SELECTION_RENDER_HEIGHT;
-
 
     Vector2 draw_pos = {data->game_rec.x, data->game_rec.y + data->game_rec.height + SELECTION_GAP};
-        DrawTextureRec(
+    BeginTextureMode(scene->layers.render_layers[CONTROL_LAYER].layer_tex);
-            selection_section.texture,
+        ClearBackground(BLANK);
-            draw_rec,
-            draw_pos,
-            WHITE
-        );
-        
-        draw_pos.x = data->game_rec.x + current_spawn_selection * SELECTION_TILE_SIZE;
         DrawRectangleLines(
-            draw_pos.x, draw_pos.y,
+            data->game_rec.x + current_spawn_selection * SELECTION_TILE_SIZE, draw_pos.y,
             SELECTION_TILE_SIZE, SELECTION_TILE_SIZE, GREEN
         );
 
@@ -185,10 +166,10 @@ static void level_scene_render_func(Scene_t* scene)
         print_mempool_stats(buffer);
         DrawText(buffer, gui_x, gui_y, 12, BLACK);
 
-        gui_y += 300;
+        gui_y += 330;
         sprintf(buffer, "Chests: %u / %u", data->coins.current, data->coins.total);
         DrawText(buffer, gui_x, gui_y, 24, BLACK);
-    EndDrawing();
+    EndTextureMode();
 }
 
 static void render_editor_game_scene(Scene_t* scene)
@@ -212,7 +193,7 @@ static void render_editor_game_scene(Scene_t* scene)
     max.x = (int)fmin(tilemap.width, max.x + 1);
     max.y = (int)fmin(tilemap.height, max.y + 1);
 
-    BeginTextureMode(data->game_viewport);
+    BeginTextureMode(scene->layers.render_layers[GAME_LAYER].layer_tex);
         ClearBackground(WHITE);
         BeginMode2D(data->camera.cam);
         for (int tile_y = min.y; tile_y < max.y; tile_y++)
@@ -837,7 +818,7 @@ static void level_do_action(Scene_t* scene, ActionType_t action, bool pressed)
                 if (!pressed) metal_toggle = !metal_toggle;
                 const Color crate_colour = metal_toggle ? GRAY : BROWN;
                 Vector2 draw_pos = {SPAWN_CRATE * SELECTION_TILE_SIZE , 0};
-                BeginTextureMode(selection_section);
+                BeginTextureMode(scene->layers.render_layers[SELECTION_LAYER].layer_tex);
                 for (uint8_t i = SPAWN_CRATE; i <= SPAWN_CRATE_BOMB; ++i)
                 {
                     DrawRectangle(draw_pos.x, draw_pos.y, SELECTION_TILE_SIZE, SELECTION_TILE_SIZE, crate_colour);
@@ -1015,9 +996,22 @@ void init_sandbox_scene(LevelScene_t* scene)
         unsigned int tile_idx = (scene->data.tilemap.height - 1) * scene->data.tilemap.width + i;
         change_a_tile(&scene->data.tilemap, tile_idx, SOLID_TILE);
     }
-    selection_section = LoadRenderTexture(SELECTION_REGION_WIDTH, SELECTION_RENDER_HEIGHT);
 
-    BeginTextureMode(selection_section);
+    scene->scene.bg_colour = LIGHTGRAY;
+    add_scene_layer(
+        &scene->scene, scene->data.game_rec.width, scene->data.game_rec.height,
+        scene->data.game_rec
+    );
+    add_scene_layer(
+        &scene->scene, SELECTION_REGION_WIDTH, SELECTION_REGION_HEIGHT,
+        (Rectangle){
+            scene->data.game_rec.x, scene->data.game_rec.y + scene->data.game_rec.height + SELECTION_GAP,
+            SELECTION_REGION_WIDTH, SELECTION_REGION_HEIGHT
+        }
+    );
+    add_scene_layer(&scene->scene, 1280, 640, (Rectangle){0, 0, 1280, 640});
+
+    BeginTextureMode(scene->scene.layers.render_layers[SELECTION_LAYER].layer_tex);
         ClearBackground(LIGHTGRAY);
         Vector2 draw_pos = {0, 0};
         const Color crate_colour = metal_toggle ? GRAY : BROWN;
@@ -1228,6 +1222,7 @@ void init_sandbox_scene(LevelScene_t* scene)
     sc_array_add(&scene->scene.systems, &player_respawn_system);
     sc_array_add(&scene->scene.systems, &level_end_detection_system);
     sc_array_add(&scene->scene.systems, &render_editor_game_scene);
+    sc_array_add(&scene->scene.systems, &level_scene_render_func);
 
     // This avoid graphical glitch, not essential
     //sc_array_add(&scene->scene.systems, &update_tilemap_system);
@@ -1260,5 +1255,4 @@ void free_sandbox_scene(LevelScene_t* scene)
 {
     free_scene(&scene->scene);
     term_level_scene_data(&scene->data);
-    UnloadRenderTexture(selection_section); // Unload render texture
 }

scenes/game_scene.c

@@ -10,24 +10,15 @@
 
 static Tile_t all_tiles[MAX_N_TILES] = {0};
 
+#define GAME_LAYER 0
+#define CONTROL_LAYER 1
 static void level_scene_render_func(Scene_t* scene)
 {
     LevelSceneData_t* data = &(CONTAINER_OF(scene, LevelScene_t, scene)->data);
 
-    Rectangle draw_rec = data->game_rec;
-    draw_rec.x = 0;
-    draw_rec.y = 0;
-    draw_rec.height *= -1;
-
     static char buffer[512];
-    BeginDrawing();
+    BeginTextureMode(scene->layers.render_layers[CONTROL_LAYER].layer_tex);
-        ClearBackground(LIGHTGRAY);
+        ClearBackground(BLANK);
-        DrawTextureRec(
-            data->game_viewport.texture,
-            draw_rec,
-            (Vector2){data->game_rec.x, data->game_rec.y},
-            WHITE
-        );
 
         Entity_t* p_ent;
         sc_map_foreach_value(&scene->ent_manager.entities_map[PLAYER_ENT_TAG], p_ent)
@@ -45,13 +36,13 @@ static void level_scene_render_func(Scene_t* scene)
         //sprintf(buffer, "Spawn Entity: %s", get_spawn_selection_string(current_spawn_selection));
         //DrawText(buffer, gui_x, 240, 12, BLACK);
         sprintf(buffer, "Number of Entities: %u", sc_map_size_64v(&scene->ent_manager.entities));
-        DrawText(buffer, gui_x, 270, 12, BLACK);
+        DrawText(buffer, gui_x, 70, 12, BLACK);
         sprintf(buffer, "FPS: %u", GetFPS());
-        DrawText(buffer, gui_x, 320, 12, BLACK);
+        DrawText(buffer, gui_x, 120, 12, BLACK);
 
         print_mempool_stats(buffer);
-        DrawText(buffer, gui_x, 350, 12, BLACK);
+        DrawText(buffer, gui_x, 150, 12, BLACK);
-    EndDrawing();
+    EndTextureMode();
 }
 
 static void level_do_action(Scene_t* scene, ActionType_t action, bool pressed)
@@ -130,7 +121,7 @@ static void render_regular_game_scene(Scene_t* scene)
     max.x = (int)fmin(tilemap.width, max.x + 1);
     max.y = (int)fmin(tilemap.height, max.y + 1);
 
-    BeginTextureMode(data->game_viewport);
+    BeginTextureMode(scene->layers.render_layers[GAME_LAYER].layer_tex);
         ClearBackground(WHITE);
         BeginMode2D(data->camera.cam);
 
@@ -369,6 +360,14 @@ void init_game_scene(LevelScene_t* scene)
         (Rectangle){25, 25, 32*TILE_SIZE, 18*TILE_SIZE}
     );
 
+    // TODO: Remove the hardcoded window size
+    scene->scene.bg_colour = LIGHTGRAY;
+    add_scene_layer(
+        &scene->scene, scene->data.game_rec.width, scene->data.game_rec.height,
+        scene->data.game_rec
+    );
+    add_scene_layer(&scene->scene, 1280, 640, (Rectangle){0, 0, 1280, 640});
+
     create_player(&scene->scene.ent_manager);
     update_entity_manager(&scene->scene.ent_manager);
 
@@ -401,6 +400,7 @@ void init_game_scene(LevelScene_t* scene)
     sc_array_add(&scene->scene.systems, &player_respawn_system);
     sc_array_add(&scene->scene.systems, &update_water_runner_system);
     sc_array_add(&scene->scene.systems, &render_regular_game_scene);
+    sc_array_add(&scene->scene.systems, &level_scene_render_func);
     // This avoid graphical glitch, not essential
     //sc_array_add(&scene->scene.systems, &update_tilemap_system);
 

scenes/menu_scene.c

@@ -6,14 +6,14 @@
 static void menu_scene_render_func(Scene_t* scene)
 {
     MenuSceneData_t* data = &(CONTAINER_OF(scene, MenuScene_t, scene)->data);
-    BeginDrawing();
+    BeginTextureMode(scene->layers.render_layers[0].layer_tex);
         ClearBackground(RAYWHITE);
         DrawText("This is a game", 25, 220, 12, BLACK);
         UI_button(data->buttons, "Start");
         UI_button(data->buttons + 1, "Sandbox");
         UI_button(data->buttons + 2, "Continue");
         UI_button(data->buttons + 3, "Exit");
-    EndDrawing();
+    EndTextureMode();
 }
 
 static void exec_component_function(Scene_t* scene, int sel)
@@ -132,10 +132,10 @@ static void gui_loop(Scene_t* scene)
 
 void init_menu_scene(MenuScene_t* scene)
 {
-    //init_scene(&scene->scene, MENU_SCENE, &menu_scene_render_func, &menu_do_action);
     init_scene(&scene->scene, &menu_scene_render_func, &menu_do_action);
 
     sc_array_add(&scene->scene.systems, &gui_loop);
+    sc_array_add(&scene->scene.systems, &menu_scene_render_func);
     
     scene->data.buttons[0] = (UIComp_t) {
         .bbox = {25,255,125,30},
@@ -160,6 +160,7 @@ void init_menu_scene(MenuScene_t* scene)
     scene->data.max_comp = 4;
     scene->data.selected_comp = 0;
     scene->data.mode = MOUSE_MODE;
+    add_scene_layer(&scene->scene, 1280, 640, (Rectangle){0, 0, 1280, 640});
 
     sc_map_put_64(&scene->scene.action_map, KEY_UP, ACTION_UP);
     sc_map_put_64(&scene->scene.action_map, KEY_DOWN, ACTION_DOWN);

scenes/scene_impl.h

@@ -40,7 +40,7 @@ typedef struct LevelCamera {
 
 typedef struct LevelSceneData {
     TileGrid_t tilemap;
-    RenderTexture2D game_viewport;
+    // TODO: game_rec is actually obsolete since this is in the scene game layer
     Rectangle game_rec;
     LevelCamera_t camera;
     Sprite_t* tile_sprites[MAX_TILE_SPRITES];
@@ -60,7 +60,6 @@ void free_game_scene(LevelScene_t* scene);
 void init_sandbox_scene(LevelScene_t* scene);
 void free_sandbox_scene(LevelScene_t* scene);
 void init_level_scene_data(LevelSceneData_t* data, uint32_t max_tiles, Tile_t* tiles, Rectangle view_zone);
-//void init_level_scene_data(LevelSceneData_t* data, uint32_t max_tiles, Tile_t* tiles);
 void term_level_scene_data(LevelSceneData_t* data);
 void reload_level_tilemap(LevelScene_t* scene);
 void load_next_level_tilemap(LevelScene_t* scene);

scenes/scene_systems.c

@@ -4,13 +4,8 @@
 #include "constants.h"
 
 void init_level_scene_data(LevelSceneData_t* data, uint32_t max_tiles, Tile_t* tiles, Rectangle view_zone)
-//void init_level_scene_data(LevelSceneData_t* data, uint32_t max_tiles, Tile_t* tiles)
 {
-    //data->game_viewport = LoadRenderTexture(VIEWABLE_MAP_WIDTH*TILE_SIZE, VIEWABLE_MAP_HEIGHT*TILE_SIZE);
-    //data->game_rec = (Rectangle){25, 25, VIEWABLE_MAP_WIDTH*TILE_SIZE, VIEWABLE_MAP_HEIGHT*TILE_SIZE};
-    data->game_viewport = LoadRenderTexture(view_zone.width, view_zone.height);
     data->game_rec = view_zone;
-    //data->camera.cam = (Camera2D){0};
     memset(&data->camera, 0, sizeof(LevelCamera_t));
     data->camera.cam.rotation = 0.0f;
     data->camera.cam.zoom = 1.0f;
@@ -53,7 +48,6 @@ void term_level_scene_data(LevelSceneData_t* data)
     {
         sc_map_term_64v(&data->tilemap.tiles[i].entities_set);
     }
-    UnloadRenderTexture(data->game_viewport); // Unload render texture
 }
 
 bool load_level_tilemap(LevelScene_t* scene, unsigned int level_num)

water_test.c

@@ -23,6 +23,7 @@ static GameEngine_t engine =
 };
 
 static bool water_toggle = false;
+#define GAME_LAYER 0
 
 static void level_scene_render_func(Scene_t* scene)
 {
@@ -31,7 +32,7 @@ static void level_scene_render_func(Scene_t* scene)
 
     Entity_t* p_ent;
 
-    BeginTextureMode(data->game_viewport);
+    BeginTextureMode(scene->layers.render_layers[GAME_LAYER].layer_tex);
         ClearBackground(WHITE);
         BeginMode2D(data->camera.cam);
         for (size_t i = 0; i < tilemap.n_tiles; ++i)
@@ -177,19 +178,7 @@ static void level_scene_render_func(Scene_t* scene)
         EndMode2D();
     EndTextureMode();
 
-    Rectangle draw_rec = data->game_rec;
+    scene->bg_colour = water_toggle ? ColorAlpha(BLUE, 0.2) : LIGHTGRAY;
-    draw_rec.x = 0;
-    draw_rec.y = 0;
-    draw_rec.height *= -1;
-    BeginDrawing();
-        ClearBackground( water_toggle? ColorAlpha(BLUE, 0.2) : LIGHTGRAY);
-        DrawTextureRec(
-            data->game_viewport.texture,
-            draw_rec,
-            (Vector2){data->game_rec.x, data->game_rec.y},
-            WHITE
-        );
-    EndDrawing();
 }
 
 static inline unsigned int get_tile_idx(int x, int y, const TileGrid_t* tilemap)
@@ -413,11 +402,17 @@ int main(void)
     LevelScene_t scene;
     scene.scene.engine = &engine;
     init_scene(&scene.scene, &level_scene_render_func, &level_do_action);
+    init_entity_tag_map(&scene.scene.ent_manager, PLAYER_ENT_TAG, 4);
+    init_entity_tag_map(&scene.scene.ent_manager, DYNMEM_ENT_TAG, 16);
     init_level_scene_data(
         &scene.data, MAX_N_TILES, all_tiles,
         (Rectangle){25, 25, VIEWABLE_MAP_WIDTH*TILE_SIZE, VIEWABLE_MAP_HEIGHT*TILE_SIZE}
     );
     assert(scene.data.tilemap.n_tiles <= MAX_N_TILES);
+    add_scene_layer(
+        &scene.scene, scene.data.game_rec.width, scene.data.game_rec.height,
+        scene.data.game_rec
+    );
 
     for (size_t i = 0; i < scene.data.tilemap.width; ++i)
     {
@@ -441,6 +436,7 @@ int main(void)
     sc_array_add(&scene.scene.systems, &toggle_block_system);
     sc_array_add(&scene.scene.systems, &camera_update_system);
     sc_array_add(&scene.scene.systems, &player_dir_reset_system);
+    sc_array_add(&scene.scene.systems, &level_scene_render_func);
 
 
     sc_map_put_64(&scene.scene.action_map, KEY_R, ACTION_RESTART);