From 99942f51efaa8639797e52d7b54d8b639f5d7733 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Wed, 24 Mar 2021 06:45:20 -0400
Subject: map: Render layer(s)

---
diff --git a/src/map.c b/src/map.c
index 314ae92..41d6af8 100644
--- a/src/map.c
+++ b/src/map.c
@@ -17,6 +17,7 @@
  * along with Dodge Balls.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <SDL.h>
 #include <expat.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -504,6 +505,93 @@ _db_tmx_map_start(void *pv, const char *name, const char **attr)
 	}
 }
 
+static void
+_db_map_render_layer(struct db_map *map, struct db_map_layer *layer,
+		SDL_Renderer *renderer, SDL_Texture *texture)
+{
+	int                i;
+	int                gid;
+	SDL_bool           tile_found;
+	struct db_tileset *tileset;
+	int                firstgid;
+	int                lastgid;
+	int                columns;
+	int                tilewidth;
+	int                tileheight;
+	SDL_Rect           tile_rect;
+	SDL_Rect           layer_rect;
+
+	for (i = 0; i < map->w * map->h; ++i) {
+		gid = layer->tiles[i];
+		if (gid == 0) {
+			continue;
+		}
+		tile_found = SDL_FALSE;
+		for (tileset = map->tileset_head; tileset != NULL;
+				tileset = db_tileset_next(tileset)) {
+			firstgid = db_tileset_firstgid(tileset);
+			lastgid = firstgid + db_tileset_tilecount(tileset);
+			if (gid >= firstgid && gid < lastgid) {
+				columns    = db_tileset_columns   (tileset);
+				tilewidth  = db_tileset_tilewidth (tileset);
+				tileheight = db_tileset_tileheight(tileset);
+				gid -= firstgid;
+				 tile_rect.x  = gid % columns;
+				 tile_rect.y  = gid / columns;
+				 tile_rect.w  = tilewidth;
+				 tile_rect.h  = tileheight;
+				 tile_rect.x *= tile_rect.w;
+				 tile_rect.y *= tile_rect.h;
+				layer_rect.x  = i % columns;
+				layer_rect.y  = i / columns;
+				layer_rect.w  = tilewidth;
+				layer_rect.h  = tileheight;
+				layer_rect.x *= layer_rect.w;
+				layer_rect.y *= layer_rect.h;
+				db_dbg("Blitting %dx%d tile at (%d,%d) "
+						"onto layer at (%d,%d)...",
+						tile_rect.w, tile_rect.h,
+						tile_rect.x, tile_rect.y,
+						layer_rect.x, layer_rect.y);
+				SDL_RenderCopy(renderer, texture,
+						&tile_rect, &layer_rect);
+				tile_found = SDL_TRUE;
+				break;
+			}
+		}
+		if (!tile_found) {
+			db_warn("Tile with gid 0x%8.8x not found", gid);
+		}
+	}
+}
+
+SDL_Texture *
+db_map_render(struct db_map *map, SDL_Renderer *renderer)
+{
+	struct db_tileset   *tileset;
+	SDL_Texture         *texture;
+	SDL_Texture         *old_target;
+	struct db_map_layer *layer;
+
+	for (tileset = map->tileset_head; tileset != NULL;
+			tileset = db_tileset_next(tileset)) {
+		db_tileset_create_texture(tileset, renderer);
+	}
+
+	texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA8888,
+			SDL_TEXTUREACCESS_TARGET, map->w, map->h);
+	old_target = SDL_GetRenderTarget(renderer);
+	SDL_SetRenderTarget(renderer, texture);
+
+	for (layer = map->layer_head; layer != NULL; layer = layer->next) {
+		_db_map_render_layer(map, layer, renderer, texture);
+	}
+
+	SDL_SetRenderTarget(renderer, old_target);
+
+	return texture;
+}
+
 struct db_map *
 db_map_new(const char *game_id, const char *level_id)
 {
diff --git a/src/map.h b/src/map.h
index a8ef337..2e6bd94 100644
--- a/src/map.h
+++ b/src/map.h
@@ -20,8 +20,11 @@
 #ifndef DB_MAP_H_
 #define DB_MAP_H_
 
+#include <SDL.h>
+
 struct db_map;
 
 struct db_map *db_map_new(const char *game_id, const char *level_id);
+SDL_Texture *db_map_render(struct db_map *map, SDL_Renderer *renderer);
 
 #endif  /* DB_MAP_H_ */
--
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