From 693d232ab6d8180292c776347a33b6c9c5f0f997 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Fri, 26 Mar 2021 09:45:52 -0400
Subject: map: Set collision tile bit fields

---
diff --git a/src/map.c b/src/map.c
index c134e6f..0d57a09 100644
--- a/src/map.c
+++ b/src/map.c
@@ -73,6 +73,8 @@ struct db_map {
 	int                  target_gid;
 	struct db_ball      *ball_head;
 	struct db_ball      *ball_tail;
+	Uint8               *p_col;
+	Uint8               *b_col;
 };
 
 static char *
@@ -748,6 +750,45 @@ _db_tmx_map_start(void *pv, const char *name, const char **attr)
 	}
 }
 
+static void
+_db_map_set_collision_tiles(struct db_map *map)
+{
+	struct db_map_layer *layer;
+	int                  i;
+	int                  gid;
+
+	db_dbg("Allocating %d bit field elements", (map->w * map->h + 7) / 8);
+	map->p_col = calloc((map->w * map->h + 7) / 8, sizeof(*map->p_col));
+	if (map->p_col == NULL) {
+		db_err("Failed to allocate memory");
+		return;
+	}
+	map->b_col = calloc((map->w * map->h + 7) / 8, sizeof(*map->p_col));
+	if (map->b_col == NULL) {
+		db_err("Failed to allocate memory");
+		free(map->p_col);
+		return;
+	}
+
+	for (layer = map->layer_head; layer != NULL; layer = layer->next) {
+		for (i = 0; i < map->w * map->h; ++i) {
+			gid = layer->tiles[i];
+			if (gid == 0) {
+				continue;
+			}
+			if (db_tile_player_collides(map->tileset_head, gid)) {
+				db_dbg("Tile %d collides: setting bit %d of "
+						"field element %d",
+						i, i % 8, i / 8);
+				map->p_col[i / 8] |= 1 << (i % 8);
+			}
+			if (db_tile_ball_collides(map->tileset_head, gid)) {
+				map->b_col[i / 8] |= 1 << (i % 8);
+			}
+		}
+	}
+}
+
 struct db_map *
 db_map_new(const char *game_id, const char *level_id)
 {
@@ -837,6 +878,8 @@ db_map_new(const char *game_id, const char *level_id)
 	XML_ParserFree(p);
 	fclose(fp);
 
+	_db_map_set_collision_tiles(map);
+
 	return map;
 }
 
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