From 6b0df99a9d55385e11272f13bdfd51022d92be19 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Fri, 26 Mar 2021 09:34:18 -0400
Subject: tileset: Add collision functions

And fix collision bit field setting.
---
diff --git a/src/tileset.c b/src/tileset.c
index d8b3c03..c41f4ff 100644
--- a/src/tileset.c
+++ b/src/tileset.c
@@ -179,7 +179,7 @@ _db_tsx_property_start(void *pv, const char *name, const char **attr)
 			col = SDL_FALSE;  /* Shut up, GCC. */
 			db_xml_get_bool_attr(p, attr, "value", &col, 1);
 			if (col) {
-				tileset->b_col &= (1 << tileset->cur_tile);
+				tileset->b_col |= (1 << tileset->cur_tile);
 			}
 			db_dbg("                    Ball collision:   %s",
 					(col ? "true" : "false"));
@@ -195,7 +195,7 @@ _db_tsx_property_start(void *pv, const char *name, const char **attr)
 			col = SDL_FALSE;  /* Shut up, GCC. */
 			db_xml_get_bool_attr(p, attr, "value", &col, 1);
 			if (col) {
-				tileset->p_col &= (1 << tileset->cur_tile);
+				tileset->p_col |= (1 << tileset->cur_tile);
 			}
 			db_dbg("                    Player collision: %s",
 					(col ? "true" : "false"));
@@ -428,6 +428,32 @@ db_tileset_new(const char *game_id, const char *file, int firstgid,
 	return tileset;
 }
 
+SDL_bool
+db_tile_player_collides(struct db_tileset *tileset, int gid)
+{
+	for (; tileset != NULL; tileset = tileset->next) {
+		if (gid >= tileset->firstgid &&
+				gid < tileset->firstgid + tileset->tc) {
+			gid -= tileset->firstgid;
+			return tileset->p_col & 1 << gid;
+		}
+	}
+	return SDL_FALSE;
+}
+
+SDL_bool
+db_tile_ball_collides(struct db_tileset *tileset, int gid)
+{
+	for (; tileset != NULL; tileset = tileset->next) {
+		if (gid >= tileset->firstgid &&
+				gid < tileset->firstgid + tileset->tc) {
+			gid -= tileset->firstgid;
+			return tileset->b_col & 1 << gid;
+		}
+	}
+	return SDL_FALSE;
+}
+
 static SDL_Texture *
 _db_tileset_texture(struct db_tileset *tileset, SDL_Renderer *renderer)
 {
diff --git a/src/tileset.h b/src/tileset.h
index 652e1a3..e34117e 100644
--- a/src/tileset.h
+++ b/src/tileset.h
@@ -27,6 +27,10 @@ struct db_tileset;
 struct db_tileset *db_tileset_new(const char *game_id, const char *file,
 		int firstgid, int tilewidth, int tileheight,
 		struct db_tileset *prev);
+SDL_bool db_tile_player_collides(struct db_tileset *tileset, int gid)
+	__attribute__((__pure__));
+SDL_bool db_tile_ball_collides(struct db_tileset *tileset, int gid)
+	__attribute__((__pure__));
 int db_tile_render(struct db_tileset *tileset, SDL_Renderer *renderer, int gid,
 		SDL_Rect *dstrect);
 
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