From 2b5fd6f394ee99fcd33384467cfe427bd737bd2d Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Tue, 30 Mar 2021 03:16:19 -0400
Subject: ball: Use collision lines instead of tiles

---
diff --git a/src/ball.c b/src/ball.c
index 5c0497d..7f8aa3d 100644
--- a/src/ball.c
+++ b/src/ball.c
@@ -111,34 +111,27 @@ _db_ball_bounce(struct db_ball *ball, double col_x, double col_y)
 void
 db_balls_collisions(struct db_ball *ball)
 {
-	SDL_Rect        wall;
-	int             map_tw;
-	int             map_th;
-	int             x_min;
-	int             x_max;
-	int             y_min;
-	int             y_max;
-	int             x;
-	int             y;
-	double          col_x;
-	double          col_y;
-	struct db_ball *other;
-
-	wall.w = map_tw = db_map_get_tilewidth (ball->map);
-	wall.h = map_th = db_map_get_tileheight(ball->map);
-	x_min = floor((ball->x - ball->r) / map_tw);
-	x_max = ceil ((ball->x + ball->r) / map_tw);
-	y_min = floor((ball->y - ball->r) / map_th);
-	y_max = ceil ((ball->y + ball->r) / map_th);
-	for (y = y_min; y < y_max; ++y) {
-		for (x = x_min; x < x_max; ++x) {
-			if (db_map_tile_ball_collides(ball->map, x, y)) {
-				wall.x = x * map_tw;
-				wall.y = y * map_th;
-				if (db_col_cir_rect(ball->x, ball->y, ball->r,
-							&wall, &col_x, &col_y)){
-					_db_ball_bounce(ball, col_x, col_y);
-				}
+	struct db_map_line *line;
+	int                 line_x1;
+	int                 line_y1;
+	int                 line_x2;
+	int                 line_y2;
+	double              col_x;
+	double              col_y;
+	struct db_ball     *other;
+
+	/* Spinning balls shouldn't bounce off walls */
+	if (ball->sr == 0) {
+		for (line = db_map_get_lines(ball->map); line != NULL;
+				line = db_map_line_get_next(line)) {
+			db_map_line_get_coords(line, &line_x1, &line_y1,
+					&line_x2, &line_y2);
+			col_x = col_y = 0;  /* Shut up GCC */
+			if (db_col_cir_line(ball->x, ball->y, ball->r,
+						line_x1, line_y1,
+						line_x2, line_y2,
+						&col_x, &col_y)){
+				_db_ball_bounce(ball, col_x, col_y);
 			}
 		}
 	}
--
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