From 6fa5445fc076d7af82318c738dbd15a20f75ae56 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Sun, 28 Mar 2021 10:58:21 -0400
Subject: ball: Bounce off one wall per frame

---
diff --git a/src/ball.c b/src/ball.c
index d4c27a4..552aadd 100644
--- a/src/ball.c
+++ b/src/ball.c
@@ -118,8 +118,7 @@ db_balls_collisions(struct db_ball *ball)
 	int             x_max;
 	int             y_min;
 	int             y_max;
-	int             prev_col_x[2];
-	int             prev_col_y[2];
+	SDL_bool        bounce;
 	int             x;
 	int             y;
 	double          col_x;
@@ -132,10 +131,7 @@ db_balls_collisions(struct db_ball *ball)
 	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);
-	prev_col_x[0] = -1;
-	prev_col_x[1] = -1;
-	prev_col_y[0] = -1;
-	prev_col_y[1] = -1;
+	bounce = SDL_FALSE;
 	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)) {
@@ -143,30 +139,14 @@ db_balls_collisions(struct db_ball *ball)
 				wall.y = y * map_th;
 				if (db_col_cir_rect(ball->x, ball->y, ball->r,
 							&wall, &col_x, &col_y)){
-					if (x == prev_col_x[0]) {
-						continue;
-					} else if (x == prev_col_x[1]) {
-						continue;
-					} else if (y == prev_col_y[0]) {
-						continue;
-					} else if (y == prev_col_y[1]) {
-						continue;
-					}
-					_db_ball_bounce(ball, col_x, col_y);
-					if (prev_col_x[0] >= 0) {
-						prev_col_x[0] = x;
-					} else {
-						prev_col_x[1] = x;
-					}
-					if (prev_col_y[0] >= 0) {
-						prev_col_y[0] = y;
-					} else {
-						prev_col_y[1] = y;
-					}
+					bounce = SDL_TRUE;
 				}
 			}
 		}
 	}
+	if (bounce) {
+		_db_ball_bounce(ball, col_x, col_y);
+	}
 
 	/* Spinning balls shouldn't collide with any other balls */
 	if (ball->sr == 0) {
--
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