collision: Add rectangle/AABB collision functions

2 files changed, 29 insertions, 0 deletions

diff --git a/src/collision.c b/src/collision.c
index 2abd8a2..e17e78a 100644
--- a/src/collision.c
+++ b/src/collision.c
@@ -38,6 +38,31 @@ db_pt_in_rect(int x, int y, SDL_Rect *rect)
 	return 1;
 }
 
+void
+db_closest_pt_on_rect(int x, int y, SDL_Rect *rect, int *close_x, int *close_y)
+{
+	*close_x = x;
+	if (x < rect->x) {
+		*close_x = rect->x;
+	} else if (x > rect->x + rect->w) {
+		*close_x = rect->x + rect->w;
+	}
+	*close_y = y;
+	if (y < rect->y) {
+		*close_y = rect->y;
+	} else if (y > rect->y + rect->h) {
+		*close_y = rect->y + rect->h;
+	}
+}
+
+int
+db_col_cir_rect(int x, int y, int r, SDL_Rect *rect, int *col_x, int *col_y)
+{
+	db_closest_pt_on_rect(x, y, rect, col_x, col_y);
+	return (r * r) >=
+		((*col_x - x) * (*col_x - x) + (*col_y - y) * (*col_y - y));
+}
+
 int
 db_col_cir_cir(int x1, int y1, int r1, int x2, int y2, int r2)
 {
diff --git a/src/collision.h b/src/collision.h
index 58cd95e..896620b 100644
--- a/src/collision.h
+++ b/src/collision.h
@@ -23,6 +23,10 @@
 #include <SDL.h>
 
 int db_pt_in_rect(int x, int y, SDL_Rect *rect) __attribute__((__pure__));
+void db_closest_pt_on_rect(int x, int y, SDL_Rect *rect,
+		int *close_x, int *close_y);
+int db_col_cir_rect(int x, int y, int r, SDL_Rect *rect,
+		int *col_x, int *col_y);
 int db_col_cir_cir(int x1, int y1, int r1, int x2, int y2, int r2)
 	__attribute__((__const__));
 int db_col_pt_cir_cir(int x1, int y1, int r1, int x2, int y2, int r2,