Don't update xsections if unnecessary.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/physics.h b/src/physics.h
index 92ec6fd..1ce2a9c 100644
--- a/src/physics.h
+++ b/src/physics.h
@@ -35,6 +35,7 @@ typedef struct {
 	bool running;
 	itc_chan ctl;
 	SDL_mutex *rotate_lock;
+	int64_t frame_index; // to avoid re-drawing the same fields
 } phy_sim;
 
 void phy_sim_destroy(phy_sim *sim);