1 files changed, 13 insertions, 9 deletions
diff --git a/src/sim/cell/materials/gas.rs b/src/sim/cell/materials/gas.rs
index 2ee7c00..af8f4fd 100644
--- a/src/sim/cell/materials/gas.rs
+++ b/src/sim/cell/materials/gas.rs
@@ -1,20 +1,24 @@
 use rand::RngExt;
 
-use crate::sim::cell_sim::sim::UpdateCtx;
+use crate::sim::cell_sim::sim::{PostUpdateAction, UpdateCtx};
 
 #[inline]
-pub fn sim_update(ctx: &mut UpdateCtx) {
+pub fn sim_update(ctx: &mut UpdateCtx) -> PostUpdateAction {
     // only allow upward movement some of the time to limit movement speed
-    if ctx.rng.random_range(0.0..1.0) > 0.8 && ctx.candidates_swap(&[(0, -1)]) {
-        return;
+    if ctx.rng.random_range(0.0..1.0) > 0.8
+        && ctx.swap_or_settle(&[(0, -1)]) == PostUpdateAction::None
+    {
+        return PostUpdateAction::None;
     }
     // same for each horizontal direction
     if ctx.rng.random_range(0.0..1.0) > 0.8
-        && ctx.candidates_swap(&[(1 - ctx.seqno_parity as i32 * 2, 0)])
+        && ctx.swap_or_settle(&[(1 - ctx.seqno_parity as i32 * 2, 0)]) == PostUpdateAction::None
     {
-        return;
+        return PostUpdateAction::None;
     }
-    if ctx.rng.random_range(0.0..1.0) > 0.8
-        && ctx.candidates_swap(&[(-1 + ctx.seqno_parity as i32 * 2, 0)])
-    {}
+    if ctx.rng.random_range(0.0..1.0) > 0.8 {
+        return ctx.swap_or_settle(&[(-1 + ctx.seqno_parity as i32 * 2, 0)]);
+    }
+
+    PostUpdateAction::Apply
 }