From 6a1cb424c00a2298fbb5b05814a4a7ba52145168 Mon Sep 17 00:00:00 2001
From: Vlad Munteanu <munteanuvladm@gmail.com>
Date: Fri, 28 Aug 2026 01:03:23 +0300
Subject: [PATCH] Make ColliderCouplingSet iteration deterministic (use
 DeterministicState, as HGrid already does)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 src/geometry/mod.rs                        | 2 +-
 src/integrations/rapier/fluids_pipeline.rs | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/geometry/mod.rs b/src/geometry/mod.rs
index 5ee5daa..b2d8aaf 100644
--- a/src/geometry/mod.rs
+++ b/src/geometry/mod.rs
@@ -5,7 +5,7 @@ pub use self::contacts::{
     compute_contacts, compute_self_contacts, insert_boundaries_to_grid, insert_fluids_to_grid,
     HGridEntry, ParticlesContacts,
 };
-pub use self::hgrid::HGrid;
+pub use self::hgrid::{DeterministicState, HGrid};
 
 mod contact_manager;
 mod contacts;
diff --git a/src/integrations/rapier/fluids_pipeline.rs b/src/integrations/rapier/fluids_pipeline.rs
index d5d5f9c..bfa89c5 100644
--- a/src/integrations/rapier/fluids_pipeline.rs
+++ b/src/integrations/rapier/fluids_pipeline.rs
@@ -1,5 +1,5 @@
 use crate::coupling::CouplingManager;
-use crate::geometry::{HGrid, HGridEntry};
+use crate::geometry::{DeterministicState, HGrid, HGridEntry};
 use crate::object::{BoundaryHandle, BoundarySet, Fluid};
 use crate::solver::{DFSPHSolver, DfsphParameters, PressureSolver};
 use crate::TimestepManager;
@@ -171,14 +171,14 @@ pub struct ColliderCouplingEntry {
 /// Structure managing all the coupling between colliders from rapier with boundaries and fluids from salva.
 pub struct ColliderCouplingSet {
     /// The hashmap containing mappings from ColliderHandle to ColliderCouplingEntry
-    pub entries: HashMap<ColliderHandle, ColliderCouplingEntry>,
+    pub entries: HashMap<ColliderHandle, ColliderCouplingEntry, DeterministicState>,
 }
 
 impl ColliderCouplingSet {
     /// Create a new collider coupling manager.
     pub fn new() -> Self {
         Self {
-            entries: HashMap::new(),
+            entries: HashMap::with_hasher(DeterministicState),
         }
     }