From 16c3f22334cd4fbc022f3ea6a0bc1ea74e990b6c Mon Sep 17 00:00:00 2001
From: Erik Onarheim <erik.onarheim@gmail.com>
Date: Sat, 30 May 2026 17:36:39 -0500
Subject: [PATCH] fix: accidental shadowing in solver, could be foot gun

---
 .../collision/solver/realistic-solver.ts      |  8 +++---
 src/spec/vitest/realistic-solver-spec.ts      | 26 +++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/engine/collision/solver/realistic-solver.ts b/src/engine/collision/solver/realistic-solver.ts
index 1df0ca5839..abb3496f85 100644
--- a/src/engine/collision/solver/realistic-solver.ts
+++ b/src/engine/collision/solver/realistic-solver.ts
@@ -280,8 +280,8 @@ export class RealisticSolver implements CollisionSolver {
    */
   solvePosition(contacts: CollisionContact[]) {
     for (let i = 0; i < this.config.positionIterations; i++) {
-      for (let i = 0; i < contacts.length; i++) {
-        const contact = contacts[i];
+      for (let j = 0; j < contacts.length; j++) {
+        const contact = contacts[j];
         const bodyA = contact.bodyA;
         const bodyB = contact.bodyB;
 
@@ -350,8 +350,8 @@ export class RealisticSolver implements CollisionSolver {
   solveVelocity(contacts: CollisionContact[]) {
     // velocityIterations:
     for (let i = 0; i < this.config.velocityIterations; i++) {
-      for (let i = 0; i < contacts.length; i++) {
-        const contact = contacts[i];
+      for (let j = 0; j < contacts.length; j++) {
+        const contact = contacts[j];
         const bodyA = contact.bodyA;
         const bodyB = contact.bodyB;
 
diff --git a/src/spec/vitest/realistic-solver-spec.ts b/src/spec/vitest/realistic-solver-spec.ts
index ff3fc18026..a2cff34df9 100644
--- a/src/spec/vitest/realistic-solver-spec.ts
+++ b/src/spec/vitest/realistic-solver-spec.ts
@@ -44,4 +44,30 @@ describe('A RealisticSolver', () => {
     // Considers infinitesimally overlapping to no longer be overlapping and thus cancels the contact
     expect(contact.isCanceled()).toBe(true);
   });
+
+  it('should run the configured number of position and velocity iterations without variable shadowing issues', () => {
+    const config = { ...getDefaultPhysicsConfig().realistic, positionIterations: 3, velocityIterations: 4 };
+    const realisticSolver = new ex.RealisticSolver(config);
+
+    const actor1 = new ex.Actor({ x: 0, y: 0, width: 40, height: 40, collisionType: ex.CollisionType.Active });
+    const actor2 = new ex.Actor({ x: 30, y: 0, width: 40, height: 40, collisionType: ex.CollisionType.Active });
+
+    const contact = new ex.CollisionContact(
+      actor1.collider.get(),
+      actor2.collider.get(),
+      ex.Vector.Right,
+      ex.Vector.Right,
+      ex.Vector.Up,
+      [ex.vec(20, 0)],
+      [ex.vec(20, 0)],
+      null
+    );
+    contact.mtv = ex.vec(10, 0);
+
+    // Should not throw and should complete successfully with multiple iterations
+    realisticSolver.preSolve([contact]);
+    realisticSolver.solvePosition([contact]);
+    realisticSolver.solveVelocity([contact]);
+    realisticSolver.postSolve([contact]);
+  });
 });