Bugfix multicollision solving

When multiple collisions occured in the same frame, Unity overrites their Collision Object of the OnCollisionEnter and OnCollisionStay methods with the latest collision. Since the Collision object is an reference type, the last collision got solved twice, while the second last collision got not solved. This bug is fixed now.

GuidewireSimulation/GuidewireSimulation/Assets/Guidewire_Assets/Scenes/CollisionTestScene_2Spheres_MeshPipe_Long_UnityVariant.unity

@@ -248,6 +248,10 @@ PrefabInstance:
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GuidewireSimulation/GuidewireSimulation/Assets/Guidewire_Assets/Scenes/CollisionTestScene_50Spheres_Aorta_Example_3.unity

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GuidewireSimulation/GuidewireSimulation/Assets/Guidewire_Assets/Scripts/CollisionDetectionPrimitive.cs

@@ -59,9 +59,12 @@ namespace GuidewireSim
          */
         private void OnCollisionEnter(Collision other)
         {
-            Debug.Log("trigger " + transform.name);
+            ContactPoint collisionContact = other.GetContact(0);
 
-            collisionHandler.RegisterCollision(this.transform, other, sphereID);
+            Vector3 contactPoint = collisionContact.point;
+            Vector3 collisionNormal = collisionContact.normal;
+
+            collisionHandler.RegisterCollision(this.transform, sphereID, contactPoint, collisionNormal);
         }
 
         /**
@@ -69,9 +72,12 @@ namespace GuidewireSim
          */
         private void OnCollisionStay(Collision other)
         {
-            Debug.Log("trigger " + transform.name);
+            ContactPoint collisionContact = other.GetContact(0);
+
+            Vector3 contactPoint = collisionContact.point;
+            Vector3 collisionNormal = collisionContact.normal;
 
-            collisionHandler.RegisterCollision(this.transform, other, sphereID);
+            collisionHandler.RegisterCollision(this.transform, sphereID, contactPoint, collisionNormal);
         }
     }
 }
\ No newline at end of file

GuidewireSimulation/GuidewireSimulation/Assets/Guidewire_Assets/Scripts/CollisionHandler.cs

@@ -32,10 +32,16 @@ namespace GuidewireSim
          * @param collision The Collision instance.
          * @param sphereID The unique ID of @p sphere.
          */
-        public void RegisterCollision(Transform sphere, Collision collision, int sphereID)
+        public void RegisterCollision(Transform sphere, int sphereID, Vector3 contactPoint, Vector3 collisionNormal)
         {
-            CollisionPair registeredCollision = new CollisionPair(sphere, collision, sphereID);
+            // Debug.Log(sphereID + " " + collision.GetContact(0).point);
+            CollisionPair registeredCollision = new CollisionPair(sphere, sphereID, contactPoint, collisionNormal);
             registeredCollisions.Add(registeredCollision);
+
+            // for (int index = 0; index < registeredCollisions.Count; index++)
+            // {
+            //     Debug.Log("entry" + index + " " + registeredCollisions[index].sphereID + " " + registeredCollisions[index].contactPoint);
+            // }
         }
 
         /**

GuidewireSimulation/GuidewireSimulation/Assets/Guidewire_Assets/Scripts/CollisionPair.cs

@@ -10,14 +10,16 @@ namespace GuidewireSim
     public struct CollisionPair
     {
         public Transform sphere; //!< The sphere object of the guidewire that was part of the collision.
-        public Collision vesselCollider; //!< The blood vessel object that was part of the collision.
+        public Vector3 contactPoint; //!< The contact point of the collision.
+        public Vector3 collisionNormal; //!< The normal of the collision.
         public int sphereID; //!< The ID of the sphere object of the guidewire that was part of the collision.
 
-        public CollisionPair(Transform sphere, Collision vesselCollider, int sphereID)
+        public CollisionPair(Transform sphere, int sphereID, Vector3 contactPoint, Vector3 collisionNormal)
         {
             this.sphere = sphere;
-            this.vesselCollider = vesselCollider;
             this.sphereID = sphereID;
+            this.contactPoint = contactPoint;
+            this.collisionNormal = collisionNormal;
         }
     }
 }
\ No newline at end of file

GuidewireSimulation/GuidewireSimulation/Assets/Guidewire_Assets/Scripts/CollisionSolvingStep.cs

@@ -43,13 +43,15 @@ namespace GuidewireSim
          */
         public void SolveCollisionConstraints(Vector3[] spherePositionPredictions, int solverStep, int constraintSolverSteps)
         {
+
             for (int collisionIndex = 0; collisionIndex < collisionHandler.registeredCollisions.Count; collisionIndex++)
             {
                 CollisionPair collisionPair = collisionHandler.registeredCollisions[collisionIndex];
                 int sphereID = collisionPair.sphereID;
                 Vector3 spherePositionPrediction = spherePositionPredictions[sphereID];
 
-                SolveCollisionConstraint(spherePositionPrediction, collisionPair, solverStep, out deltaPosition);
+                SolveCollisionConstraint(spherePositionPrediction, collisionPair.contactPoint, collisionPair.collisionNormal,
+                                         solverStep, out deltaPosition);
                 CorrectCollisionPredictions(sphereID, spherePositionPredictions, solverStep, constraintSolverSteps);
             }
         }
@@ -61,35 +63,27 @@ namespace GuidewireSim
          * @param solverStep The current iteration of the constraint solving step.
          * @attention Current calculation of the normal only works for spheres.
          */
-        protected virtual void SolveCollisionConstraint(Vector3 spherePositionPrediction, CollisionPair collisionPair, int solverStep,
-                                                        out Vector3 deltaPosition)
+        protected virtual void SolveCollisionConstraint(Vector3 spherePositionPrediction, Vector3 contactPoint, Vector3 collisionNormal,
+                                                        int solverStep, out Vector3 deltaPosition)
         {
-            ContactPoint contactPoint = collisionPair.vesselCollider.GetContact(0);
-            Vector3 otherPosition = contactPoint.otherCollider.transform.position;
-
-            Vector3 closestSurfacePoint = contactPoint.point;
-            Vector3 normalVector = contactPoint.normal;
-
             if (solverStep == 0)
             {
-                DrawCollisionInformation(spherePositionPrediction, contactPoint, otherPosition, closestSurfacePoint, normalVector);
+                DrawCollisionInformation(spherePositionPrediction, contactPoint, collisionNormal);
             }
 
-            deltaPosition = CalculateDeltaPosition(spherePositionPrediction, closestSurfacePoint, normalVector);
+            deltaPosition = CalculateDeltaPosition(spherePositionPrediction, contactPoint, collisionNormal);
         }
 
         /**
          * Draws the contact point, collision normal, and displacement corrections into the scene.
          */
-        protected void DrawCollisionInformation(Vector3 spherePositionPrediction, ContactPoint contactPoint, Vector3 otherPosition,
-                                              Vector3 closestSurfacePoint, Vector3 normalVector)
+        protected void DrawCollisionInformation(Vector3 spherePositionPrediction, Vector3 contactPoint, Vector3 collisionNormal)
         {
-            Debug.DrawLine(closestSurfacePoint, closestSurfacePoint + 10f * normalVector, Color.blue, 2f);
+            Debug.DrawLine(contactPoint, contactPoint + 10f * collisionNormal, Color.blue, 2f);
 
             DebugExtension.DrawPoint(spherePositionPrediction, Color.white);
 
-            DebugExtension.DrawPoint(contactPoint.point, Color.black);
-            DebugExtension.DrawPoint(closestSurfacePoint, Color.yellow);
+            DebugExtension.DrawPoint(contactPoint, Color.yellow);
         }
 
         /**
@@ -120,13 +114,10 @@ namespace GuidewireSim
                 initialPositionPrediction = spherePositionPredictions[sphereIndex];
             }
 
-            // spherePositionPredictions[sphereIndex] += Mathf.Pow(1 - (1 - collisionStiffness), 1 / 1000f) * deltaPosition;
             spherePositionPredictions[sphereIndex] += collisionStiffness * deltaPosition;
-            // spherePositionPredictions[sphereIndex] += deltaPosition;
 
             if (solverStep == constraintSolverSteps - 1)
             {
-                Debug.DrawLine(initialPositionPrediction, spherePositionPredictions[sphereIndex], Color.red, 2f);
                 DebugExtension.DrawPoint(spherePositionPredictions[sphereIndex], Color.red);
             }
         }

GuidewireSimulation/GuidewireSimulation/Assets/Guidewire_Assets/Scripts/CollisionSolvingStep_UnityVariant.cs

@@ -9,21 +9,5 @@ namespace GuidewireSim
      */
     public class CollisionSolvingStep_UnityVariant : CollisionSolvingStep
     {
-        protected override void SolveCollisionConstraint(Vector3 spherePositionPrediction, CollisionPair collisionPair, int solverStep,
-                                                         out Vector3 deltaPosition)
-        {
-            ContactPoint contactPoint = collisionPair.vesselCollider.GetContact(0);
-            Vector3 otherPosition = contactPoint.otherCollider.transform.position;
-
-            Vector3 closestSurfacePoint = contactPoint.point;
-            Vector3 normalVector = contactPoint.normal;
-
-            if (solverStep == 0)
-            {
-                DrawCollisionInformation(spherePositionPrediction, contactPoint, otherPosition, closestSurfacePoint, normalVector);
-            }
-
-            deltaPosition = CalculateDeltaPosition(spherePositionPrediction, closestSurfacePoint, normalVector);
-        }
     }
 }
\ No newline at end of file

GuidewireSimulation/GuidewireSimulation/UserSettings/EditorUserSettings.asset

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