From 6f641e79d805a8308968d8155776edcc03d6624b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Davy=20H=C3=A9lard?= <davy.helard@gmail.com>
Date: Tue, 19 Nov 2024 21:04:27 +0100
Subject: [PATCH] Fix collision.

---
 .../Physics3DRuntimeBehavior.ts               | 28 +++++--------
 .../PhysicsCharacter3DRuntimeBehavior.ts      | 42 ++++++++++++-------
 2 files changed, 38 insertions(+), 32 deletions(-)

diff --git a/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts b/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
index fce8645e87bd..1af3439aed36 100644
--- a/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
+++ b/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
@@ -98,7 +98,6 @@ namespace gdjs {
     bodyInterface: Jolt.BodyInterface;
     /** Contact listener to keep track of current collisions */
     contactListener: Jolt.ContactListenerJS;
-    behaviorsByBodyID = new Map<number, gdjs.Physics3DRuntimeBehavior>();
     /** Avoid creating new vectors all the time */
     _tempVec3 = new Jolt.Vec3();
     _tempRVec3 = new Jolt.RVec3();
@@ -154,14 +153,6 @@ namespace gdjs {
 
         behaviorA.onContactBegin(behaviorB);
         behaviorB.onContactBegin(behaviorA);
-        this.behaviorsByBodyID.set(
-          bodyA.GetID().GetIndexAndSequenceNumber(),
-          behaviorA
-        );
-        this.behaviorsByBodyID.set(
-          bodyB.GetID().GetIndexAndSequenceNumber(),
-          behaviorB
-        );
       };
       this.contactListener.OnContactRemoved = (
         subShapePairPtr: number
@@ -171,15 +162,17 @@ namespace gdjs {
           Jolt.SubShapeIDPair
         );
 
-        const behaviorA = this.behaviorsByBodyID.get(
-          subShapePair.GetBody1ID().GetIndexAndSequenceNumber()
-        );
-        const behaviorB = this.behaviorsByBodyID.get(
-          subShapePair.GetBody2ID().GetIndexAndSequenceNumber()
-        );
+        // This is ok because bodies are not deleted during the Physics step.
+        const bodyLockInterface = this.physicsSystem.GetBodyLockInterface();
+        const bodyA = bodyLockInterface.TryGetBody(subShapePair.GetBody1ID());
+        const bodyB = bodyLockInterface.TryGetBody(subShapePair.GetBody2ID());
+
+        const behaviorA = bodyA.gdjsAssociatedBehavior;
+        const behaviorB = bodyB.gdjsAssociatedBehavior;
         if (!behaviorA || !behaviorB) {
           return;
         }
+
         behaviorA.onContactEnd(behaviorB);
         behaviorB.onContactEnd(behaviorA);
       };
@@ -188,7 +181,9 @@ namespace gdjs {
         bodyPtrB: number,
         manifoldPtr: number,
         settingsPtr: number
-      ): void => {};
+      ): void => {
+        // TODO we could rely on this event.
+      };
       this.contactListener.OnContactValidate = (
         bodyPtrA: number,
         bodyPtrB: number,
@@ -244,7 +239,6 @@ namespace gdjs {
         physicsBehavior.contactsStartedThisFrame.length = 0;
         physicsBehavior.contactsEndedThisFrame.length = 0;
       }
-      this.behaviorsByBodyID.clear();
       for (const physicsBehavior of this._registeredBehaviors) {
         physicsBehavior.updateBodyFromObject();
       }
diff --git a/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts b/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
index 99af31734f1e..964cd03e0f12 100644
--- a/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
+++ b/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
@@ -263,6 +263,8 @@ namespace gdjs {
       const body = sharedData.physicsSystem
         .GetBodyLockInterface()
         .TryGetBody(this.character.GetInnerBodyID());
+      // TODO This is not really reliable. We could choose to disable it and force user to use the "is on platform" condition.
+      body.SetCollideKinematicVsNonDynamic(true);
       return body;
     }
 
@@ -291,7 +293,7 @@ namespace gdjs {
       if (!this.character) {
         return;
       }
-      console.log('Step character');
+      // console.log('Step character');
 
       // console.log(
       //   'Character: ' +
@@ -372,6 +374,7 @@ namespace gdjs {
         );
       }
 
+      this.character.UpdateGroundVelocity();
       const groundVelocity = this.character.GetGroundVelocity();
 
       const forwardSpeed =
@@ -389,11 +392,21 @@ namespace gdjs {
       const sharedData = behavior._sharedData;
       const jolt = sharedData.jolt;
 
-      extendedUpdateSettings.mStickToFloorStepDown.Set(
-        0,
-        0,
-        Math.min(-Math.abs(forwardSpeed) * timeDelta * this._slopeClimbingFactor, groundVelocity.GetZ())
+      const onePixel = behavior._sharedData.worldInvScale;
+      const floorStepDownSpeedZ = Math.min(
+        -Math.abs(forwardSpeed) * this._slopeClimbingFactor,
+        groundVelocity.GetZ()
       );
+      if (
+        Math.abs(floorStepDownSpeedZ) <=
+        this._maxFallingSpeed * behavior._sharedData.worldInvScale
+      ) {
+        extendedUpdateSettings.mStickToFloorStepDown.Set(
+          0,
+          0,
+          -onePixel + floorStepDownSpeedZ * timeDelta
+        );
+      }
 
       this.character.SetRotation(behavior._body!.GetRotation());
       this.character.ExtendedUpdate(
@@ -420,14 +433,14 @@ namespace gdjs {
       //     this._currentFallSpeed
       // );
 
-      console.log(
-        'Ground: ' +
-          this.character.GetGroundVelocity().GetX() +
-          ' ' +
-          this.character.GetGroundVelocity().GetY() +
-          ' ' +
-          this.character.GetGroundVelocity().GetZ()
-      );
+      // console.log(
+      //   'Ground: ' +
+      //     this.character.GetGroundVelocity().GetX() +
+      //     ' ' +
+      //     this.character.GetGroundVelocity().GetY() +
+      //     ' ' +
+      //     this.character.GetGroundVelocity().GetZ()
+      // );
 
       // console.log(
       //   'Speed: ' +
@@ -477,8 +490,7 @@ namespace gdjs {
       this.hasPressedForwardKey = false;
       this.hasPressedJumpKey = false;
 
-      
-      console.log('END Step character');
+      // console.log('END Step character');
     }
 
     doStepPostEvents(instanceContainer: gdjs.RuntimeInstanceContainer) {}