Resolved Weird Interactions Between Kinematic Bodies in Havok

While using Havok physics, my dynamic bodies refuse to collide with a rotating rectangle. Everything works fine in Unity Physics, but I really want to use Havok for optimization purposes.

I've tried cranking up the solver iterations and changing the simulation steps to 1/120 and it somewhat helps but the dynamic objects still rarely collide with the rectangle. I've attached a video with the issue...

 

Kinematic bodies need to be 100% moved/rotated with velocity for their collisions to work properly

You can use "PhysicsVelocity.CalculateVelocityToTarget" to get a physicsVelocity that would bring a body to a target translation/rotation over the next frame

 

Ok so, I am trying to make the rotate script work with PhysicsVelocity.CalculateVelocityToTarget() but I'm unsure as to why its not working?

Here's the code I was using that worked in rotating the objects with a component StirRod:

Code (CSharp):

1.     protected override void OnUpdate()
2.     {
3.  
4.         var dt = Time.DeltaTime;
5.         var tickSpeed = 1f / Time.DeltaTime;
6.         // Rotate object
7.         Entities.ForEach((ref Rotation rot, ref StirRod stirComp) =>
8.         {
9.             quaternion yRot = quaternion.RotateY(80f * Mathf.Deg2Rad * dt);
10.  
11.             rot.Value = math.mul(rot.Value, yRot);
12.          
13.         }).Run();
14.     }

And here's the code I'm trying to use, now with the CalculateVelocityToTarget():

Code (CSharp):

1. [UpdateInGroup(typeof(FixedStepSimulationSystemGroup))]
2. [UpdateBefore(typeof(BuildPhysicsWorld))]
3. public class RotateObjectECS : SystemBase
4. {
5.    
6.     protected override void OnUpdate()
7.     {
8.  
9.         var dt = Time.DeltaTime;
10.         var tickSpeed = 1f / Time.DeltaTime;
11.  
12.         Entities
13.         .WithAll<StirRod>()
14.         .WithoutBurst()
15.         // Calculate contact events
16.         .ForEach((ref PhysicsVelocity vel, ref Rotation rotation, in Translation translation, in PhysicsMass mass) =>
17.         {
18.             quaternion yRot = quaternion.RotateY(80f * Mathf.Deg2Rad * dt);
19.             RigidTransform targetTransform = new RigidTransform(math.mul(rotation.Value, yRot), translation.Value);
20.  
21.             rotation.Value = math.mul(rotation.Value, yRot);
22.             vel = PhysicsVelocity.CalculateVelocityToTarget(mass, translation, rotation, targetTransform, tickSpeed);
23.         }).Run();
24.     }
25. }
26.  

edit for clarification: The kinematic body isn't moving anymore with the second script

 

Never mind, the script above totally works now. I had the body marked as "static" instead of "kinematic" when testing lol. Thank you so much for your help!