feat: Bepu physics integration

[Eideren]

PR Details

Adds support for Bepu Physics as an alternative physics engine, we'll keep the current one but will move our focus towards this new one instead.

Motivation

Unified ecosystem, improved performance, flexibility and debugging experience compared to Bullet's physics engine.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My change requires a change to the documentation.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have built and run the editor to try this change out.

Post release

• Query mesh material index from physics tests
• Ragdoll utilities
• Wider support of the different mesh formats (ExtractBepuMesh)
• Wait for Freeze and explosive memory growth when newing a ConvexHull with specific input bepu/bepuphysics2#325 to add convex support
• Ask if Norbo is available to check some areas that could be improved
• Navigation

A huge thanks goes to @Nicogo1705 and @Doprez for working on this. As well as @RossNordby for Bepu and dealing with our nonsense.

COMMIT HISTORY HAS BEEN PRESERVED, DO NOT SQUASH OR REBASE - JUST MERGE

[Eideren]

@Doprez I removed the demo project from the main solution, it couldn't be built from there anyway. This will take care of the missing packages issue.
As for the character issue it is fixed now.
I also created a test to cover the raycast issue you mentioned earlier but could not repro it in the current state. If you do find it again let me know.

[Doprez]

@Doprez I removed the demo project from the main solution, it couldn't be built from there anyway. This will take care of the missing packages issue. As for the character issue it is fixed now. I also created a test to cover the raycast issue you mentioned earlier but could not repro it in the current state. If you do find it again let me know.

Sounds good! The issue wasnt actually the raycast, it was the fact that the CharacterComponent kept a reference to a disposed object and then tried to look for that reference in the contact removed handler. Ill mess around with your changes and test it out. It was this line that caused it https://github.com/Eideren/xenko/blob/cc05d516d22e0d49b6c1bdc8d29f40520bb4f9eb/sources/engine/Stride.BepuPhysics/Stride.BepuPhysics/CharacterComponent.cs#L158 since the component that was supposed to be returned was removed when the scene is set to null.

I can also create the situation that caused the problem in a repro later it was pretty easy to recreate once I figured out where it was happening.

[Doprez]

I just tested the issues I was having with removing objects touching the character component and I cant seem to recreate it anymore!

edit: Also the test you added for OnContact removal should be exactly what was happening to me.

[Doprez]

One thing to mention about the character controller changes. It only jumps while moving, when standing still it does not seem to jump at all for some reason. I can look into it in a bit but maybe you already know why.

[Eideren]

@Doprez I can't repro in the characterscene demo, what's your setup ?

[Doprez]

Maybe its my PlayerMover class then? here is my jump code:

	public override void Update(float deltaTime)
	{
		if (_queueJump.TryReceive()) QueueJump();

		Jump();
        }

	private void QueueJump()
	{
		// Jump is queued to allow for a small time frame to press the jump button.
		// This is to allow for a more responsive jump.
		// I may want to base the timer on when the isGrouded state is true so that the player can jump ledges without needing to be grounded.
		_jumpQueued = true;
		_jumpTimeFrame.Start();
	}

	/// <summary>
	/// makes the player jump.
	/// <para>power is determined by the JumpPower variable and uses the CharacterComponent.IsGrounded variable to validate if player can jump.</para>
	/// </summary>
	public void Jump()
	{
		if (!_isCrouched && _jumpQueued && _jumpTimeFrame.ElapsedMilliseconds < _jumpTimeLeniencyMilliseconds)
		{
			_jumpTimeFrame.Reset();
			_jumpQueued = false;
			_character.JumpForce = JumpPower;
			_character.TryJump();
		}
	}

And it gets the input for jump like this:

			if (Input.IsKeyPressed(key))
			{
				JumpEvent.Broadcast();
			}

Ill try out the demo character later this one was mostly taken from the Bullet demo so maybe I mixed something that was wrong.

[Doprez]

Sorry, I meant to get back sooner for the CharacterController issue I was having. It does seem to be fine when using the demo code so I must have had something weird with my previous implementation.