Gravity fall instead of snapping to ground?

neurotrophy

Hi, I have been using V3 for a while and want to transition to V4. Currently when exploring the farm example, if climbing and you throw yourself away from the ladder or let go, or if you walk off of an edge, you immediately appear on the ground. Is there a way to turn off the snapping and have it so you fall or propel away using physics?

ChrisH

Hi neurotrophy

It doesn't look like gravity is supported but everything is in place to easily add that in.

The movement method you're looking for is called AxisMovement when you look how it works you'll find a chain that works out how much should PlayAreaAlias be moved based on input (other components like cameras, trackers etc are moving relatively to PlayAreaAlias).

The exact PositionMutator is found here /VRTK Prefabs//Locomotion//Movement//AxisMovement//SlidePlayArea/PositionUpdate if you navigate the stack to see where it gets values from you'll find Process method from AxesToVector3Processor

public virtual void Process()
{
    Vector3 axisDirection = Facade.SourceOfForwardDirection != null ? ApplyForwardSourceToAxis(CurrentAxisData) : CurrentAxisData;
    float multiplier = Facade.AxisUsageType == AxesToVector3Facade.AxisUsage.Incremental ? (Time.inFixedTimeStep ? Time.fixedDeltaTime : Time.deltaTime) : 1f;
    CurrentMovement = InputMask.Transform(axisDirection) * multiplier;
    Facade.Processed?.Invoke(CurrentMovement);
}

CurrentMovement is worked out using chain /VRTK Prefabs//Locomotion//Movement//AxisMovement//LeftController//HorizontalAndVerticalSlide//AxesToVector3/Internal - it seems to be working in 2 dimensions lat/lng.

If you were to add 3rd dimension I'd personally extend that chain to include gravity as one of coordinates, then you have to change AxisInputMask values to all on (1,1,1).

Combined that should apply general movement as well as falling / gravity.

You probably want to disable some of the dimensions while falling (ie. don't allow to move sideways) but generally that place should get you started.

As other potential approach you could perhaps add a rigidbody to PlayAreaAlias and use physics to get that working but that'd likely clash with existing PositionUpdate approach and cause you more grief than it's worth.

neurotrophy

Thanks for the reply.

I should have included more detail. Ideally, I want to use instant teleport when grounded instead of axis movement. The main mode of transport is climbing, zipline, throwing oneself, etc. with occasional teleportation. It seems that enabling BodyRepresentation (BodyCollisions/BodyRepresentation) enables a child rigidbody as well. So far, I have it set up so that the BodyRepresentation object is enabled and the Movement object is disabled when the Climb Stopped event is called. With that, if I throw myself off of a climbable object, I fall to the ground using physics. Then, once the Became Grounded event on the BodyRepresentation object is called, I enable Movement again and disable BodyRepresentation. This works okay-ish for climbing, though doesn't take care of the instances where the player steps off of a ledge; since the teleporter is still enabled, you just snap back to the ground.

Previously, I had tried keeping BodyRepresentation enabled at all times and disabling Movement when either the Climb Started event or Became Airborne event are called (and enabling Movement when the Became Grounded event is called), though it appears that Became Airborne and Became Grounded are being called constantly, even on flat ground, so I ended up with Movement flickering on and off, which causes flashes in the display and teleportation only works if you happen to click it when Movement is briefly enabled.

ChrisH

@ninjaconsultant I see, thanks for the details. It seems you're bit further in understanding this part of VRTK. I think you're approach to use Grounded/Airborne is sound - and in my head it shouldn't continuously fire - seems like a bug.

It seems to be located in here VRTK.Prefabs.Locomotion.BodyRepresentation.BodyRepresentationProcessor.CheckIfCharacterControllerIsGrounded

protected virtual bool CheckIfCharacterControllerIsGrounded()
{
    if (Character.isGrounded)
    {
        return true;
    }

    HeapAllocationFreeReadOnlyList<Collider> hitColliders = PhysicsCast.OverlapSphereAll(
        null,
        Character.transform.position + (Vector3.up * (Character.radius - Character.skinWidth - 0.001f)),
        Character.radius,
        1 << Character.gameObject.layer);
    foreach (Collider hitCollider in hitColliders)
    {
        if (hitCollider != Character
            && hitCollider != RigidbodyCollider
            && !ignoredColliders.Contains(hitCollider)
            && !Physics.GetIgnoreLayerCollision(
                hitCollider.gameObject.layer,
                Character.gameObject.layer)
            && !Physics.GetIgnoreLayerCollision(hitCollider.gameObject.layer, PhysicsBody.gameObject.layer))
        {
            return true;
        }
    }

    return false;
}

That Character.isGrounded returns false (even when on the ground while you move - maybe an issue with how that function works or maybe something is moving that controller a tiny bit along y axis making it ungrounded.

It seems that guys have seen that and put some workaround in place by using PhysicsCast.OverlapSphereAll the only problem is as you can see it'll ignore layer that CharacterController is on in this case Default, the floor on farm demo is also on that layer, if you change it to something else it'll be captured in that call and function will return true.

This makes it better as grounded/airborne will no longer continuously trigger, when you climb though - this Character.isGrounded returns true sometimes and toggles events.

Perhaps you can look into exact reason why this happens and getting that fixed, maybe as a workaround you can combine that with check for Climbinbing state to filter out those Grounded/Airborne false-positives.