Prevent Rigidbody from Climbing Steep Slopes using Forces (C#)

Hello all!

I have been wracking my brain for weeks trying to solve this issue. Any assistance is greatly appreciated!

I’ve created a custom Rigidbody FPS controller. I need to prevent it from climbing steep slopes. Currently, when it steps onto a steep slope, it slides downwards, but since it can repeatedly step on and slide down such a slope in rapid succession, it causes a perceptible “jitter”. This is what I’m trying to prevent. I wish to use forces at the base of the slope to prevent the character from making that step onto it.

• With sufficient velocity, the Rigidbody should still be able to slide partway up, but after it has slid down again, it should remain at its base unless it runs again.

• I can’t utilize friction, because the Rigidbody uses a frictionless material to prevent other issues.

• Disabling forward input altogether doesn’t work, because the character should still slide along the base of the slope if the input isn’t exactly perpendicular to its base.

• Finally, force application must be precise, as the character itself be standing on a Rigidbody, which must remain unaffected.

The following code is very close, but the jitter returns when there is a high approach angle:

 private void SlopePreventClimb()
 {
     if ( !isGrounded || isSliding) return;
     
     var hit = new RaycastHit();
     var movementDir = Body.velocity.normalized;

     if ( !Physics.Raycast( transform.position + ( movementDir * 0.3f ), Vector3.down, out hit ) ) return;

     if (Vector3.Angle(Vector3.up, hit.normal) < 45f) return;

     var force = transform.InverseTransformVector( hit.normal / Time.fixedDeltaTime * Body.velocity.magnitude);
     force.y *= -1f;

     Body.AddForce(force, ForceMode.Acceleration);
 }

Again, I’m quite stumped. Any help would be greatly appreciated! Thank you in advance. :)