Constrain velocity on only x & z (let the jump fly free!)

Questions & Answers
1

I’m using the oft sited (yet probably ham-handed) method of constraining velocity:

	if (Mathf.Abs (rigidbody.velocity.magnitude) > maxSpeed){
		rigidbody.velocity = rigidbody.velocity.normalized * maxSpeed;
	}

Hopefully I’ll work out something a bit more robust in the future, but for now my main problem is that this formula slows down the vertical motion of my jumps. I only want the magnitude of motion across the ground (x and z axes) to be affected by the velocity constraint, not z motion.

I’ve tried setting an “OnGround” bool to use as a second qualifier for the velocity constraint, which is controlled by the OnCollision trio of functions, but there always seems to be at least a frame after the jump impulse is fired where it still thinks it’s in contact with the ground and thus ruins the jump. Any insight out there?

2

Assuming you are talking about world directions, you can do it this way:

var v = rigidbgody.velocity;
var f = v.y;
v.y = 0.0;
v = Vector3.ClampMagnitude(maxSpeed);
v.y = f;
rigidbody.velocity = v;

‘maxSpeed’ now represents only ground speed.

Note on your original code. Vector3.magnitude is always positive, so you don’t have to do a Mathf.Abs().

3

@robertbu got me thinking in a good direction (saving and replacing the y velocity) and I made my own version.

		float saveVelY = rigidbody.velocity.y;
		rigidbody.velocity = new Vector3 (rigidbody.velocity.x, 0.0f, rigidbody.velocity.z);
		rigidbody.velocity = Vector3.ClampMagnitude (rigidbody.velocity,MovementScript.maxSpeed);
		rigidbody.velocity = new Vector3(rigidbody.velocity.x,saveVelY,rigidbody.velocity.z);