Strange camera rotation with physics based skeletal meshes

Development World Creation
, , , , ,
1

Hi there,

I’ve been playing around with the vehicle blueprint, and I wanted to change the default “sedan” model. So I fired up Maya and rigged myself up a little car, and then imported it into UDK. I set it up as a skeletal mesh, and added a simple physics box like so:

26080-physics.jpg
26080-physics.jpg1385×821 150 KB

I then went and created a blueprint with a skeletal mesh as the root. I went ahead to attach 2 cameras to it:

26077-prob1.jpg
26077-prob1.jpg1920×837 116 KB

But when I press simulate, the car falls (as expected), but the cameras switch positions and rotate. Here’s a screenshot of them rotated:

26102-prob2.jpg
26102-prob2.jpg1914×1038 147 KB

I have no clue what’s going on. I noticed that the x-axis arrow on the collision box is pointed up in my physics asset editor. If I rotate the box so that its Z-axis is up, it still does the same thing. None of this happens if I use the default “sedan” from the vehicle template. Also, nothing rotates if my car has no physics bodies attached to it. It’s only as soon as it has a physics body…

Strange stuff. Hope someone can help :slight_smile:

2

This is essentially the same issue as

and here:

3

Ok it looks like I solved it!

In the export options of Blender, I had to set the forward and up axes, but also had to tick off the Apply Transform option. Looks like it works now!

4

These values may or may not work for your own case. I just played around with them until I got it looking right.

5

How would this apply to other 3D apps, like 3ds Max?

6

After a lot of searching I found the answer to this problem, copy paste my answer on another post:

Found a way to keep physics and stop crazy camera rotation: Add two Spring arms, one attached to each other. One will act as a “buffer”" for the rotation (shake).

Mesh > Spring 0 > Spring 1 > Camera

Make sure Spring 0 has no “inherent Pitch/yaw/roll”, while the opposite is true for Spring 1. Also make sure both have a bit of “Arm length”, each can take half of your desired distance. Don’t add any rotation or “collision test” to Spring 0.