I have several characters from the game into the unwell that have scaling parents bones (for squash and stretch) with children bones that use physics.
As it is now, the physics simulation “breaks” or starts to look glitchy when scaling a parent bone.
Is there a recommended way of doing this scenario in unreal engine? /good workaround? /plans to fix in the future?
[Image Removed]
As an example i have attached this coconut ball with physics straws coming out from it’s head. When it starts jumping and squash and stretch scaling is applied to the main bone, the straws’ physics start to glitch out.
Steps to Reproduce
Make a ball with a physics appandege as child joints.
Create an animation where the ball joint scales to squash and stretch, while the child joints are using a physics asset to simulate.
The issues should be seen in the physics simulation of the scaled child joints that behave in a unpredictable way.
Hi, unfortunately this could be tricky to get something that works for you since scaling physics bodies while they are being simulated isn’t well supported. But I have a few questions to try and narrow down the problem:
- To confirm, the bones that are scaling don’t require physical simulation, just their children?
- How are you attempting to simulate the bones? Is this via RBAN, etc, in an anim graph or full simulation on these bones?
- What kind of simulated behaviour do you need on these bones, do you just need secondary motion, or also self collision, or world collision?
One option might be to run the physics simulation before the scale is applied. This can be a good approach when scaling the entire character, and when you are mostly interested in secondary motion. But it’s problematic with squash/stretch animation, as I’m assuming the scale data is coming directly from the animation sequences, so you would have to apply that scale to the bones after the simulation, which wouldn’t be straightforward.