Negative strength of radial force component not work on destructible meshes anymore

I have radial force component in my project with negative strength, which I use to simulate gravity(force strength set to -50000.0). And everything worked fine, until I tried UE 4.12.

I found that chunks of destructible meshes not attracted to the center of radial force component with negative strength anymore.

What can I do to solve this problem? I really need fix for that.

Hi Kelheor,

  • Does this occur in a clean, blank project with no additional content or is it limited to one project?
  • What steps can I take to reproduce this error on my end?
  • Can you show me your blueprint and destructible setups?

It seems that I found the problem. I created new project and repeated the situation. Everything worked well, so I dived deeper and found that force strength influence now heavily depends on size of object(which is not good sometimes). So at this moment I increased force strength from -50000 to -400000, but it seems that it’s a temporary solution. Maybe there is an option to remove size influence for destructible meshes?

Here the steps to recreate the situation.

Create blueprint-based first person template project with starter content

Open first person projectile blueprint

Set initial life span to 30 seconds

Remove all code in blueprint

Add radial force component

Set radius to 40000.0

Set force strength to -50000.0

Set impulse strength to 0.0

Add another one radial force component

Set radius to 50000.0

Set destructible damage to 100.0

Add OnComponentHit node for collision component

Add fire impulse node for second radial force and connect it to OnComponentHit node.

Open starter content folder, then shapes and find Shape_Sphere mesh

Right click on it and select create destructible mesh

Open it

Set damage threshold to 50

Set damage spread to 0.0

Check enable impact damage

Set impact damage to 1.0

Set debris lifetime min to 20, max to 30

Check accumulate damage

Check world support

Check debris timeout

Set support depth to 2

Set minimum fracture depth to 1

Check enable debris

Set debris depth to 1

Set cell site count to 50

Click on fractures the mesh’s root chunk on toolbar(blue cube icon)

Save all

Place destructible sphere on level.

Try to shoot projectile near sphere and see what happens.

Then try to play with sphere sizes. When you will increase the size of sphere, you will see that you need to increase force strength to achive the same effect.

Hi Kelheor,

After testing, I believe this is working as intended. Increasing the size of a destructible mesh increases the mass, which will in turn require more force to be able to achieve the results you are looking for. They are still affected by the radial force component, however it will simply take more force to move the actor to the new location.

And there will be no options to turn this off and make things like in previous versions of engine?

If you type in “Mass” in the detail’s pane of the asset in your level, you should be able to change the mass to something closer to what you are looking for.

I tried to set mass to zero, tried to check/uncheck simulate physics checkbox. Nothing changed. It seems this settings doesn’t affect destructible meshes.

Did you change the Mass Scale at all? Change it to .1 and see if this helps. When I did this, even extremely large chunks of my DM were affected by a similar amount of force as the boxes within a starting FP template.

No, it’s also not working. Here’s my result with videos:
Big sphere reacts differently than the small sphere.

Can you send me a sample project where this is occurring so I can take a look at what you have set up specifically?

Yes, sir:

I did some more digging and found that the mass for destructible mesh error is a known issue and is in our system as UE-5642. Unfortunately, I do not have a timeframe of when a fix will be implemented.

That means, there is no control over object’s scale influence? And I can only increase negative strength? :frowning:
Maybe you can add such control option in development todo list as a feature, so someone can implement it in future releases?

It is listed as a bug currently, so while it isn’t possible at present to affect destructible mesh chunk weight, it seems as though you should be able to, which is what this bug report is reflecting.