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LODs for APEX and 'usual' destructible meshes?

hey folks - I’m hoping to make a level that consists mostly of destructible meshes, and I know there are several possible issues related to performance… but I’d like to focus on the following three LOD-related questions right now

  • is it possible to have LODs on the ‘usual’ destructible meshes?
  • is it possible to have LODs on APEX destructible meshes?
  • is it possible to use Simplygon to generate LODs for ‘usual’ or APEX destructibles?

Thanks! David

Hi David,

You make reference to “Usual” and APEX destruction like they are two different things, but they are one in the same. :slight_smile:

If you mean “usual” to be the fracture tool in UE4 and APEX to be something made with PhysXLabs standalone or plugin application that would make more sense, which is my take-away here.

The answer for all your questions though is simply that you cannot have LODs for your destruction meshes. There is no way to import or make any custom LODs for these meshes.

However, it should be possible to setup a BP that you can have your Static version of the mesh with the LODs and when you are within range of the mesh swap it out with a destuctible mesh.

I’ve not tested or played around with trying this but something you should be possible to help you keep your FPS higher.

Thank you!

Tim

Hi Tim - Thanks for getting back to me.

You are right, I was thinking that the Apex Lab-generated destructibles and UE4-generated destructibles are different beasts. So they are identical in UE4, even though Apex Lab offers more tweaking options to tweak the setup?

That is correct. PhysXLabs has the ability to setup multiple depth layers for destruction whereas UE4 only allows one to be created within it’s fracture tool.

PhysXLabs also has the ability to use different masks for destruction aside from just the Voronoi fracture.

If you’ve not seen their tutorials you can check out some of them here.

You can control the type of fracture you want to have, for example if you want a tiled surface to chip off in tiles vs chunks or if you wanted a piece of wood to splinter like wood on it’s destruction that is possible with their tool.

The multiple layers provided through PhysXLabs is invaluable if you want a more realistic type of destruction effect. :slight_smile:

Tim

Cheers Tim, that helps a lot to know that all destructibles are the same :smiley: I’ve seen the PhysX Lab tutorials before when I worked with UDK, but that link might be useful to others.

If you folks have a moment, I’ve got 2 questions with regard to the ‘explosive force’ with which the destructible explodes:

  • Is there a way to control the force with which a destructible explodes… some of my destructible meshes just crumble slowly, and others fly apart. Changing the ‘Fracture Impulse Scale’ doesn’t seem to have any effect, and ‘Angular Damping’ and ‘Linear Damping’ perform a different function.

  • is there a way to transfer some of the momentum of the actor that destroys the destructible on to the chunks as they come apart. So, for example if a bullet shatters a vase, the chunks will tend to spray outwards along the path/direction of the bullet and not explode in a simple circular radius.

I’ve not toyed around with these too much, but there should be some tweaks in here to be made to get the look you’re after.

Sometimes to get the specific look you’re after you’ll want to use a combination of effects to make it look just right. Something like that would probably benefit more from using PhysXLabs to have your pieces disappear when hit and spawning a particle system.

Another method would be to use a modeling software to have a animation that can produce more specific kinds of looks. There are lots of tutorials out there using 3Ds Max and MassFX to get some cool destruction. Render that animation and have a simple animation play when that kind of effect happens.

With the dynamic destruction in UE4 and PhysXLabs can only take you so far. You’ll always want to augment this with some other effects or tricks to get a specific result. Games are all about faking things. :slight_smile:

Tim

If you’ve played games like Borderlands 2 which makes heavy use of PhysX. Physics simulated objects either don’t exist (particles/small objects) or have no physics simulation from a distance. Can’t be too hard to simply apply apex to your base LOD, and not to your others.

Thanks Tim, but I know this is going to seem bizarre because it is so fundamental, but I’ve pushed and pulled things around for several hours. I still haven’t found the basic UE4 settings which vary the amount by which the pieces fly apart, for want of a better word ‘explosion force’. When I collide with them, My Physx lab-destructible cylinder flies apart, and my in-engine generated destructible cube just cracks, then crumbles. I’ve covered all the PhysX tutorials… if you get a moment or two, would you mind seeing? From my time with UDK, there was a setting for this… I think it might be ‘Fracture Impulse Scale’, but it seems to be broken in this UE4 release.

Thanks for your thoughts on baked animations… if the system can sustain things, performance-wise, I’m trying to keep it live: fingers crossed that I won’t melt the system. The good news is that I figured out how to mimic the momentum transfer from the actor destroying the destructible on to the chunks, in blueprints anyway, using the hit point and spawning a force there. To make it even more realistic, one could even get the velocity of the destroying actor, and factor it into the force size. So one could just crack the mesh and - radiating from the point of contact - make the pieces fly apart using varying degrees of force, based on the velocity of the destroying actor.

@Silverbot… As you know, particle effects and (I’m 80% sure) rigid bodies can have LODs… so that’s Borderlands 2, or any other game really. However, specifically with regard to combining LOD 0 and an Apex destructible (which will likely have a particle component/child, but is not just a particle effect, or just a rigid body), I’d be careful before assuming that is a trivial matter. Actually, regrettably, I don’t think it is possible, out of the box… but there is probably a way with trigger volumes/switching meshes.

That doesn’t appear to be the case on my end. I’ve setup a simple test where I can apply damage on a key press and can see the mesh being pushed apart by the Fracture Impulse Scale. Feel free to give it a go.

All I did was setup the impulse scale to something like 5000 and applied the damage and impulse at the mesh location to see the results.

Link to project](Dropbox - Error)

@Tim… you are totally right, it does work and does what is needed. Thank you so much for taking the time to check it out… really appreciated! :smiley:

I’m not sure why I didn’t get it working. Though it seems dumber than I normally would, maybe I tested it with small impulse numbers like ‘5’, ‘10’ and ‘100’ instead of ‘5000’ so the difference wasn’t noticeable.