Is there a hardcoded GPU particle limit?

Development Asset Creation FX
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1

Does Unreal 4 impose a hardcoded limit on the number of GPU particles that can be spawned at any one time, or is it governed by the hardware in use?

We recently showcased a VR job at the Burn Energy Human Ignition F1 event, with as many particles as our GPU could handle, however would like to push it a little bit further. Our new demo machine is likely to be fitted with dual Titan Blacks, but if the engine won’t render particles after a certain point, we could probably save money by not getting the cards.

Thanks!

2

There is a hard limit of 2^10 (1,048,576). It’s easy to change if you have code. In ParticleGpuSimulation.cpp:

/** The texture size allocated for GPU simulation. */
const int32 GParticleSimulationTextureSizeX = 1024;
const int32 GParticleSimulationTextureSizeY = 1024;

You can increase the size of the textures allocated for simulation. Making both dimensions 2048 would give you ~4 million particles.

There is a separate limit of how many GPU particles are allowed to spawn per frame. That’s useful to prevent cases that would cause a hitch (e.g. generating 1M particles per frame would be prohibitive on the CPU). That can be modified at runtime or in the INI via the FX.MaxGPUParticlesSpawnedPerFrame console variable. It defaults to 2^10, the maximum number of particles currently allowed.

3

Sorry if this is a basic question, but which ini file do I edit and should the line read FX.MaxGPUParticlesSpawnedPerFrame = 2^11 ? or = 2048?

4

You can’t set the maximum via the INI yet. You will have to change code and recompile and Crow87 pointed out. That console variable limits how many GPU particles are allowed to spawn per frame. That can help with performance investigations to see if content is causing a hitch by spawning too many GPU particles in a single frame.

5

ah ok, that didn’t come across that obvious in his email.

i actually asked a similar question a while ago, and somehow missed part of homeRye’s answer which was how to fix the max spawn Particle stepping - FX - Epic Developer Community Forums playing with it now.

6

Hello, is there any way to change that limit, I would like to lower the limit for the game I’m craving for the console. What happens is you have 2,000 exploding barrels that admit or spawn and admitter and if they all blow up at one time you could imagine the freeze that happens until all the meters are spond and then destroyed so it’d be nice to build a limit the amount of a meters that could be in the game at any given time I guess that would help the this situation what do you think and if so how would you limit that?

7

Hello, is there any way to change that limit, I would like to lower the limit for the game I’m craving for the console. What happens is you have 2,000 exploding barrels that admit or spawn and admitter and if they all blow up at one time you could imagine the freeze that happens until all the meters are spond and then destroyed so it’d be nice to build a limit the amount of a meters that could be in the game at any given time I guess that would help the this situation what do you think and if so how would you limit that?