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GPU Sprites disappear once out of view

I have a particle system using GPU sprites and when it plays in game, there’s a blood splurt and some flesh bits that go flying out - these flesh bits are the GPU sprites, they have collision and linger for awhile. However, if I move my camera away from the flesh bits, they disappear and when I come back to the spot where they should be lying on the floor, they’re not there.

I’ve checked ‘Use Fixed Relative Bounding Box’ and set min and max to all kinds of sizes and the problem persists. It seems like the bounding box disappears. When I first set it, I can see the bounding box is massive in the editor but as soon as I press play, the particles disappear and the bounding box is not there anymore.

Is there any other option that can cause the GPU sprites to not render?

From what I remember, no, that’s just how GPU particles work.

Epic had a great YouTube video about the pros, cons, and work arounds for different particles. There might be some useful information in here.

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Particle Effect Collision | Live Training | Unreal Engine - YouTube

Hey, thanks for that link. It turns out (as you point out) that what I was experiencing is the normal behaviour for GPU Sprites but there is a trick he uses where he turns on ‘Generate Mesh Distance Fields’ in the project settings and sets the GPU Sprite’s collision to Distance Fields (instead of Scene Depth).

That fixed my problem. For anyone who might run into this problem in the future, the problem is with scene depth collision on the GPU Sprites. As soon as you go out of view, the GPU can’t calculate the collision and the particles fall through the floor.

This, of course, assumes you want to use Distance Fields - the cons are discussed in that video posted above.

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