What does "Fixed Bound" do in Niagara (GPU Emitter Properties)?


would anybody be so kind to explain what setting “Fixed Bounds” in a GPU Emitter within a Niagara system actually does?

The official explanation is circular, doesn’t really explain what these bounds are:

This checkbox enables or disables fixed bounds. If this is enabled, you can set the minimum and maximum fixed bounds for the entire system. It is also possible to set fixed bounds for individual emitters in their Emitter Properties item.

Also I find the concept mentioned in various posts, but none giving an actual definition of it.



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The bounds are used for culling – when the bounds overlap the view frustum, the particle system is rendered on screen.
Some particle systems also use whether they’re rendered, to determine whether they are simulated.
Fixed bounds let you get more control over this than you’d get from the automatic determination, either for performance (dont’ simulate/render a dust system just because a single particle happens to have flown very far out,) or for including things that automation might exclude (especially if particles are expanded in the shader.)


Thanks @jwatte, very clear explanation!