View Full Version : pfx question: smooth particle birth rate?

02 February 2006, 09:46 PM

is there any way to get pfx to draw particles between frames. for instance, if I set it to generate 5 per frame, it does 5 each frame. What I want is a smooth 5 per frame average, but that they be drawn on fractional frames so to speak, so that they don't all appear at once. I've tried enabling fractional keyframes, but that doesn't help...

does that make sense?

creating particles only on the frame makes my HVs appear "segmented" if I do size effects based on particle age. meaning that the scaling isn't smooth, but rather stepped.

ugh. I don't know if this makes sense or not...

02 February 2006, 09:57 PM
I'll check up on that, but what I've done before, is reducing the birth rate by for instance
four, and also stretching all other keyframes in the scene by a factor off four and then just
render out every four frames of the animation (which now off course is four times as long).
And then just stretching the speed of the render pass to 25 % (one fourth) of the rendered
range. This will mean the same as having a sub-frame birth rate sampling of 4.

edit: be sure to render with 200 % motion blur (four times the default 50) or render out a seperate motion vector pass.

02 February 2006, 11:16 PM
cool, thanks for that info. I ended up trying to do that exact same thing, except I multiplied by 10 instead of 4 because it's easy for me to remember that multiplier/divider.

I wouldn't have thought of that motion blur multiplier, though, so thanks for that heads-up.

I'm relieved that someone understood what I meant. Sub-frame birth rate sampling is a perfect term for it. Feature request, perhaps?


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02 February 2006, 11:16 PM
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