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How to put all the original emitting points from a POP replicate node into one group?


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I'm currently working on a POP netowork to simulate raindrops on a window, and am trying to isolate the original particles from which the trails (in red) are emitted as per an emit attribute using the POP replicate node, so that I can selecting apply a POP interact force to them. However, I'm really struggling to find a way to isolate those points. I couldnt find any reference to the original points within the POP replicate node, apart from the fact that their ID is added to the sourceptnum attribute. Am I missing an obvious solution? Thanks

POP Replicate Question.JPG

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On 8/18/2021 at 2:38 PM, Atom said:

The Pop Source node and the Pop Replicate node both offer a Stream tab. This places the points generated by those nodes into those groups. Set them differently, then you can detect them after simulation by their candidacy in a group


Thanks for taking the time to make the example file :) I had a look at your file and the outcome seems to be the same as what I have in the above picture, with all the original points (from the pop source) highlighted in green, regardless of whether they've actually emitted any points themselves. I want to only highlight the points that Houdini decides, whether by probabilistic emission or by an emit attribute, to emit points from in the POP replicate. So there should be three colours, the emitted points from the POP replicate, original POP source points from which nothing has been emitted and original points from which points have been emitted (as per the circled points in my picture).

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Then extend it by adding the justborn group to your emitter. Then you'll have access to the points, before they emit. You could also "pre-scatter" those and use All Points as the input source to isolate those points that generate particles.


Edited by Atom
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