Nuke particles escaping bounce node with geometry input

Question

I created a sphere emitting particles in Nuke. Around that sphere is another sphere connected to a particle bounce which is set to kill the particles. Some particles seem to slip through though. Why is this, and how can I fix it?

    #! /Applications/Nuke9.0v3/Nuke9.0v3.app/Contents/MacOS//libnuke-9.0.3.dylib -nx
version 9.0 v3
define_window_layout_xml {<?xml version="1.0" encoding="UTF-8"?>
<layout version="1.0">
    <window x="0" y="23" w="1440" h="873" screen="0">
        <splitter orientation="1">
            <split size="910"/>
            <splitter orientation="1">
                <split size="34"/>
                <dock id="" hideTitles="1" activePageId="Toolbar.1">
                    <page id="Toolbar.1"/>
                </dock>
                <split size="872"/>
                <splitter orientation="2">
                    <split size="497"/>
                    <dock id="" activePageId="Viewer.1" focus="true">
                        <page id="Viewer.1"/>
                    </dock>
                    <split size="350"/>
                    <dock id="" activePageId="DAG.1">
                        <page id="DAG.1"/>
                        <page id="Curve Editor.1"/>
                        <page id="DopeSheet.1"/>
                    </dock>
                </splitter>
            </splitter>
            <split size="526"/>
            <dock id="" activePageId="Properties.1">
                <page id="Properties.1"/>
            </dock>
        </splitter>
    </window>
</layout>
}
Root {
 inputs 0
 name /particle.nk
 frame 47
 format "2048 1556 0 0 2048 1556 1 2K_Super_35(full-ap)"
 proxy_type scale
 proxy_format "1024 778 0 0 1024 778 1 1K_Super_35(full-ap)"
}
Sphere {
 inputs 0
 display wireframe
 render_mode off
 radius 3
 name Sphere1
 xpos -417
 ypos 81
}
Sphere {
 inputs 0
 name Sphere2
 xpos -410
 ypos -50
}
Sphere {
 inputs 0
 display wireframe
 render_mode off
 name Sphere3
 xpos -266
 ypos -144
}
push 0
ParticleEmitter {
 inputs 3
 name ParticleEmitter1
 xpos -261
 ypos -50
}
ParticleBounce {
 inputs 2
 out_bounce_mode kill
 in_bounce_mode kill
 object input
 name ParticleBounce1
 selected true
 xpos -261
 ypos 77
}
Viewer {
 frame 47
 frame_range 1-100
 name Viewer1
 xpos -261
 ypos 176
}

Answer 1

This looks like a bug in Nuke's ParticleBounce node. The geometry input is new to Nuke 9, which was released pretty recently.

That said, the bug seems to manifest only in this idealized environment of two spheres. The first sphere (radius 1) emits the particles, and the second sphere (radius 3) kills them. It is likely because of the exact alignment between vertices that causes it to penetrate.

Rotating one of the two spheres 0.1 degrees on each axis solves the problem

In theory, the "real world" wouldn't see this bug as frequently, but I've submitted this bug report to The Foundry.

---

Response from The Foundry

Thanks very much for providing reproduction script, we can see the problem easily. Your comments and script are logged:

Bug 47417 - ParticleBounce - Leaks with static primitive geometry input in some cases

We recommend checking upcoming release notes for updates on this issue.