Forums Technical Discussion particle question: how to record secondary hits?

particle question: how to record secondary hits?

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Dougie0047
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Hi guys,
this might be an obviously stupid question to many of you, but:

for a particle rain sim, I have 2 objects - object 1 and 2(ground). Particles first hit object 1, creates bounces/splashes, then I generate streams of particles off that that slide down. Some of the sliding particles slide off object 1 and then hit object 2.

How can I detect exactly which object is getting hit? I've tried to use the pop collision detect node and entered a specific path to the sop geo collision target in there, but that does not seem to work. If I turn on the color hits I can see that every hit, not just the collision target is getting colored...

What I ultimately want is to have some of the dripping particles (from obj 1 to obj 2) create collision events from where I can generate secondary splashes. How can I do this?

Thanks,
Dag
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Enivob
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Joined: June 2008
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There are several hit attributes. (i@hitnum, @hittime)
https://www.sidefx.com/docs/houdini/nodes/dop/popcollisiondetect.html [www.sidefx.com]

Inside a popwrangle, try changing the color based on how many times a hit has occurred.
if(i@hitnum>4){v@Cd = set(1,1,0);}
if(i@hitnum>10){
v@Cd = set(0,1,0);
i@group_green = 1;
}
You could also add them to groups which could be used to spawn another stream.
https://www.sidefx.com/tutorials/particle-streams-1/ [www.sidefx.com]
Edited by Enivob - March 2, 2024 17:57:43
Using Houdini Indie 20.0
Windows 11 64GB Ryzen 16 core.
nVidia 3050RTX 8BG RAM.
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