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bigwil357

Letter Rising from Sand/grains COLLISION issues

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Hello!

 

I have recently been offered my FIRST FX job! I am familiar with Maya, and some Max, but this job requires that i use Houdini, so now i am all in! VERY EXCITED!!!

I have a scene where i have to make some letters rise from sand. The issue is that i cannot get things to collide correctly. Doing my research i have tried using it as a RBD object, and using a trail sop to computer its velocity, but i still dont see any collisions. I use static object, pointing to a VDB smooth as the proxy geo, and all of the collision detection/mode set to volume, but no collisions still. I set the sim up with an initial state file too. Could that be the issue?

 

When i take away the VDB to polygons and VDB smooth, delete and just run the sim as a regular static object, everything works! But...i get some weird artifacts rendering. What is the best approach to this method in Houdini? Im sure the solution is just a setting away, but im lost here. Any suggestions?

LetterSetup_001_collProbs.hip

ColisionProblems01.jpg

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So i just realizes that the artifacts are coming from the rising letter, reacting to the groundplane, stretching over it. It pishes the groundplane up, like its cloth. Is this correct? Do i need to figure out how to stop the letter from colliding with the plane, or is this correct, and i just have to hide the groundplane geo? I didnt even know that was possible! 

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Posted (edited)

I see a couple of things happening. You have based your grain generation off of the proxy mesh for the ground plane. It is better to dedicate a unique object for this. Also I noticed that the points coming into the point deform have a count mis-match. This is due to the fact that when OpenCL is enabled, it generatsd a different amount of particles, compared to the CPU rest version. Tun Off OpenCL to reestablish the match.

Basically you don't need the point deform version after making these modifications. But it could be used as a secondary material element.

letters.gif

ap_LetterSetup_001_collProbs.hiplc

Edited by Atom
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On 4/21/2019 at 2:55 PM, Atom said:

I see a couple of things happening. You have based your grain generation off of the proxy mesh for the ground plane. It is better to dedicate a unique object for this. Also I noticed that the points coming into the point deform have a count mis-match. This is due to the fact that when OpenCL is enabled, it generatsd a different amount of particles, compared to the CPU rest version. Tun Off OpenCL to reestablish the match.

Basically you don't need the point deform version after making these modifications. But it could be used as a secondary material element.

letters.gif

ap_LetterSetup_001_collProbs.hiplc

Thank you so much for your reply! I believed that i figured out the issue! I had NO IDEA about the open CL stuff. Theres a ton to learn in this amazing program, and i look forward to creating more! Thanks again!

 

 

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