Custom Simulations In Vop Sops And Cops

[ofer]

Hello!

Im searching for a way to implement some real-time CG techniques in houdini.

I want to try a simple water simulation to start. I started with the article from "Game Programming Gems".

With SOPs, the method requires me to store the mesh from the previous frame, and the current frame, to derive the next frame's mesh. Couldn't think a way to do that.

I looked in COPs, but couldn't find a way to sample neighbour pixels, or to sample a 2D texture. SO I can't take a texture based approch.

I will try to come up with a math+trig based solution, but being able to create some simple grid-based simulations is always helpful.

Any suggestions?

[MADjestic]

Hi, ofer

this topic is being brought up from time to time, there are at least 3 people here who have implemented this algorithm in Houdini (partially or not).

Try the following links for related discussions:

http://forums.odforce.net/index.php?showtopic=3332&st=24

http://forums.odforce.net/index.php?showtopic=4804&hl=

[ofer]

Thanks! Thats not what I was talking about, but I was searching for this voxel thread for some time.

Anyway, I think I thought of a way to create a simulation with COPs, and I realized I forgot about the SOP solver in DOPs, so that might be the way to go with SOPs.

I prefer COPs, since I its more scaleable. I think I can do neighbour sampling using four transform COPs and then inputing them into my VOP COP, and to use expressions in the file name in a File COP to use a texture from the previous time step.

Ill try it.

EDIT: I found the 'Cop Input' COP. That is what I was looking for.

Edited April 22, 2007 by ofer

[stabby]

Hey,

Check out the convolve COP for your neighbour sampling needs. It's easy and efficient.

[ofer]

OK, I will. Thanks.

I finished my simulation. It works well, but I had to use an hscript to render it. I'll post the results when I finish tweaking the params.

[mattd]

I have been thinking of a solution to this using CHOPS when I was using Touch a while ago, I never got past how to do a convolve on all the channels coming from a geometry CHOP, but I do know H better these days, and I will give it another go soon...

I know there is a way to achive this at realtime speeds, the first time I ever saw this algorithm in action was the old irisGL demos on a indigo running at 150 Mhz

MD