How to Create Wetmaps Using COPs in Houdini 20.5

[@evanrudefx]

Thanks, I am actually working on a Copernicus wetmap solver too. I don't know opencl, so in my method I used wrangle cop with volume sample. but I got some ideas from this that I will implement. I am also working on dissipation. Thanks!

[@InsideTheMindSpace]

You can create dissipation with this method as well. Just multiply your volume by a value less than 1. I tried some other methods for creating a wetmap solver and there were some issues I ran into. Best of luck to you though

[@evanrudefx]

​@@InsideTheMindSpace Thanks for the reply. I got my setup working. I added the ability to control at what age dissipation will begin, because I wanted it to be "wet" for like 30 frames before starting to dissipate. And if the voxel becomes "wet" again that resets the 30 frame window. I did notice some odd results if there are lots of seams on the uvs. I tried using smooth fill and extrapolate boundaries, that seemed to help.

[@cms2582]

@@evanrudefx Hey, love your tutorials, I'd really like to know your setup for the wetmap dissipation in COPs! I got mine working by multiplying the volume by

[@evanrudefx]

​@@cms2582 I do plan to eventually upload that setup on my channel hopefully.

[@stereographik]

Perfect , exactly what i needed to get VDB into my COP. tnk u so much for sharing

[@InsideTheMindSpace]

Happy to help!

[@massimobaita7178]

Thank You very much!

[@Voodoo-b4f]

Thanks a lot for showing this. Any chance we could see, how to make the effect on a 3d model like in the intro?

[@InsideTheMindSpace]

The process is exactly the same. All I did was swap out the meshes and added gravity to the particles

[@apzzpa]

What are wet maps used for?

[@InsideTheMindSpace]

Whatever you can think of. You can use them for transition effects like shown. They are used for making materials seem wet when water splashes around over dry objects by controlling roughness.

[@rakeshmalik5385]

In C#, C++, and Java (because C# and Java copied the C++ version) the '&' on a parameter tells the compiler to bind it as a reference rather than by value. Or in other words, it's sets the parameter value to be the memory address that it's coming from instead of a copy of the data. As far as I can tell, OpenCL is also a call by value language, which means that without the ampersand the dst variable here does the same thing, allowing you to modify the dst value in the COP context from within the OpenCL node.

[@InsideTheMindSpace]

Thats a good explanation. Thank you. I refreshed my memory after recording this and you are correct. The ampersand specifies that the layer is write able. I like the extra information you provided as well.

[@rakeshmalik5385]

@@InsideTheMindSpace No problem :) I'm an escaping programmer... I used to have to know this stuff for work :)

[@thehomedepothouseplant9986]

Very cool!