Any idea how I could create a growing wet map based on contact of 2 objects. For example a liquid pouring in tunnel and when the liquid advances, the texture spread on the tunnel walls in time starting from the first contact. I know stoke MX2 can do wet map thinkboxsoftware.com/stoke-m … field-sim/
But how to make it grow over time based on contact?
Also it must not grow uniformly, but it should grow only after contact. for example a green liquid seen from top view would create a growing orange wet map like this:
The trick is to use a Stoke > Grid operator set to Relative mode and Relative Spacing > 1.0. This will resample the incoming channel on the larger grid and thus blur it a bit. On the next frame, that data will be resampled again and so on, and this will produce the gradual blurring you are after.
In the attached example, I created two channels:
*Wetmap collects the particle info and adds 1.0 to the channel if there are any particles, and subtracts 0.05 if there are no particles (to dry out). You can set the -0.05 to keep the wetness.
*Blurmap reads the Wetmap, blurs it though a Grid operator, and outputs into Blurmap again.
If you render the Blurmap, you will get the equivalent of what you showed as orange color in your example.
If you render the Wetmap, you will get the equivalent of the green part.
I also introduced a Reduction factor - the Blurmap gets divided on each frame by a value to fade off further. Below are some examples using different settings.
