What would be the best way to achieve these stains on a material?

[narroby]

Hello! I'm pretty new to Corona and 3DS max in general, and I'm struggling to figure out what the best way to achieve these marks could be.



With my limited experience I was thinking maybe utilizing Decals, but that option feels clunky. Alternatively, maybe some sort of Corona Composite material (but how do you make sure its placed on the edge?), or a maybe a CoronalDistance map with a grunge distance mask.

Does anyone know a better way to replicate these? Thank you!

[romullus]

Hi,

Why do you think Corona decals are clunky? Now when they got support of real-wold mapping, i think it could be one of the better options for this kind of job. Alternatively you could use your mentioned Corona distance, or Corona AO with z offset. Even old fashioned way through mapping with multiple channels is still workable solution.

[narroby]

Hello Romullus, thanks for the reply. I was actually just reading your reply on this ( https://forum.corona-renderer.com/index.php?topic=31552.0 ) similar post from a few years ago, which was very helpful.

The reason why I thought decals were not ideal for the job is because I wasn't able to figure out how to make them tile the material that's applied to them. Whenever I resize the decal, it stretches the bitmap as opposed to tiling like a regular material. Is that the way they actually work, or am I messing it up somehow?

Thank you!

[romullus]

In Corona 11 decals now can have real-world mapping enabled, so texture stretching is not an issue anymore. Assuming that your leakage texture is tiling horizontally, you can adjust decal's length as much as you want and the texture won't stretch, but instead will be tiled nicely. Decals can be problematic on highly curved surfaces, but on flat walls they work perfectly.

[maru]

As Romullus mentioned, this kind of effect can also be created using Corona AO or Distance maps:
https://docs.chaos.com/display/CRMAX/Corona+AO+Map
https://docs.chaos.com/display/CRMAX/Corona+Distance+Map

[John.McWaters]

In Corona 11 decals now can have real-world mapping enabled, so texture stretching is not an issue anymore. Assuming that your leakage texture is tiling horizontally, you can adjust decal's length as much as you want and the texture won't stretch, but instead will be tiled nicely. Decals can be problematic on highly curved surfaces, but on flat walls they work perfectly.

Hallelujah!