Hi,

I'm trying to get shadows from the VEX Global Illumination shader on a Light Template. All the objects on the scene have the shadowmatte material assigned, but when I click on render all I get is black, there's no shadow information whatsoever.

lonrot
Hi,

I'm trying to get shadows from the VEX Global Illumination shader on a Light Template. All the objects on the scene have the shadowmatte material assigned, but when I click on render all I get is black, there's no shadow information whatsoever.

Shadowmatte shader puts your shadows into alpha channel, but occlusion isn't technically a shadow, so it won't be seen in alpha either. Reversing occlusion amount (1-occlusion) as the only surface illumination makes what shadowmatte does with standard shadows.

Got a little bit lost here, so isn't there a way to render only the shadow coming from the ambient light, or occlusion as you said?

lonrot
Got a little bit lost here, so isn't there a way to render only the shadow coming from the ambient light, or occlusion as you said?

There is! It would be a plain occlusion without any other contributions (diff, spec, etc). You can render it separately or as a deep raster. The point is that your shaders need to be built this way, or you'll have to overwrite them for all objects in a scene. In productions, where there are hundreds of objects, possible inside closed assets, this is quite inconvenient. There is also third option to use python IFD filtering, but that's yet another topic.

See example file.

hth,
skk.

ps I inverted occlusion to match what shadowmatte is doing, and what usually compositors prefer to work with, but it's totally optional.

Thanks SYmek!