Maya mental ray ao that only shows up in ambient light?

malcolm

Is this possible in maya, I'd like my ao shader to only show up in the ambient light's contribution, ie you shouldn't really ever see ao where the directional light is hitting but rather just in its shadows, multiplying it on top of the directional light looks kind of gross and muddy to me. Ideally I'd like to avoid using a bunch of render layer stuff and find some way of getting this working in the light shader. I found a description that works in max but we can't turn point lights into true ambient lights in maya so I'm out of luck. If you plug your mib_amb_occlude node into the light shader slot of your ambient it will only show the ao shading in the shadows but this makes your ambient light positional which is annoying. Now that I think about it this should be pretty easy to do with render layers by rendering out a mask of the shadows and applying that to the ao layer. I'd way rather just turn this on in the lighting some how and have it work.

rebb

Yes it is, made a tiny-tut - hope it makes sense - tired.
( Hint : Follow the red dots )

malcolm

Hey rebb that's a nifty trick, unfortunately you can't control the colour of the area light once you've set it up this way. I found changing the ao shader to be blue to try and work as the ambient light yielded some weird results.

rebb

Hmm, setting the Bright-Color of the AO Node seems to work ok here. Are there any particular settings that yield the weird results ?

malcolm

A friend at work has shown me how to do this. You need to use a surfillum maya node to tell the ao shader to only show up in the shadowed areas. Really nifty for tuning your light rig right in the render view instead of having to composite it later. If anyone wants to work this way let me know and I'll post the shading network for others to use.