Hi,
There seems to exist a problem with the material ID channel using Mix materials.
The problem is that unlike with a single material, when using a mix material (with 50% mix of 2 materials with opacity channels) the corresponding material ID channel is 100% opaque. This is a problem when dealing with, for instance leaves on a tree, or just about any placard based render with the material colour multipass.
In fear I have not adequately explained the problem, I have attached a graphic to show exactly what I am talking about...
Kind Regards.
Bug? Mix material with opacity...
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JessicaVines
- Posts: 69
- Joined: Thu May 08, 2014 7:52 am
bump, surely someone has experienced this before? Seems to be a show stopper for using ID matte with mix materials!
When you render the material ID info channel, you are only seeing the material ID. The material is not evaluated with the exception of opacity. The mix material itself doesn't have an opacity channel and mixing material ID colours doesn't make any sense either, which is why it's rendered opaque using the material ID of the mix material. So it's not a bug, but a limitation of how things are designed right now.
In theory there is no difference between theory and practice. In practice there is. - Yogi Berra
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JessicaVines
- Posts: 69
- Joined: Thu May 08, 2014 7:52 am
Understood, thanks for clearing that up.
It would be nice if we had the option to use object A or B's opacity channel as the mix material. Or even better if this channel was mixed in the calculation also. At the moment the only solution it seems is to render another pass with object A/B instead of the mix to extract the mat ID.
One other problem I have encountered is that objects invisible to camera still registers in the mat ID pass.
Thanks.
It would be nice if we had the option to use object A or B's opacity channel as the mix material. Or even better if this channel was mixed in the calculation also. At the moment the only solution it seems is to render another pass with object A/B instead of the mix to extract the mat ID.
One other problem I have encountered is that objects invisible to camera still registers in the mat ID pass.
Thanks.