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Issue with Opacity Maps
Posted: Mon Sep 24, 2012 5:58 pm
by derekjackson
Hi,
I'm trying to use the opacity map slot to create a simple perforated metal sheet material.
I've started with a basic standard rough metal material (so two initial BSDF layers set to 80 and 20).
Adding the opacity map to each layer doesn't seem to affect anything - the preview is the same as a solid metal material.
Opening up a ready-made clipmap material works fine, but I can't see any key differences between the settings. Is there something obvious I'm missing? Is it a known bug?
Could I need to place a 'transparent material' layer below the two metal layers?
I'm using 1.7.1.
Any help appreciated!
Thanks,
Derek
Re: Issue with Opacity Maps
Posted: Mon Sep 24, 2012 6:26 pm
by Bubbaloo
Post a link to the material, and I (or someone else) can see what's going on and help.
Did you mean 1.7.1 or 2.7.1?
Re: Issue with Opacity Maps
Posted: Tue Sep 25, 2012 6:36 am
by pipcleo
make sure nd =1
Re: Issue with Opacity Maps
Posted: Tue Sep 25, 2012 9:47 am
by derekjackson
Yep, I meant 1.7.1.
Changing the Nd to 1 has no effect.
Files can be downloaded here, along with a screengrab:
https://lsiarchitects.sharefile.com/d/s2d3960514b243c3b
Any thoughts?
Re: Issue with Opacity Maps
Posted: Tue Sep 25, 2012 10:00 am
by Fernando Tella
It could be that the UVW mapping in the preview doesn't show your map. Have you tried a different preview scene?
Re: Issue with Opacity Maps
Posted: Tue Sep 25, 2012 10:03 am
by JDHill
The links don't work for me, but try this: create a new material and add two BSDFs. In the first BSDF, set Transmittance to white, Nd to 1.0, and put your clip map in the Blending Weight channel. In the second BSDF, set Reflectance 0° to red, put your clip map in the Blending Weight channel, and check Invert Texture in the texture editor. If you refresh the material preview, you should now have a red clip-mapped material. The first BSDF represents a vacuum, and you map it across the surface of your objects using the pattern of your weight map. The second BSDF represents your material, and you map that using the same texture, but inverted.
Re: Issue with Opacity Maps
Posted: Tue Sep 25, 2012 10:30 am
by derekjackson
Okay,
that's weird. Starting a new material worked fine, but couldn't get it to work for a preset.
I tried then tried adding a vacuum layer to my metal and it showed as black instead of transparent. Then I changed the vacuum layer's reflectance to white, and it became transparent. I then changed it back to black, and it stayed transparent. Definitely looks like a bug rather than anything I was doing wrong?
Think we're there now but no idea what made the difference.
Thanks for the help everyone.