Backface to alpha

[YoyoBoy]

I'm wondering if there's a way to make the backfaces of a non-closed object render as transparent alpha. I'm finding that un-checking the 2-sided button doesn't do it, in fact it is causing the material to render brighter, though maybe that has something to do with being inside a Blend Material? But even if turning off 2-sided did work as expected, I want the backfaces to cut out any geometry behind them.

Thanks.

[Joelaff]

I know I have done this. It may have been a VRay2SidedMtl with no translucency (set that little square to black) and one side normal, but the other side a VRayMtlWarpper set to -1 alpha and Matte Surface/Affect Alpha.

Or maybe I used this https://github.com/gkmotu/OSL-Shader.../FrontBack.osl

I think there is a way with a VrayMtlWrapper. I just don't have time to test right now.

[hermit.crab]

I'm wondering if there's a way to make the backfaces of a non-closed object render as transparent alpha. I'm finding that un-checking the 2-sided button doesn't do it, in fact it is causing the material to render brighter, though maybe that has something to do with being inside a Blend Material? But even if turning off 2-sided did work as expected, I want the backfaces to cut out any geometry behind them.

Unchecking the Back material makes the shader use the Front for both front and back.

Otherwise, what Joelaff said should work. Since the VRayMtlWrapper will not affect shadows, the Alpha could be 0. Translucency in the VRay2SidedMtl should be off. Check the attached scene.