As the title says...
I have a transparent (glass or full transmission in the principled shader) plane, but I see the reflection of my area-light although the material is not reflective. The only way it disappears is when I set the IOR on the plane to 1, which defeats the purpose of my setup.
Any ideas? Bug?
-
3$\begingroup$ Glass is reflective. $\endgroup$ – user1853 Jun 4 '19 at 14:53
-
1$\begingroup$ Everything works like expected. You have set your glass to be perfectly reflective on the surface. That is what Roughness = 0 means. It is a perfect mirror surface with a glass volume behaviour. $\endgroup$ – BK. Jun 4 '19 at 17:22
According to the manual:
The Glass BSDF node is used to add a Glass-like shader mixing refraction and reflection at grazing angles. Glass BSDF
That's why you see reflections with this kind of shader.
If you don't need reflections on the object - use Refraction BSDF
-
$\begingroup$ Accepted...although I don't get why it happens with the Principled BSDF with Transmission Full and Specular off.... $\endgroup$ – knekke Jun 5 '19 at 6:32
-
$\begingroup$ Under the hood of Principled BSDF just mixing of other shaders. Example from Principled BSDF manual > Transmission is Mix between fully opaque surface at zero and fully glass like transmission at one. $\endgroup$ – RUben Jun 5 '19 at 8:26
All (smooth) surfaces in the real world become reflective at low angles of incidence, Eevee and cycles (with Principled shader) reproduce this, but Blender Render didn't.
As RUben says using a refraction BSDF will refract the light as if it entered a material of the same density of glass, without simulating the reflections that you would get when shining a light through real glass.