Issue: Opacity suddenly changing with viewing angle


I’m trying to make translucent curtain material, but I keep on having an issue: If I view the material “head-on”, it’s very translucent (say, 30%), but if I change the viewing angle, at about 50 degrees, the opacity suddenly changes to about 90%. So when you walk around in the level the appearance of the material changes very drasticly depending on what angle you have towards it:

low viewing angle

slightly higher viewing angle


I’ve stripped down the complexity of the material to just the minimum, but the issue remains. Now I don’t know what more I can try…

Any help would be greatly appreciated!


I guess that the opacity isn’t changing but fresnel is boosting specular intensity at grazing angle. You can test that by plugging 0 to specular slot.

Specular = 0 does not change the behaviour.

I figure there is some connection with the Basic Lighting Questions in my other post: Switching off the Mobile Directional Light makes the issue go away. However, I’m unsure how sunlight could affect this surface: there are many other surfaces in between that should be blocking the sun.

Transparent objects use less precise shadowing. Maybe this is related to this. You can set size of transluency volume via command line.