New PBR alpha channel slot in latest Wip

Pbr materials have a VERY powerful opacity system which allows you to do things like stained glass and other complex effects.

BUT… this comes at a price where the age old method of using an opacity map to make “holes” in stuff got very complicated. (base color has to be WHITE where it’s transparent, then opacity has to be BLACK where it’s to be mapped out, HOWEVER… that only makes for “clear glass” not a true hole.But if you color the White bits, then you can get colored transparency, which is amazing…) This was making me straight up mental as I was trying to make a vent panel.

Andy and his crew just made a small but lovely addition to the pbr material settings which fixes this and gives us all the ability to make “holes” in materials. Simply add a black and white image in the new Alpha slot, and >poof< holes!

small bug is being addressed where the alpha percentage is not respected in ray traced mode. Will be fixed asap.

Give it a go!

you weird users. Just create your textures properly!



From my point of view the left sand path is what I’d want to write, and right is what you want - more complications :slight_smile:

likely… and that’s why we’d both be “wrong” in any given situation… so we get both and ultimately more freedom to create…which is the whole point of all of this!

Thanks to you and the Mcfin crew for the work on this!

So, just to be clear, (haha got it?)

If you want glass transparency = Opacity channel
If you want Holes = Alpha Channel


Alpha is a brute force tool for making holes (fences, vents, grill meshes) , and opacity is a nuanced tool for affecting not only opacity, but color of the opacity. (stained glass, milky glass, colored glass, mottled glass etc…)

Instead of opacity you can think the word transmission (but inverted values from opacity).

Yes - this easiest way to think of the difference between Alpha and Opacity is this…

Imagine a piece of glass with holes in it. The glass is “transparent” - you can see through it, but it might be coloured, it might bend the light (refract). But light goes through.

The holes are “alpha” in the texture. They are just not there - the surface is actually missing at that point. You could, of course, also model this - make real holes in the surface…but sometimes it’s easier to do it with a texture.