Unreal 4, Alpha map troubleshooting.

ozzy310 · May 2017

I have an alpha map that I'm using for my window pane. When importing to unreal I know you're suppose to set the materials under blend mode to masked then plug in the alpha map to opacity mask. It works, it makes the window pane transparent, but I want to make it 50% transparent instead of being 100% so you can see a bit of color and stains. I can't figure out how to make that happen is there something I'm missing or is there another way of doing it?

Joopson · May 2017

So, the masked blend mode is either on or off. 0 or 1. Along with the opacity mask input.

If you want 50% transparency, I believe the blend mode must be set to translucent, and the mask should be plugged into opacity, not opacity mask.

ozzy310 · May 2017

You mean I didn't place the masked on blend mode?

I did place the blend mode on translucent then the mask plugged into opacity which works it displays at 40% but it also affects the rest of the mesh. Unless I'm not suppose to have the window pane grouped together with the rest of the mesh. I figured it wouldn't matter considering were masking the alpha map.

Below: Using masked on blend mode. Which works but I want the transparency to be at 40% at least to what I have painted on my alpha map.

Below:

Left: Translucent mode on. Right:Masked mode on.

Obscura · May 2017

First of all, the translucent parts should be a separated material, so you make sure, this sorting issue won't happen. Also this way you minimize the translucent area, so you reduce shader complexity as well.

To me it look like there is something wrong with the alpha texture itself.

Lets see how that alpha actually looks like. Open up the texture, in Unreal, and on the top left corner, yo can include, exclude channels. show us the alpha.

ozzy310 · May 2017

Everything within the red circles are black except for the windows which are about 70% black enough to see some speck and color for the glass. Other than that the rest of the map is white. I tried messing about with different controls and the result tends to be either full transparency or non. I'm thinking of just extracting the single plane in order to get the right transparency that I want.

I have also been saving it in targas, 32-bit. I have tried PNG but get the same results.

Obscura · May 2017

There is "view" on the top left corner of the texture. Open that, end disable everything, except alpha, and show that. From this image, its not clear how are the values in it. It seems like you have a plain white alpha channel.

ozzy310 · May 2017

Obscura · May 2017

So its good. I was taking an another careful look on your image because its still not fully clear how this would be. I don't see the point of expensive transparency on this, but ok. Now add that extra material to those polygons, that needs to be translucent, and try again. I think it works like you want it to, but you have a lot of transparency sorting errors because its not separated, so its confusing af.

Obscura · May 2017

Also, technically you would need 2 extra materials... One for the translucent glass parts and one for masked material on the leaves or anything with 0-1 opacity (not shades of gray).

ozzy310 · May 2017

Thanks, I appreciate you taking some time on this. You clarified some things for me.

Unreal 4, Alpha map troubleshooting.

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