View Full Version : Decal on windscreen

01-17-2018, 11:08 AM
I want to Place a decal on a car windscreen. The glass has to be some transparente. But the problem is the decal also get transparent. What shall I do to get it right independent of the glass tranparency?

01-17-2018, 01:02 PM
Material Mixer.

One material is the glass, the other material is the decal, then mix using the alpha for the decal to mix the two.

01-17-2018, 01:33 PM
I have both image and alpha. But when I rise the transparency of the glass, the decal disappear.

01-17-2018, 01:47 PM
How are you mapping the decal to the windscreen? If you're using an Image Map of some sort (like a UV Map), you can use the Alpha channel of the decal as a Subtractive Image Map on the Transparency Channel. You may need to clone the decal image in the Image Editor (F6=>Clone=>Instance), set the cloned instance's Alpha Channel to "Alpha Only", and use the cloned instance on the Transparency channel.

A quick sample scene attached. The windscreen has the Fast Fresnel shader applied. I used a UV Map to place the decal by selecting the polygons in Modeler for that corner, creating an X planar UV map, then shifting the polygons in the UV Texture view to position the decal where I wanted. I didn't fine-tune the points to eliminate the slight disfiguring of the decal, and there may be a better way to model the windscreen for the purpose of UV mapping that section.

139538 139539

Here are the setups for the Color channel and the Transparency channel:

139540 139541

As well, I copied the Transparency layer to the Reflective channel to make the decal not as reflective as the glass.


01-17-2018, 06:30 PM
Thanks for Your quick reply. When I load mine images into Your scene, the white background is still there. When I open the Image Editor I see something strange. Loading Your image the ALPHA CHANNEL is enabled. Loading mine the Alpha Channel is ghosted - locked. Why ? See the Attached file.

01-17-2018, 10:17 PM
OK, the difference is that my image is a 32-bit Targa file: 24-bits of Red, Green and Blue color (8 bits per color) with 8 bits of Alpha channel. You have a separate file, called lategreat_alpha.jpg which only contains the greyscale Alpha channel, white being completely opaque, black being completely transparent. The control to enable or disable the Alpha channel is only applicable to 32-bit images where the Alpha channel is included in the same file.

I still don't know the details of how you map the decal Color image to the windscreen. Are you using Layers (Surface editor), or Materials (Node editor)?

If it's Layers, you should be able to get into the Color Texture (the "T" button) and Copy Selected Layer on the layer containing the Color image. Go into the Transparency Texture (again, the "T" button next to the Transparency channel), and use Paste=>Replace All Layers. Then, replace the image for the Layer with your lategreat_alpha.jpg image, set the Blending Mode to Subtractive, and your decal *should* be opaque while the windscreen is transparent.

Hope it helps!


01-19-2018, 09:17 AM
What would be the procedure if doing this in LW2018?

01-20-2018, 05:56 AM
Thanks so much, MP. Now I understand it. Regards Bjorn