Backlight not working on Mac

[Brutha]

Hi All,

For some reason I can't get the backlight working in FreeCAD (not sure if I ever did in fact!): does anyone else have this issue?

There was a trick previously to get around it, by adding some lighting to the material appearance - but it doesn't seem possible in Arch using materials. It's a bit irritating to have surfaces go black as they get towards 90 degrees I find.

Any ideas?

Cheers

Brutha

Code: Select all

OS: macOS 10.15
Word size of FreeCAD: 64-bit
Version: 0.20.26155 (Git)
Build type: Release
Branch: master
Hash: 0926a4148bcff11249fd4f56bc30256102ffe105
Python version: 3.9.7
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.3
Locale: C/Default (C)

[wmayer]

Backlight is a global setting and doesn't depend on particular objects. You set it in the preferences under Viewer > 3D Viewer and there you should select another color than black.

[Brutha]

Backlight is a global setting and doesn't depend on particular objects. You set it in the preferences under Viewer > 3D Viewer and there you should select another color than black.

Thanks, indeed, this is what I have done, but to no avail - nothing seems to change. I have quit Freecad and restarted etc, but no results. This is my setting:

Screenshot 2021-10-24 at 11.30.21.png (14.78 KiB) Viewed 1469 times

There was a suggestion from someone in the past that as a workaround you could assign a material with a degree of luminosity to it, which did work, but this is not possible in Arch materials.

[Roy_043]

Are you aware that the Backlight color is used for the backside of faces? in other words you will not see this color when looking at solids from the outside.

[Brutha]

Are you aware that the Backlight color is used for the backside of faces? in other words you will not see this color when looking at solids from the outside.

Aha. I thought it was supposed to add some degree of "ambient" light. In the picture below, faces A and B are both the same material - I would like the lighting to be a bit more natural, and for face A to retain a more lifelike appearance even when viewed at close to 90 degrees.

Screenshot 2021-10-24 at 11.54.32.png (166.28 KiB) Viewed 1435 times

[Brutha]

Hmm, I think I should be able to add an "emissive colour" to the material, it is mentioned here: https://wiki.freecadweb.org/Material as property called EmissiveColor

I tried adding EmissiveColor as a property to the arch material, but it didn't seem to do anything. Any ideas?

[Roy_043]

See: https://forum.freecadweb.org/viewtopic. ... 10#p538977

[Brutha]

Thanks Roy, yes, that's what I'd used before, but when I tried changing the appearance for an Arch material, that button is greyed out and so you can't set an emissive colour.

BUT - I've realised that you can set the normal colour via the material, and add an emissive colour still for each object, so there is a workaround!

It's a bit of a pain though, since if you want to change it later you might have to do it for 100's of objects. It would be nice if all appearance stuff could be done on a material rather than object basis. And from my link above, it sounds like that was the idea anyway, since the property is mentioned in the wiki.

Perhaps I can anyway write a script for this.

[Roy_043]

Creating a script should be possible.

Code: Select all

App.ActiveDocument.Wall.ViewObject.ShapeMaterial.EmissiveColor = (0.5, 0.5, 0.5, 0.0)