I have a small collection of planar surfaces placed in the same plane. They are all set to display colour = “By Layer” and are on the same layer. However they are coloured differently:
This is unhelpful if you have a lot of layers and need to distinguish them by close colours…
Inconsistent By Layer Colour.3dm (187.7 KB)
I think you have your display mode set to color backfaces differently. And by coincidence it’s almost the same purple color as the layer color…
My backfaces are set to color red, this is what I see:
Thanks Mitch - great call. Although the backface is per default, i.e. set to use front face settings. That does cause the slight shade change.
Moral of the story: check normals on borrowed geometry!
Jeremy
Hmm. not seeing that here, this is what I get when I turn off backface coloring (i.e. use front face settings).
Yes - I can discern a difference in your image. And using an image editor pipette I get two RGB values:
Yep, you’re right, it is a subtle difference but it’s there.
Hi Everyone,
I still have this problem even though I have “Color Backfaces” turned off under “Object Settings”. I am primarily working in Grasshopper and this problem also occurs for the previewed GH geometry. It also occurs after this geometry is baked into Rhino. Any ideas? I have checked that no surfaces are overlapping.
Best,
Grant
Hi Grant,
Please post a .3dm file with these surfaces.
Regards
Jeremy
Sure! Here’s a 3dm file with some of the surfaces shown in the pictures above.
Surfaces.3dm (165.6 KB)
Hi Grant,
Your surfaces are not all oriented the same way, some are showing their front face, some their back face:
Even if you select “Use object colour” for backfaces in the view settings, Rhino will still use a very slightly different shade to distinguish front from back.
If it matters, you can get the surfaces to look the same by applying appropriate 180 degree rotations to bring them into the same orientation. You could also flip the normals, but that would leave different uv directions which might make life difficult later, e.g. in applying materials.
HTH
Jeremy
Hi Jeremy,
Thanks for the help! I thought I already checked that but evidently not 
I didn’t know the tidbit about the slight color difference even with backface color off, so thanks for that. Your discussion above makes more sense to me now.
I still encounter some weird bug in Grasshopper though. I’ve taken all the surfaces and flipped them based on a guide surface, but still get some discolored surfaces. If I bake these surfaces, they no longer have the color problem, and you can now see that they are oriented the same way (although not necessary with local x and y directions). If I reference these surfaces back into grasshopper, they no longer have the color issue. This isn’t a big problem, but I’m just a bit curious. Maybe it has something to do with how grasshopper is optimized under the hood and referencing geometry from previous components.
Best,
Grant
It’s an old bug in Rhino that occurs even if the backfaces are set to use the same settings as the front ones.
