Texture rotation not consistent between Rhino 5 and 6


was there a change in regards to the rotation of textures? The texture is rotated in the other direction in Rhino 6, compared to Rhino 5. Is this a bug in Rhino 6 or in Rhino 5 or intended behavior?

Repro: Open attached model in Rhino 5 and Rhino 6 and look at different texture in viewport.

But I get the same Texture.UvwTransform. Do I have to interpret the values differently in both versions?

texturerotation.3dm (407.0 KB)

@DavidEranen, wasn’t this a thing we tinkered with at some point? </vague_recollection>

Any news on this front?

Not much yet, but I seem to recall that the texture rotation was changed to be interpreted such that increasing the rotation (positive) is now clock-wise. I think that was done to be consistent with the mapping rotation on the groundplane, which is in v5 also clockwise for positive.

OK, sounds like it is intended behavior that the same file looks different between Rhino 5 and Rhino 6. If it is our goal to duplicate the look of the Rhino viewport, we must interpret the rotation depending on the Rhino version. Shall we adjust our code now or wait until you guys have finished your investigation? In the latter case, can you give a timeframe?

I am pretty sure there won’t be changes to this, it’d break existing v6 files. But if any changes are deemed necessary it probably won’t happen in at least the following 4-5 weeks, since it requires both Rendered mode and Raytraced agree - summer holidays start today