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Color ramp HSV, Far-mode have wrong behavior
Closed, ResolvedPublic


Cycles, material node editor, RGB-
Blender Version
Broken: 2.78

As you can see.
The first: when I move H to 1, it become`s zero. Ok, I know HSV is circle and it is the same. But still not useful.
But it would be nice if the last H will be not 0=1, but 0.999

CW or CCW modes have correct behavior, because it is impossible to say where 1 from 1, left or right.
Far mode should go the longest way: all around the HSV-circle. And it should looks like this:

For now the solution is set 0.999 on the left color node manually.
idk, may be it is not a bug of Blender, but misunderstanding of Far-mode.

Event Timeline

Vyacheslav (hitrpr) updated the task description. (Show Details)
Bastien Montagne (mont29) triaged this task as Normal priority.

This is partly a limitation of how colours are picked and stored in Blender as RGB values. This means that when selecting a red with a Hue of 0 or 1 it is converted to the same RGB value which is what is stored, The hue value used in the ramp is determined from an RGB to HSL/V conversion. A potential fix for this would mean adding the ability to store Hue values when selecting colours which would result in the correct interpolation.

The following patch changes the behaviour of the FAR mode to force interpolation if the hues are the same. The direction is set to CW in this case. This also means that you wouldn't be able to set an area of the same colour.

Still the same problem. Far is not far-around.

Did you apply the patch? This is just a suggested fix and this bug probably needs reviewing by the UI team.

Okay, I see. Thanks.

Thanks for the patch, added a review about that change (and fixed original patch that had some issues in some cases, e.g. with two stops on red and blue, would generate 1.6666 turn into the hue space ;) ).