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Curve Texture Coordinates in Cycles and Eevee differ
Open, Confirmed, MediumPublic

Description

System Information
Operating system: Windows 10 64 bit
Graphics card: Nvidia GTX 750 Ti

Blender Version
Broken: blender-2.80.0-git.b3f96da2e605-windows64

Short description of error
The UV Texture Coordinates via the Texture Coordinate Node differ in Cycles and Eevee.
In particular, in Cycles, the coordinates are just 0, if "Use UV for mapping" is disabled in the curve data.
Eevee does not care whether this checkbox is enabled or not.

Also, I think the documentation for this checkbox is wrong: The tooltip says "Use the UV values as Generated texture coordinates."
However, it does not change the Generated texture coordinates, but the UV in Cycles.
I also don't know why anyone would ever disable the checkbox, since it just results in no UVs for Cycles.

Exact steps for others to reproduce the error


Top left: UV + Use UV for Mapping
Bottom left: UV
Top right: Generated + Use UV for Mapping
Bottom right: Generated
Cycles (2.79):

Cycles:

Eevee:

Details

Type
Bug

Event Timeline

Jacques Lucke (JacquesLucke) lowered the priority of this task from Needs Triage by Developer to Confirmed, Medium.May 27 2019, 2:21 PM

@Brecht Van Lommel (brecht) @Clément Foucault (fclem) you have to decide what the "correct" behavior is.

This is a legacy option I think, maybe it was useful to improve performance at one point but I doubt it has much impact now.

I think we can remove this option and always have it enabled.