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Vector Curves node incorrect output after changing clip range
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System Information
Operating system: Windows 10
Graphics card: GTX 1080 Ti

Blender Version
Broken: 2.80 2018-11-30 4c31bed6b46 as found on splash screen

Short description of error
When you change the clipping range from -1 to 1 to 0 to 1, the output values no longer match the values shown in the UI.

Exact steps for others to reproduce the error

Based on default file (or see attached before / after blend flies:

  • Use nodes to create a shader for default cube
  • Add a vector curves node
  • Connect it to color output (just used as an example)
  • Press the [•] button to change the clipping to between 0.0 and 1.0 on X and Y axes
  • In Vector Curves dropdown menu, Reset View
  • Click in one of the X or Y text fields at the bottom of Vector curves to "kick" it and cause it to update
  • Cube no longer interpolates between black and white, but 50% grey and white



Event Timeline

I'm guessing this is because some colorspace math happening. I suggest that you use the "RGB curves" node instead so that you use nodes that has the correct node outputs.
@Brecht Van Lommel (brecht) is this an issue or just incorrect use of the nodes?

Brecht Van Lommel (brecht) triaged this task as Normal priority.Dec 11 2018, 6:55 PM

There is no color space math involved here. It seems to work in Cycles, I think there's just no correct support for clipping in Eevee / GLSL.