In this example we use an image of 1px wide, with the color for grazing angles at the bottom, and the color for normal angles at the top.
- UV transform:
- R.Z = 180°.
- (S.X, S.Y) = (0.5, 0.5)
- (T.X, T.Y) = (0, -0.25)
- Use spherical projection and set coordinate space to "Normal space"
- Set border mode to "Clamp value"
You can change the rotation according to the orientation of the image. If your image contains the ramp along the X axis, use 90° or -90°.
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Roeland