the Comp node presents the 1st, 2nd or 3rd component from:

point in space (on surface) * value + pixel in image_map or so * colorswatch

1st component is either X or Red, 2nd is Y or Green, 3rd is Z or Blue.

from the default, it presents 0 as value = (0,0,0) and colorswatch = (0,0,0) too.

You can extract Green from a texture, but also height Y from a position to generate a height-dependant texture.

I agree that (1,1,1) should be more handy as a default for value as well as color, you can issue a call at SM.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though