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I was recently working on a node setup the required for some color image data to have some negative values, as I was using the subtract node. As far as I can tell, the values stop being subtracted at 0 though, and just flatten out. I turned clamping off on all of the nodes too. Would a good (but slightly painful) work around be to separate the R, the G and the B values into value data instead of color?

Please site a manual source if possible.

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  • $\begingroup$ It works for me..? $\endgroup$ – gandalf3 Dec 3 '15 at 6:44
  • $\begingroup$ I think your suggestion to split the channels into value data would be better regardless of whether this might work - colors aren't meant to be negative, since such a thing doesn't really exist. It would therefore also just be more transparent if you were to separate the values. You could, I guess, work with a Point3 or Point4 value instead, if you really want to perform operations on all three or four channels at once. $\endgroup$ – MaVCArt Dec 3 '15 at 13:34
  • $\begingroup$ @gandalf3 Yes, but this one is going through a bunch of MixRGB nodes set to various values, and is being used in the world material. I think something is chopping the values. $\endgroup$ – GiantCowFilms Dec 3 '15 at 15:05
  • $\begingroup$ @GiantCowFilms without seeing the structure of your nodes, the best I can guess is that the mixRGB operation is performing an operation that requires the values to be within RGB range, being 0-255. Could you try splitting up the values / using a Point3 and see if that changes anything? $\endgroup$ – MaVCArt Dec 3 '15 at 15:09
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    $\begingroup$ @MaVCArt I conducted a quick test, and the negative values do in fact appear to be working, something else in the node tree was throwing me off. $\endgroup$ – GiantCowFilms Dec 3 '15 at 15:15

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