Talk:Turn

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Revision as of 16:44, 7 December 2010 by SavinaRoja (talk | contribs) (Incongruity between article and implementation?)
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Is there an inconsistency between this article and the actual implementation of Turn in PyMOL? Reading this article gives the impression that the camera rotates about its axes at its origin in camera space. If this were true, an issued command such as "cmd.turn('y',180)" should actually move an object placed before the camera (perhaps centered with its position in +z, for instance) to a position *behind* the camera (-z). In practice, that is not what I observe. Instead the object of interest appears to rotate about its own central axes.

I have posted here: [1] An example of view matrix alteration produced by Turn, in this case a 180 degree rotation about the y-axis.

To me it seems that what it actually being effected is the alteration of the relationship between model and camera spaces rather than applying a rotation matrix to the object coordinates in camera space.

My recollection of the involved mathematics is a bit vague, but these are relatively intuitive concepts of notable distinction. I'll brush up on the math, but I think the problem lies with a misunderstanding of PyMOL's workings or a lingual inaccuracy of the article. I am relatively new to PyMOL and only recently have started peering inside its source code. Perhaps my understanding of its workings is flawed? If so I hope some discussion can help inform how to improve the PyMOLWiki.

--SavinaRoja 20:44, 7 December 2010 (UTC)