The purpose of this memo is to document and provide an explanation for some "strange" behavior.
If you do: load caffeine.xyz; set perspectiveDepth off; set windowCentered off; set picking center; Then, click on atoms You will see a very slow migration of the molecule towards the upper left. The atom that is the new center stays in the same position. Of the other atoms, a random sampling of half move up one pixel. Independently, a random sampling of half move left one pixel. The source of this problem is as follows: Transformations are performed in floating point ... but screen coordinates are stored in integer coordinates. When we set the new center we "reverse" the screen coordinate to try to figure out the new transformation for the new center of rotation. We are preserving the pixel location of the new atom center ... as truncated down to the nearest integer. But that makes some other atoms move. I believe that we can correct (or minimize) this problem by re-transforming the atom coordinates of the new center and using the floating point values (rather than the integer screen values) to feed into the calculations. Miguel ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid0944&bid$1720&dat1642 _______________________________________________ Jmol-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jmol-developers
