If an object is drawn in IntelliCAD PE+ as a 3D ACIS object it can be rotated about its centre using the Real Time Sphere command (RTROT).
If the same object is then copied and the copied object is placed some distance from the original object the Real Time Sphere command (RTROT) rotates both objects about the centre of the two objects.
If you then delete one of the two objects how do you get the Real Time Sphere command (RTROT) to rotate from the centre of the now remaining single object because it seems to retain the centre point for the original two objects?
#2
geraldpeterrobinson,
Having spent way too much time investigating this dynamic rotation thing, I can say this : You need to set the origin of the UCS where you want the center of rotation to be. And, if you do this by picking geometry on-screen, the pick should be as close to the center of the display as possible. With these requirements in mind, I wrote the following lisp :
(defun sdr_error (msg)
(setq *error* sys_error)
(setvar "OSMODE" osval)
(setvar "cmdecho" 1)
(princ)
)
(defun c:sdr (/ pp)
(setq sys_error *error*)
(setq *error* sdr_error)
(setvar "cmdecho" 0)
(setq osval (getvar "OSMODE"))
(setvar "OSMODE" 512) ; set nearest snap
(setq pp (getpoint "\nPick Center of Rotation"))
(command ".ZOOM" "C" pp "")
(command ".UCS" "O" pp)
(setvar "OSMODE" osval)
(setvar "cmdecho" 1)
(redraw)
(setq *error* sys_error)
(princ)
)
This program will set the rotation center to any point you can pick on existing geometry. The only thing I don't like about it is that it moves the displayed image so the pick point is at the center of the viewport, which is not always what is wanted, but is, I think, necessary.
Your example with spheres would present a problem, in that there is no center of the sphere to snap to. If you create the sphere with a point at center, that would work.
For convenience, you could set an unused function key to call the lisp.
Having spent way too much time investigating this dynamic rotation thing, I can say this : You need to set the origin of the UCS where you want the center of rotation to be. And, if you do this by picking geometry on-screen, the pick should be as close to the center of the display as possible. With these requirements in mind, I wrote the following lisp :
(defun sdr_error (msg)
(setq *error* sys_error)
(setvar "OSMODE" osval)
(setvar "cmdecho" 1)
(princ)
)
(defun c:sdr (/ pp)
(setq sys_error *error*)
(setq *error* sdr_error)
(setvar "cmdecho" 0)
(setq osval (getvar "OSMODE"))
(setvar "OSMODE" 512) ; set nearest snap
(setq pp (getpoint "\nPick Center of Rotation"))
(command ".ZOOM" "C" pp "")
(command ".UCS" "O" pp)
(setvar "OSMODE" osval)
(setvar "cmdecho" 1)
(redraw)
(setq *error* sys_error)
(princ)
)
This program will set the rotation center to any point you can pick on existing geometry. The only thing I don't like about it is that it moves the displayed image so the pick point is at the center of the viewport, which is not always what is wanted, but is, I think, necessary.
Your example with spheres would present a problem, in that there is no center of the sphere to snap to. If you create the sphere with a point at center, that would work.
For convenience, you could set an unused function key to call the lisp.