On Jul 21, 7:07=A0am, Luc Moulinier <mou...@[EMAIL PROTECTED]
> wrote:
> Hi !
>
> I'm new to OpenGL, and even after reading tutorials ans manuals, I
> still get some troubles.
> I'm doing a simple molecular viewer. For simplicity, let's say a
> molecules are each a cloud of points, whose centers are not at 0.0 0.0
> 0.0.
> I'd like to rotate it , translate it, and center on any atom, using
> the mouse.
>
> 1) Rotations: by dragging mouse button-1 , the user rotates around the
> x and y axis. X is always horizontal, and Y is always vertical,
> whatever the rotation. This works well. Tcl/Tk code of the event
> binded routine :
>
> proc Handl***** {x y win} {
> =A0 =A0 =A0 =A0 =A0global cx cy
>
> =A0 =A0 =A0 =A0 set mvmatrix [tcl3dVector GLdouble 16]
> =A0 =A0 =A0 =A0 glGetDoublev GL_MODELVIEW_MATRIX $mvmatrix
> =A0 =A0 =A0 =A0 set mvList =A0 [tcl3dVectorToList $mvmatrix 16]
>
> =A0 =A0 =A0 =A0 glMatrixMode GL_MODELVIEW
> =A0 =A0 =A0 =A0 glRotatef $dy [lindex $mvList 0] [lindex $mvList 4]
[lind=
ex $mvList
> 8]
>
> =A0 =A0 =A0 =A0 glGetDoublev GL_MODELVIEW_MATRIX $mvmatrix
> =A0 =A0 =A0 =A0 set mvList =A0 [tcl3dVectorToList $mvmatrix 16]
> =A0 =A0 =A0 =A0 glRotatef $dx [lindex $mvList 1] [lindex $mvList 5]
[lind=
ex $mvList
> 9]
>
> =A0 =A0 =A0 =A0 set cx $x
> =A0 =A0 =A0 =A0 set cy $y
>
> =A0 =A0 =A0 =A0 $win postredisplay
> =A0 =A0 =A0 =A0return
>
> }
>
> 2) Translation : I can translate the objects, but when I apply a
> rotation, the rotation center is the old rotation center. I 'd like
> the rotation center to stay always the center of the scene, and
> objects spinning depending on translation.
>
> 3) centering: I handle picking and labelling of atoms using NameLists.
> I didn't succeed to define the center at the X,Y,Z of the picked
> point.
>
> I'm aware there is the gluLookAt function, but How do I retrieve the
> eye position ? I don't use gluLookAt at present in my app, so I don't
> know if the "eye" position has moved or not, or if it is still at 0.0
> 0.0 0.0
>
> I would be very gratfull to anybody who could help me !!
>
> Luc
For point 2), ensure the order is translate then rotate and the effect
will be ***ulative.
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