centr of rotation/centering
- From: Luc Moulinier <moumou@xxxxxxxxxxxxxxxxxx>
- Date: Mon, 21 Jul 2008 06:07:08 -0700 (PDT)
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 HandleRot {x y win} {
global cx cy
set mvmatrix [tcl3dVector GLdouble 16]
glGetDoublev GL_MODELVIEW_MATRIX $mvmatrix
set mvList [tcl3dVectorToList $mvmatrix 16]
glMatrixMode GL_MODELVIEW
glRotatef $dy [lindex $mvList 0] [lindex $mvList 4] [lindex $mvList
8]
glGetDoublev GL_MODELVIEW_MATRIX $mvmatrix
set mvList [tcl3dVectorToList $mvmatrix 16]
glRotatef $dx [lindex $mvList 1] [lindex $mvList 5] [lindex $mvList
9]
set cx $x
set cy $y
$win postredisplay
return
}
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
.
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