[vtkusers] Need help integrating VTK with an existing OpenGL application (translating glFrustum and gluLookAt calls to VTK)

[Mark Waligora]

Weiguang,

Thanks for the reply.  I have no problem using the vtk classes in place of
code that I already have.  My issue is that I'm not certain how to use the
vtkCamera in place of my glFrustum call when I am creating a frustum where,
for example, both the left and right sides of the front face of the frustum
volume lie on the negative side of the y axis.  From what I can tell, the
vtkCamera can be given a viewing angle and a near and far plane, but that
gives me the equivalent control of a gluPerspective call, which is more
limited than the functionality that glFrustum provides.  I noticed there was
a function to multiply in additional matrices to the camera's transformation
matrix, but I don't think that would be quite what I want either.

-Mark Waligora

On Jan 3, 2008 1:08 PM, Weiguang Guan <guanw at rhpcs.mcmaster.ca> wrote:

> Hi Mark,
>
> If you decide to move on to vtk, then you shouldn't called gl commands
> directly. vtkCamera contains methods that implement what you want to do.
>
> Weiguang
>
> On Thu, 3 Jan 2008, Mark Waligora wrote:
>
> > Hey all,
> > I've done quite a bit of searching and reading and am having some
> trouble
> > getting started integrating VTK into my application.  I'm a new user,
> but
> > I've spent enough time looking that I don't think I'm missing anything
> too
> > obvious.
> >
> > I have a fairly simple visualization application written with OpenGL.  I
> > want to visualize some more complicated data sets, so I wanted to write
> a
> > version that works with VTK.
> >
> > My visualization application is fed in data from a motion capture
> system, so
> > right now, every time my application loop updates, it reads the data
> from
> > the mo-cap system, and updates the rendering with very specific calls to
> > glFrustum and gluLookAt.  The front face of the frustum volume is almost
> > never centered around the z axis, so I can't simulate the frustum
> creation
> > by simply providing a vtkCamera with a position, direction, and viewing
> > angle.  I need more control of the frustum shape than that functionality
> > seems to provide.
> >
> > Can anyone advise me on how to create a simple vtk application with no
> user
> > control where the frustum and camera position are automatically updated
> by
> > the program every cycle of the main program loop?  From what I can tell,
> I
> > don't want to use an interactor since the user will not be interacting
> with
> > the application (the user interacts with the motion capture system, and
> the
> > application simply queries data from the motion capture system when it
> is
> > rendering).  Again, I need to be able to create frustums that aren't
> > centered around the z axis.
> >
> > Thanks in advance!
> >
> > -Mark Waligora
> >
>
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