Re: OpenGL postdraw using Performer coordinates?

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Nicolas Gauvin (nicolas++at++cae.ca)
Tue, 6 Jan 1998 17:58:00 -0500

On Jan 6, 8:56am, Jan Barglowski wrote:
> Subject: OpenGL postdraw using Performer coordinates?
> Performers:
>
> I'd like to draw an OpenGL line between two locations in my Performer
> scene. How do I convert the Performer coordinate system to OpenGL?
>

In a pfChannel draw callback you just need to draw your line with
its 3D world coordinates. The GL modelview and projection matrices are
already setup correctly at that point:

void
drawCB(pfChannel *chan)
{
  chan->clear();
  pfDraw();

  pfPushState();
  pfBasicState();
  glColor...
  glBegin(GL_LINES)
  glVertex...
  glVertex...
  glEnd();
  pfPopState();
}

Its only in the 2D case that you have to reset the matrices. But then its
simpler to use a second overlapping ortho pfChannel that doesn't clear.

-- 
Nicolas Gauvin              CAE Electronics Ltd., 8585 Cote De Liesse
3D Graphics Software        Saint-Laurent, Quebec, Canada, H4L-4X4
nicolas++at++cae.ca              Tel: (514) 341-2000 x2275, Fax: (514) 340-5496 
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