From: Dick Rous (dick++at++sgi.com)
Date: 12/10/2003 00:12:11
You need to set up the proper projection and modelview matrix.
To safely save/restore Performer and OpenGL state, specify the
following in a DRAW callback:
pfPushState(); // Push Performer state.
pfBasicState(); // Set default state.
glMatrixMode(GL_PROJECTION); // Push projection matrix, set
identity.
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, 1280.0, 0.0, 1024.0, -100.0, 100.0);
glMatrixMode(GL_MODELVIEW); // Push modelview matrix, set identity.
glPushMatrix();
glLoadIdentity();
glRasterPos3f(0.0f, 1024.0f, 0.0f); // Draw image.
glDrawPixels(xSize,
ySize,
GL_RGBA,
GL_UNSIGNED_BYTE,
image);
glMatrixMode(GL_PROJECTION); // Restore OpenGL matrices.
glPopMatrix();
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
pfPopState(); // Restore Performer state.
Hope this helps,
Dick.
> -----Original Message-----
> From: faculaganymede [mailto:faculaganymede++at++yahoo.com]
> Sent: Wednesday, 10 December, 2003 02:42
> To: SGI Performer MailList
> Subject: [info-performer] glRasterPos2i()
>
>
> Hi all,
>
> I have a glRasterPos2i() question.
>
> In my channel draw callback function, I am doing a
> glReadPixels() and glDrawPixels(). I tried
> positioning the current raster position before
> glDrawPixels() using glRasterPos2i(x, y). But,
> whenever I set x and y to a value other than 0, the
> current raster position starts to move relative to the
> eye point at run-time, i.e. the pixel area drawn by
> glDrawPixles are moving, even though x and y are
> constant. Does anyone know why this happens?
>
>
> =====
> Thanks,
> faculaganymede
>
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