Same scene to multiple viewports?

Similar Threads:

1.Multiple Viewports

I'm working on a program used for pretty detailed model visualization. 
Recently emerged the need for multiple views, each with a different 
angle of the model. I'm using multiple viewports in a single window and 
I'm not sure that I'm doing it right. I've got 6 viewports, all showing 
the same model. When drawing, I go through every viewport and render the 
  same model over and over in each viewport respectively. This, of 
course, slows the frame rate 6 times. Now, this just doesn't seem right, 
having to feed the opengl with model coordinates just to have a 
different viewing angle. Is this the right way to do it?
I don't think this is important, but model is made of approx. 150000 
polygons, so around million polygons shouldn't be a problem. I've got a 
pretty good graphics card, but it's still jerky.

Any help is appreciated,
thanks,
Killroy

2.multiple viewport problem with bitmap

Hi everyone,

I am trying to use OpenGl with C++ and am having problems with multiple
viewports. The problem happens when I try to display bitmaps in twp
different viewports.

I tried various combinations. The code seems to behave when I am
drawing triangles etc. However, when I try doing something with
bitmaps, it fails.

Here is the code in a nutshell:

glMatrixMode(GL_MODELVIEW);
glViewport(m_xPos, m_yPos, m_width,m_height);
glLoadIdentity();
glDrawPixels(bmp.bmWidth, bmp.bmHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE,
bmp.bmBits);

// same code, but different set of values for the position...
glMatrixMode(GL_MODELVIEW);
glViewport(m_xPos, m_yPos, m_width,m_height);
glLoadIdentity();
glDrawPixels(bmp.bmWidth, bmp.bmHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE,
bmp.bmBits);

SwapBuffers(hDC);

Now, the two bitmaps seem to get drawn on the same viewport... I would
appreciate any help anyone can give me regarding this...

Cheers,
xargy

3.multiple viewports .... same texture

Hello,
I'm trying to optimize my current program, which consists of 5 viewports 
displaying the same object from different angles. The problem I have is 
that I'm loading a texture which is quite large, too large to be loaded 5 
times. At the moment I have 5 QGLWidgets under QT, each one with its own 
initGL and paintGL methods and each one loading its own copy of the same 
texture and displaying it in a different way.

In a first attempt to optimize the display, I've tried using the  
glBindTexture(GL_TEXTURE_3D_EXT,1) command before the glTexImage3DEXT(....) 
command in each widget and again before painting the texture in each 
widget. So, theoretically, the texture should get loaded once to a texture 
object, then get written over 4 times by the subsequent initGL calls, and 
then it should get used by the paintGL's each time.

The problem is it doesn't seem to work. It still loads the textures 5 
times. I know this, because for one, there is a sharp performance decrease 
when the textures don't all fit in the memory (one copy does, 5 don't). 
Secondly, in the initGL I added something like this before/after the 
texture loading command. The subsequent viewport display a white texture, 
i.e. they're not using the one that was loaded:

if (first time called in program){
    glBindTexture(GL_TEXTURE_3D_EXT,1);    
glTexParameteri(GL_TEXTURE_3D_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexImage3DEXT(GL_TEXTURE_3D_EXT, 0, GL_LUMINANCE_ALPHA,
		    sizex,sizez,sizey,
		    0,
		    GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, data);
}

Maybe the qtwidget does something so that the openGL contexts don't affect 
each other, so the glBind has no effect....

Also, does anybody know of a way to check how much texture memory is 
available?

Thanks for the ideas

4.Multiple overlapping viewports

How can I make two viewports, one of them covering all the window
client area and another one covering a small recrangle near a corner?

Thanks in advance.

5.Multiple scenes & cameras

Hi,

I am using two cameras to render two (sub-)scenes on the same screen. 
This way, I can independantly select the orientation/position of the 
camera for each subscene. Everything is perfect ... except that I'd
like the second subscene to be always rendered on the top of the 
first.

Any hint ?

Regards,

S.B.

6. Drawing to one scene with multiple classes.

7. Simple question about multiple lights on a scene

8. Multiple Scene Render