Multiple viewport problem - c++

Question

I'm setting up so I can switch between either one or four viewports but I got some trouble.
In my bottom right viewport I got camera view, the same camera that I can switch to full view on. The other three viewports are working with fixed locations but the bottom right viewport is compressed on the y scale and half of the picture on the x scale is missing.
void display(int what)
{
if(what==5){glViewport(0, 0, w, h);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
ca.lookAt();}
if(what==1){glViewport(0, 0, w/2, h/2);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(75,15,-5,0,5,-5,0,1,0);}
if(what==2){glViewport(w/2, h/2, w, h);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0,110,0,20,0,20,1,0,0);}
if(what==3){glViewport(w/2, 0, w, h/2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, float(320) / float(240), 0.1f, 100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
ca.lookAt();}
if(what==4){glViewport(0, h/2, w/2, h);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(185,75,25,0,28,0,0,1,0);}
//glMatrixMode(GL_MODELVIEW);
//glLoadIdentity();
////gluLookAt(cos(shared.time) * shared.distance, 10, sin(shared.time) * shared.distance, 0, 0, 0, 0, 1, 0); // Roterar kameran kring origo genom att skapa en ny vymatris varje bildruta
////ca.orbitYaw(0.05);
//ca.lookAt();
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
drawScene();
drawCamera();
glutSwapBuffers();
}
void viewport(){
glEnable(GL_SCISSOR_TEST);
if(!divided_view_port)
{
glViewport(0, 0, w, h);
glScissor(0,0,640,480);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 100.0f);
display(5);
}
else
{
////////////////////// bottom left - working
glViewport(0, 0, w/2, h/2);
glScissor(0,0,w/2,h/2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(1);
//////////////////////
////////////////////// top right - working
glViewport(w/2, h/2, w, h);
glScissor(w/2,h/2,w,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(2);
//////////////////////
////////////////////// bottom right -working
glViewport(w/2, 0, w, h/2);
glScissor(w/2,0,w,h/2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(3);
////////////////////////
////////////////////////// top left
glViewport(0, h/2, w/2, h);
glScissor(0,h/2,w/2,h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, w / h, 0.1f, 300.0f);
display(4);
///////////////////////////
}
glDisable(GL_SCISSOR_TEST);
glMatrixMode(GL_MODELVIEW);
}

Answer 1

glViewport() takes an offset and a size.
Your code seems to be passing lower-left and upper-right coordinates.
Try these:
glViewport( 0, 0, w/2, h/2); // lower-left
glViewport(w/2, 0, w/2, h/2); // lower-right
glViewport(w/2, h/2, w/2, h/2); // upper-right
glViewport( 0, h/2, w/2, h/2); // upper-left