Question

For the following code segement, my problem is that the two objects are intersected, but the views (lower figure) are not correct, object 1 (box) is inserted into the cylinder but the sideview (lower figure) is not correct, it looks like the yellow box is behind the cylinder. How can I make it look they are intersected?

    glColor3f(1,1,0);
    drawobj1(); // draw box 
    glColor3f(1,0.5,0);
    drawobj2();draw Cyclinder() using gluCylinder

Answer 1

It is behind the cylinder. It is both inside and behind it. Part of the box is inside it, and part of it is behind it.

Imagine a fork embedded in the side of a can. You can rotate the can so that it appears like the cylinder in your diagram. The fork is still embedded in it, but from that angle, you can only suspect that it is based on what you know about the length of a fork.

Your problem is the lack of visual depth cues, brought on by the fact that this scene lacks lighting, textures, and everything else that your brain normally would use to actually interpret something.