About capture graph in glut or opengl

Hi there, i’m a newb here, i got a sample code and i’ve already load my .obj model in the program.

But now what i want to do is to capture the graph from the glut-screen that showing my 3d model, can anyone help me :)? thanks alot.

here’s the sample code link

3D obj model loader

You can use glreadPixels to get back all the pixels on screen at once, onto an array.