One can easily create stereo image in MathGL. Stereo image can be produced by making two subplots with slightly different rotation angles. The corresponding code looks like this:
int sample(mglGraph *gr)
{
mglData a; mgls_prepare2d(&a);
gr->Light(true);
gr->SubPlot(2,1,0); gr->Rotate(50,60+1);
gr->Box(); gr->Surf(a);
gr->SubPlot(2,1,1); gr->Rotate(50,60-1);
gr->Box(); gr->Surf(a);
return 0;
}