3.7.3 Surf3A sample

Function surf3a is similar to surf3 but its transparency is determined by another data. The sample code is:

int sample(mglGraph *gr)
{
  mglData c,d;  mgls_prepare3d(&c,&d);
  gr->Title("Surf3A plot"); gr->Rotate(50,60);
  gr->Light(true);  gr->Alpha(true);
  gr->Box();  gr->Surf3A(c,d);
  return 0;
}