lighting problem

Hi all

please help me!

  1. how can I set the light source to be always positioned at a specific place in window. I don’t want to rotate or translate light source with the object.

  2. When we have drawn an triangle as follows,
    glBegin(GL_TRIANGLES);
    glVertex3f(p3d1->x,p3d1->y,p3d1->z);
    glVertex3f(p3d3->x,p3d3->y,p3d3->z);
    glVertex3f(p3d2->x,p3d2->y,p3d2->z);
    glEnd();
    how can we get the light effect in both front and back side?

1/ check the faq (link first page)
2/ enable 2 sided lighting