Create a hidden line drawing of a collection of objects.

Input parameters:

1. Sh → Shapes to draw.
2. Vw → View of objects.
3. Pl → Clipping planes to include in the drawing.
4. Pg → Page for hidden line drawing.

Output parameters:

1. Cr → Visible curves in the drawing.
2. Cc → Clipped curves in the drawing.
3. Cx → Hidden curves in the drawing.
4. Cs → Silhouette curves of the entire scene.
5. Pt → Visible points in the drawing.
6. Px → Hidden points in the drawing.