d3d_set_culling(enable)
| Argument | Description |
|---|---|
| enable | Switches on (true) or off (false) back-face culling |
Returns: N/A
A 3D triangle has a front and a back side. The front side
is said to be the side where the vertices are defined in
counter-clockwise order. Now, normally both sides are drawn,
but if you make a closed shape then this is a waste of processing
power because the back side of the triangle can never be seen. It's
in these cases that you can switch on backface culling. This saves
about half the amount of drawing time but it means you have the
task of defining your polygons in the correct way to prevent
issues.
d3d_set_culling(true);
d3d_primitive_begin(pr_trianglelist);
d3d_vertex(100, 100, 0);
d3d_vertex(100, 200, 0);
d3d_vertex(150, 150, 200);
d3d_vertex(100, 200, 0);
d3d_vertex(200, 200, 0);
d3d_vertex(150, 150, 200);
d3d_vertex(200, 200, 0);
d3d_vertex(100, 100, 0);
d3d_vertex(150, 150, 200);
d3d_vertex(100, 100, 0);
d3d_vertex(100, 200, 0);
d3d_vertex(200, 200, 0);
d3d_primitive_end();
The above code will draw a pyramid with the back faces (interior faces) being culled (not drawn).