scene_gap(3)                    Allegro manual                    scene_gap(3)



NAME
       scene_gap - Number controlling the scene z-sorting algorithm behaviour.
       Allegro game programming library.

SYNOPSIS
       #include <allegro.h>


       extern float scene_gap;

DESCRIPTION
       This number (default value = 100.0) controls the behaviour of the z-
       sorting algorithm. When an edge is very close to another's polygon
       plane, there is an interval of uncertainty in which you cannot tell
       which object is visible (which z is smaller). This is due to cumulative
       numerical errors for edges that have undergone a lot of transformations
       and interpolations.

       The default value means that if the 1/z values (in projected space)
       differ by only 1/100 (one percent), they are considered to be equal and
       the x-slopes of the planes are used to find out which plane is getting
       closer when we move to the right.

       Larger values means narrower margins, and increasing the chance of
       missing true adjacent edges/planes. Smaller values means larger
       margins, and increasing the chance of mistaking close polygons for
       adjacent ones.  The value of 100 is close to the optimum. However, the
       optimum shifts slightly with resolution, and may be application-
       dependent. It is here for you to fine-tune.




SEE ALSO
       create_scene(3), clear_scene(3), destroy_scene(3), render_scene(3),
       scene_polygon3d(3)



Allegro                          version 4.2.3                    scene_gap(3)
