osx man page for scene_gap

scene_gap(3alleg4)						  Allegro manual						scene_gap(3alleg4)

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(3alleg4), clear_scene(3alleg4), destroy_scene(3alleg4), render_scene(3alleg4), scene_polygon3d(3alleg4)

Allegro 							   version 4.4.2						scene_gap(3alleg4)