scene_gap(3) Allegro manual scene_gap(3)NAMEscene_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 mar‐
gins, and increasing the chance of mistaking close polygons for adja‐
cent ones. The value of 100 is close to the optimum. However, the
optimum shifts slightly with resolution, and may be application-depen‐
dent. It is here for you to fine-tune.
SEE ALSOcreate_scene(3), clear_scene(3), destroy_scene(3), render_scene(3),
scene_polygon3d(3)Allegro version 4.4.2 scene_gap(3)
