OCCL is a section in the item placement file in Vice City, San Andreas, and GTA IV. It is used to create occlusion culling zones that helps make the game run smoother in certain parts of the world. Since it is wasteful to render models behind opaque models, these zones can disable the rendering of any models that are directly behind the zones.


San Andreas The section is used in , , , and files. occluint.iploccluLA.iplocclusf.iploccluveg.ipl

MidX, MidY, BottomZ, WidthX, WidthY, Height, Rotation, , ,
Simbol Identifier Type Description
A,B MidX, MidY float[2] The X and Y coordinates of the center of the occlusion zone.
C BottomZ float The bottom Z coordinate of the occlusion zone.
D,E WidthX, WidthY float[2] The width of the occlusion zone in units.
F Height float The height of the zone — the difference between the top and the bottom of the zone.
G Rotation float The rotation of the occlusion zone in degrees.
H,I float
J int


When removing buildings from the world, you may see unexpected pop ups caused by existing occlusion zones. Deleting all the occlusion zones is the easiest solution. An example of this issue is the Liberty City project. Before this section was researched, the team experienced unexpected pop ups with models loading and unloading behind areas where Vice City's buildings used to be. Someone realized that the was the problem and deleted every line in that file. The pop ups disappeared and the issue was resolved. occlu.ipl


Total number of OCCL entries in: Vice City: 344 (max 350)