### Sectors and portals

Sectors and portals are a very important tool to speed up the rendering of levels. Well defined sectors can greatly speed up rendering and allow various tricks, to understand what they are, read this guide.
The exporter supports 2 different ways of creating your levels:

1) One sector per Max scene

2) Multiple sectors per Max scene

#### One sector per Max scene

Be sure you have no objects named "_sect_" in the scene.

The sector name will be taken from the "roomname" custom property that you added on the Max scene.

All objects present in the scene will be exported as part of the sector.

#### Multiple sectors per Max scene

Create a "Dummy" object (Create->Helpers->Dummy) for each sector you want to have in the scene, and name it:
"_sect_sectorname"
where "sectorname" is the name of your sector. The sector will be exported with name=sectorname

To add objects to one specific sector, use the "Select and Link" button in the toolbar making the objects children of the Dummy sector object (click on the object then drag to the Dummy sector object. You can also do that with multiple objects selected).

Remember that:
- the camera object must be parented to the right sector
- a portal that brings from sector1 to sector2 must be linked to sector1
- all objects that are not linked to a _sect_ object will not be exported

TODO!!!! SECTOR_TYPE=simple

#### Adding Portals

To add a portal to a 3dsmax scene follow this guidelines:

- the object name must start with "_p_" . For example "_p_laanx1" is a valid portal name.
- it MUST be a mesh with 2 planar triangle polygons (a square similar to a door is perfect).
- add a property to the object (see 'Objects' chapter for details on how to add a property) called "PORTAL" that points to the roomname of the sector where that portal will lead to.
  Example: PORTAL=plaza

When you have a portal that arrives in the middle of a sector. i.e. the player will have geometry behind him when arriving in the new sector, then you have to use a property to tell the engine that it should consider differently that geometry while looking through the portal. The flag is: ARRIVESINTHEMIDDLE. This flag is quite bad for performances, so should be avoided as much as possible. Default is no.

- ARRIVESINTHEMIDDLE=yes

When you have a portal that is placed in the middle of a sector i.e. there is geometry behind the portal in the sector it's placed, then you have to use a property to tell the engine that it should consider differently that geometry while looking through the portal. The flag is: STARTSINTHEMIDDLE. This flag is not that bad for performances. Default is no.

- STARTSINTHEMIDDLE=yes

When testing a level remember that the target sector must be loaded in memory to have the portal "active". If you don't load the other sector (or level), the portal will just look black or with checkerboard texture and will be solid, like a wall.

#### Adding a Warping Portal

As you know, a portal is not bi-directional, so by itself it defines a starting point and a destination point. The destination point is by default in the same coordinates as the portal is, but located in the destination sector. Let's say we have a portal placed in coords (1,10,20) located in sector "one" with destination sector "two". This portal will be seen in sector one at coords (1,10,20) and when the player will pass through it, it will bring in sector "two" at coords (1,10,20).

This means that if you have many linked sectors, you will end up modeling things at coords 2000 or 10000, having to figure out the position to place your new sector based on the location of the incoming portals.

A "warping" portal gives you the ability to define which is the exact destination point, the place where the player will appear when passing through the portal. Obviously the same rule is applied when the player looks at the portal, so he will see the geometry present at the specified target position.

To easily specify a target position, instead of inserting manually the coordinates, you can just place a dummy object in the scene to represent the target position. If the target will be another portal, I strongly recommend to merge that second portal into your scene, to rename it _n_something (so it's not exported), and use this object as the warp destination target.

To have a warping portal, add the usual PORTAL property, plus a WARPTARGET property:

PORTAL=two
WARPTARGET=_n_mylocation

the WARPTARGET property tells the exporter to check the object '_n_mylocation' and extract his coords. It subtracts the portal coords from the target object coords, and displace the portal of that amount.

Let's say that our portal (_p_portal1) is in coords: x=3, y=0 and that the target object (_n_mylocation) is in coords x=5, y=0. When exporting the distance from one to the other is calculated: x=2. The portal _p_portal1 will be then exported with a warp of x=2. This means that the sector "two" (destination sector) will be displaced of x=2 when viewed from _p_portal1.

Next: Occluders