Link Numbers
Each prim that makes up an object has an address, a link number. To access a specific prim in the object, the prim's link number must be known. In addition to prims having link numbers, avatars seated upon the object do as well.
- If an object consists of only one prim, and there are no avatars seated upon it, the (root) prim's link number is zero.
- However, if the object is made up of multiple prims or there is an avatar seated upon the object, the root prim's link number is one.
When an avatar sits on an object, it is added to the end of the link set and will have the largest link number. In addition to this, while an avatar is seated upon an object, the object is unable to link or unlink prims without unseating all avatars first.
Counting Prims & Avatars
There are two functions of interest when trying to find the number of prims and avatars on an object.
integer GetPrimCount() { //always returns only the number of prims
if(llGetAttached())//Is it attached?
return llGetNumberOfPrims();//returns avatars and prims but attachments can't be sat on.
return llGetObjectPrimCount(llGetKey());//returns only prims but won't work on attachments.
}
See
llGetNumberOfPrims for more about counting prims and avatars.
Errata
If a script located in a child prim erroneously attempts to access link 0, it will get or set the property of the linkset's root prim. This bug (BUG-5049) is preserved for broken legacy scripts.
The position of an avatar on a sit target can be determined with the use of llGetObjectDetails (see llSitTarget for an example).
If an object has multiple seats (each seat has a script that sets a sit target with llSitTarget, or the linkset has a script that assigns several llLinkSitTargets), the following method determines which sit target an avatar ends up at:
- If the prim that is clicked on has a sit target and that sit target is not full, that sit target is used.
- If the prim that is clicked on has no sit target, and one or more other linked prims have sit targets that are not full, the sit target of the prim with the lowest link number will be used.