How can I judge if there is a avatar sit on a part of a prim?

[brightacs]

HI!Guys! Do you know how to judge if there is a avatar sit on a part of a prim using LSL?

[Innula Zenovka]

If the object has a sit target set with llSitTarget or llLinkSitTarget, you can test for llAvatarOnSitTarget or llAvatarOnLinkSitTarget.   Those will return the uuid of the avatar, or NULL_KEY if no one is sitting.

Alternatively, you can test for if (llGetNumberOfPrims()>llGetObjectPrimCount(llGetKey())).   If it is, that means someone is seated on the object -- llGetObjectPrimCount returns the number of prims, and ignores seated avatars, while llGetNumberOfPrims counts both prims and avatars.