The JOINT system has been removed and is not available anymore.
Joint
A joint is a way to
link ("join") moving
physical prims together in
SL.
Andrew Linden once wrote (source?; slightly edited to match the current state of SL):
All About Joints
Here is a quick rundown of joints.
To fully understand this quick tutorial you should already know all about linking. That is, you should know what the "
root primitive" of a
linked set is.
Making Joints
Each joint connects two
objects. For this discussion I will call one of them the
arm and the other the
pivot.
To make a joint, select one of the objects, then hold down the shift key and select the second object. Go to the menu "Tools -> Make Joint" and select the type of joint you want.
The first object you selected will be the
arm and the second object you selected will be the
pivot.
For best results, disable "
physics" for the two pieces before the joint is created. Then enable "physics" on the appropriate pieces.
Note that until one of the pieces has "physics" enabled, selecting one will not necessarily select the entire jointed object. However, when one of the pieces has "physics" enabled then selecting one should automatically select the other piece.
Hinge
If you enable "physics" just for the
arm, then the
arm will rotate about the
pivot's local Z-
axis (i.e. the blue one) that passes through the
center-of-mass of the
pivot's root primitive.
If you enable "physics" just for the
pivot, then the
pivot will rotate about its own
local Z-axis that passes through its center-of-mass.
This is how you make a "wheel-like" joint: secure the
arm and use a cylindrical
pivot that is free to rotate. Don't even bother trying to make a car using 4 wheels. Joints are not stable enough to make
vehicles yet, but you can make doors, propellers (maybe), and some other stuff that doesn't suffer too many complicated
collisions.
If you enable "physics" for both, well... you get both.
Point-to-Point
If you enable "physics" for just the
arm then the
arm will swing freely from the center of mass of the
pivot's root primitive. The
arm will also be able to spin about the axis that connects it to the
pivot.
If you enable "physics" for just the
pivot then... uh... oops, that's
bugged. The point of swing is not right... I'll have to fix it.
The wind-chimes were made using point-to-point hinges.
Limited Point-to-Point
Don't use limited point-to-point joints for things you want to last for very long. The limited point-to-point joint has some problems surviving the save-load cycle which we haven't had time to fix yet. However, making a fresh one should work.
Basically, it is the same as the point-to-point except the center of the joint is the midpoint between the two centers of
mass, and the amount of swing to the side is limited. Think of it like your shoulder (except with spin)... you can't swing your
arm to arbitrary orientations behind you.
Andrew Linden explains the joint removal process in this
forum post.
Physics |
Physical |
Link