llRot2Up
vector llRot2Up(rotation Rotation)Returns the up vector defined by Rotation.
Returns the up axis represented by the Rotation.
Parameters
Rotation(rotation)
Computes the orientation of the local z-axis (up-direction of prim) relative to the parent (the root prim or the world).
Mathematical Equivalent
Section titled “Mathematical Equivalent”Mathematically equivalent to:
ret = llVecNorm(<0., 0., 1.> * q);If q is known to be a unit quaternion then it can be simplified as:
ret = <0., 0., 1.> * q;Keep in mind that object and agent rotations will always be unit quaternions. For example, <0.0, 0.0, 1.0>*llGetRot() is about 25-30% faster than llRot2Up(llGetRot()) depending on the VM used. If done often and at extremely fast rates, it can be advantageous to even save <0.0, 0.0, 1.0> to a local/global variable and reuse it.
Examples
Section titled “Examples”Move a prim 5 metres forwards along its own z axis, when touched, no matter how the object is oriented in world. This works for a root or child prim:
default{ touch_start(integer total_number) { vector v = llRot2Up( llGetLocalRot() ); llSetPos( llGetLocalPos() + v * 5 ); }}Can be useful to identify the orientation of the local horizontal-plane of the prim, since its z-axis is always perpendicular to this local horizontal plane.