Rez an object on the ground so it faces towards the Owner?

[jak Scribe]

Hi again,

How can I script an object so that it turns and faces me apon being rezzed on the ground?

 

I did try searching here but it turned up thousands of hits

 

Edited October 26, 2023 by jak Scribe

[Rolig Loon]

So, ...

Step 1:  You rez the object, setting it to ZERO_ROTATION on rez  (using llRezAtRoot, that's the rotation parameter)

Step 2: On Rez, you quickly locate the object's owner. One fast way to do that is to ask 

          vector OwnerPos = llList2Vector(llGetObjectDetails( llGetOwner(),[OBJECT_POS]), 0);

Step 3:  Adjust the Z value of OwnerPos to be the same as the Z value of llGetPos() (that is, the object's own position on rez).  This will make the object keep its Z-axis vertical as it rotates.

Step 4: Rotate the rezzed object to face the owner with llSetLinkPrimitiveParamsFast(LINK_THIS, [PRIM_ROTATION,llRotBetween( llGetPos(), CorrectedOwnerPos)]);

[Quistess Alpha]

1 hour ago, Rolig Loon said:

llRotBetween( llGetPos(), CorrectedOwnerPos)

That may work (I've not tried it) but I think you meant llRotBetween(<1,0,0>, CorrectedOwnerPos-llGetPos()); you want to rotate by an angle defined by a line sticking out from the object going in the forward (x?) direction (<1,0,0>), and a line sticking out from the object pointing at the owner (ownerPos-llGetPos()) rather than 2 lines pointing from the region origin to the owner & object.

to look up/down at the owner, I think you could right multiply that by llRotBetween(CorrectedOwnerPos-llGetPos(),OldOwnerPos-llGetPos());

[Rolig Loon]

You're probably right. That's the problem with posing a response off the cuff too close to bedtime, without taking the time to go in world to see if physics agrees with your brain. Your solution does look more plausible.  Still, the magic is in llRotBetween. That's where the OP has to do his own experiments.

[Quistess Alpha]

14 minutes ago, Rolig Loon said:

the magic is in llRotBetween

actually for a better conceptual understanding, I'd recommend going through the trig with llAtan2()  and constructing an orientation with a product of llAxisAngle2Rot(). llRotBetween often doesn't do what you think it does when used outside of simplified contexts.

[Xiija]

@jak Scribe

mostly the above + the stuff on the wiki & llRotLookAt ...

default
{
    on_rez(integer start_param)
    {  llResetScript();       
    }
    state_entry()
    {  vector pos      = llGetPos();
       vector OwnerPos = llList2Vector(llGetObjectDetails( llGetOwner(),[OBJECT_POS]), 0);     
       llRotLookAt( llRotBetween( <1.0, 0.0, 0.0>, llVecNorm( <OwnerPos.x, OwnerPos.y, pos.z> - pos ) ), 1.0, 0.4 );
    }    
}

 

Edited October 26, 2023 by Xiija

[jak Scribe]

Thanks Guys

I just now have one problem...my Object ends up on its side and the other way around LOL

In what directions must the root prim of my Object be created to end up facing as wished?

[Frionil Fang]

If you're using the llRotBetween method, you might want to change the start axis it uses, i.e. the first vector: llRotBetween(<0, 1, 0>, end) or llRotBetween(<0, 0, 1>, end). Depends on the object and how it's built which way is the "visual front side", the x-axis i.e. <1, 0, 0> being towards the front is just a convention that isn't necessarily followed.

<0, 1, 0> points to the left of the object's local perspective, <0, 0, 1> points up. You can also use -1s to point backward, right or down.

[Rolig Loon]

To save yourself a LOT of trouble, always build with the root prim's +Z axis pointing UP and its +X axis facing FORWARD.  When you set the object to ZERO_ROTATION, it will be standing up and facing East.

[jak Scribe]

I changed my whole object so the root prim is as you suggested Rolig.

I then had to changed the llRotBetween(<1.0, 0.0, 0.0), to <0.0, 1.0, 0.0) as Frionil suggested and now it sits correctly when I rez it.

 

Thanks again guys