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WTF?! Will compile with llLookAt but not llRotLookAt?!
CharlieFinlayson Humbridge
Registered User
Join date: 17 Nov 2009
Posts: 3
11-22-2009 14:56
//Causes Object to look at nearest Avatar.
default
{
state_entry()
{
llSensorRepeat("", "", AGENT, 20.0, PI, 0.2);
}

sensor(integer total_number)
{
llRotLookAt(llDetectedPos(0) + <0.0, 0.0, 1.0>, 3.0, 1.0);
}
}

This just won't compile, but it will when llRotLookAt is changed to llLookAt. Why!?

"Function call mismatches type or number of arguements" is the message I get.
Dora Gustafson
Registered User
Join date: 13 Mar 2007
Posts: 779
11-22-2009 15:10
1. argument for the llRotLookAt is a rotation
1. argument for the llLookAt is a vector

llRotLookAt won't compile if the 1. argument is a vector

Please note: llLookAt will point the UP(Z-vector) at the point and llRotLookAt will point the FWD(X-vector) in the given direction.
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CharlieFinlayson Humbridge
Registered User
Join date: 17 Nov 2009
Posts: 3
11-22-2009 15:39
I know that, and I figured out it was a rotation instead of a vector.

So I tried the llLookAt, and changed the offset to higher, but it still behaves really mysteriously, doesn't seem to look the at my avatar the way it should. I tried llRotLookAt, using what I think was a correct llEuler2Rot conversion, and it just rotated totally randomly depending on where I was standing. I just want my virtual pet to look at me on the X or Y axis while being stuck to the ground. Why is that so hard? :(
SuezanneC Baskerville
Forums Rock!
Join date: 22 Dec 2003
Posts: 14,229
11-22-2009 16:16
Since it seems you changed your code from the initial post, why not post the revised code that compiles but doesn't work?
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Innula Zenovka
Registered User
Join date: 20 Jun 2007
Posts: 1,825
11-22-2009 17:07
Someone in this thread had a similar problem -- might be of interest /54/5b/350751/1.html
Kayaker Magic
low carbonated footprint
Join date: 11 Sep 2008
Posts: 109
11-22-2009 17:17
Heres a version that works (yes, I tested it!)
//Causes Object to look at nearest Avatar.
default
{
state_entry()
{
llSensorRepeat("", "", AGENT, 20.0, PI, 1);
}

sensor(integer total_number)
{
vector fwd=llVecNorm(llDetectedPos(0)+<0,0,1>-llGetPos()); //vector pointing above avatar
vector lft=<0,0,1>%fwd; //cross product is in the XY plane
rotation rot=llAxes2Rot(fwd,lft,fwd%lft); //convert to rotation
llRotLookAt(rot, 3.0, 1.0);
}
}
The problem is you need a rotation, but what you have is only a location. The vector from the prim to the avatar (plus 1 meter to kind of point at the head) can be converted to a rotation. Here I chose a LFT vector that is perpendicular to the direction vector, and parallel to the XY plane (perpendicular to <0,0,1>. That keeps the prim oriented right side up with no side-to side tilting. Now there is enough information for llAxes2Rot to rotate the prim.
Keeping it on the ground is a different problem, this rotation trick will work from above the ground. (But not DIRECTLY above where the cross product will fail!)