POV-Ray : Newsgroups : povray.off-topic : Trying to code an "offset rotation" for SL. Server Time
6 Nov 2024 06:24:32 EST (-0500)
  Trying to code an "offset rotation" for SL. (Message 1 to 10 of 11)  
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From: Patrick Elliott
Subject: Trying to code an "offset rotation" for SL.
Date: 14 Jul 2008 23:55:29
Message: <MPG.22e5cd9fb9b0842b98a180@news.povray.org>
Here is what I have:

vector Rot = <0,0,0>;

default
{
    state_entry()
    {
        llSetTimerEvent(0);
    }

    touch_start(integer total_number)
    {
        llSetTimerEvent(0.1);
    }
    
    timer()
    {
        vector pos = llGetLocalPos();
        vector npos;
        float x = pos.x;
        float y = pos.y;
        float z = pos.z;
        Rot = Rot + <0.5,1,1>;
        if (Rot.x > 359)
        {
            Rot.x = 0;
        }
        if (Rot.y > 359)
        {
            Rot.y = 0;
        }
        if (Rot.z > 359)
        {
            Rot.z = 0;
        }
        
        y = llCos(Rot.x)*y - llSin(Rot.x)*z;
        z = llSin(Rot.x)*y + llCos(Rot.x)*z;
        
        z = llCos(Rot.y)*z - llSin(Rot.y)*x;
        x = llSin(Rot.y)*z + llCos(Rot.y)*x;
        
        x = llCos(Rot.z)*x - llSin(Rot.z)*y;
        y = llSin(Rot.z)*x + llCos(Rot.z)*y;
        npos = <x,y,z>;
        
        llSetPos(npos);
        llSetLocalRot(llEuler2Rot(Rot * DEG_TO_RAD));
    }
}

The problem is, when it runs it "starts" where I placed the object, then 
the distance from it to the main object shrinks each time. I.e., if the 
main object is at <0,0,0> and the "child" is at <0.00809, 0.00888, 
1.29409>, then the following passes do this:


[20:43]  Object: <-0.25235, -0.23316, 0.69239>
[20:43]  Object: <-0.01824, 0.22825, -0.05867>
[20:44]  Object: <0.15534, -0.26676, 0.06066>
[20:44]  Object: <-0.30133, 0.21328, 0.07791>
[20:44]  Object: <0.22322, 0.14242, -0.26685>
[20:44]  Object: <0.10885, 0.17888, -0.19385>
[20:44]  Object: <-0.16811, -0.19235, -0.21766>
[20:44]  Object: <-0.12149, 0.12519, 0.19799>
[20:44]  Object: <0.02029, -0.11608, -0.13033>
[20:44]  Object: <-0.11644, 0.11593, 0.12039>
[20:44]  Object: <0.15958, 0.01220, -0.11591>
[20:44]  Object: <0.12300, 0.06275, -0.01218>
[20:44]  Object: <-0.05051, -0.04145, -0.06274>
[20:44]  Object: <0.00101, 0.03214, 0.04145>
[20:44]  Object: <0.03001, -0.03942, -0.03215>
[20:44]  Object: <-0.02687, 0.03668, 0.03942>

Getting closer and closer to <0,0,0>.

So, what am I doing wrong here, or what equations do I need instead. The 
site I looked at "implied" that the existing "location", i.e., X,Y,Z of 
the object would feed through the calculations to end up with something 
the same "distance" from the center point as before. However, it was 
also code intended to be used in Java or Flash for 3D, so the example 
was a mess of crap that involved translating that into 2D points. 
Obviosly I am missing something here, but I have no clue why/how the 
code is supposed to work, so have no clue why it simply doesn't in this 
case. (llGetLocalPos returns the position relative to the location of 
the "master" prim, i.e., if the master is at 143,12,23, then the 
"local" point is still centered on 0,0,0, supposedly, so that's not 
where the issue seems to be coming from. :( )

Help please!! 

-- 
void main () {

    if version = "Vista" {
      call slow_by_half();
      call DRM_everything();
    }
    call functional_code();
  }
  else
    call crash_windows();
}

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From: scott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 15 Jul 2008 03:01:34
Message: <487c4b4e@news.povray.org>
>        y = llCos(Rot.x)*y - llSin(Rot.x)*z;
>        z = llSin(Rot.x)*y + llCos(Rot.x)*z;

This is not going to work, because you are setting the new "y" value in the 
first line, then using it in the 2nd line (but you should be using the 
previous y value).

Try something like

x2 = x;
y2 = llCos(Rot.x)*y - llSin(Rot.x)*z;
z2 = llSin(Rot.x)*y + llCos(Rot.x)*z;

x = llSin(Rot.y)*z2 + llCos(Rot.y)*x2;
y = y2;
z = llCos(Rot.y)*z2 - llSin(Rot.y)*x2;

x2 = llCos(Rot.z)*x - llSin(Rot.z)*y;
y2 = llSin(Rot.z)*x + llCos(Rot.z)*y;
z2 = z;

npos = <x2,y2,z2>;


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From: Patrick Elliott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 15 Jul 2008 03:26:14
Message: <MPG.22e5fee72acf026d98a181@news.povray.org>
In article <487c4b4e@news.povray.org>, sco### [at] scottcom says...
> >        y = llCos(Rot.x)*y - llSin(Rot.x)*z;
> >        z = llSin(Rot.x)*y + llCos(Rot.x)*z;
> 
> This is not going to work, because you are setting the new "y" value in t
he 
> first line, then using it in the 2nd line (but you should be using the 
> previous y value).
> 
> Try something like
> 
> x2 = x;
> y2 = llCos(Rot.x)*y - llSin(Rot.x)*z;
> z2 = llSin(Rot.x)*y + llCos(Rot.x)*z;
> 
> x = llSin(Rot.y)*z2 + llCos(Rot.y)*x2;
> y = y2;
> z = llCos(Rot.y)*z2 - llSin(Rot.y)*x2;
> 
> x2 = llCos(Rot.z)*x - llSin(Rot.z)*y;
> y2 = llSin(Rot.z)*x + llCos(Rot.z)*y;
> z2 = z;
> 
> npos = <x2,y2,z2>;
>  
Figured it was "something" like that. The code for it, on the site, gave 
"no" clue how/where to use the original values, at all. Almost as bad as 
the stupid bartender HUD I picked up, which the clowns had popping a 
"display next set of items" message to 12 different prims, only one of 
which "had" a list to display, and then failing to "check" of the list 
was empty. lol Nothing like spamming 11 empty menus to the client for 
every page of "people" you had to give drinks out to.

I sometimes wonder if some people use "any" logic when trying writing 
documentation, examples, or just coding. lol

Thanks for the fix.

-- 
void main () {

    if version = "Vista" {
      call slow_by_half();
      call DRM_everything();
    }
    call functional_code();
  }
  else
    call crash_windows();
}

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3D Content, and 3D Software at DAZ3D!</A>


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From: Patrick Elliott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 16 Jul 2008 01:42:42
Message: <MPG.22e72547d2aee12998a182@news.povray.org>
In article <MPG.22e5fee72acf026d98a181@news.povray.org>, 
sel### [at] rraznet says...
> 
> Thanks for the fix.
> 
Actually. It maybe works, and maybe doesn't. lol This is a good start 
though, since the real issue may be more subtle. If I am right about 
what is going wrong this time, then SL supports:

Rotate everything via base prim.
Rotate locally, as though the base prim moved, but only move the object.
Rotate the object, but not the base prim.

Obviously, this is "still" a problem if your intent is to rotate the 
third or forth object out from the center, like if you had body + upper 
arm + lower arm, etc., and you want to move the lower arm. (This would 
be, presumably an crane, or some other non-player object, just to be 
clear.) By using local rotation *and* SetPos, I may have, in effect, 
rotated the object to the Rot angle, by positioning it, then rotated it 
"again" by that angle, using SetLocalRot. Needless to say, this is 
"not" working as I had intended. lol I will have to experiment some more 
to see what is really going on.

But, if it is the problem, then at least this math lends itself to 
rotation at points "other" than the center of the objects, or around the 
base prim, given a "bit" of modification. So, it could be set up to 
rotate it at an object corner, a cylinders end cap, or any other 
arbitrary point, on or off, the object. Which is a "vast" improvement 
over the original situation. Just needs using "SetRot", instead of 
"SetLocalRot" to get the right angle for the objects own facing.

-- 
void main () {

    if version = "Vista" {
      call slow_by_half();
      call DRM_everything();
    }
    call functional_code();
  }
  else
    call crash_windows();
}

<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models,
 
3D Content, and 3D Software at DAZ3D!</A>


Post a reply to this message

From: Patrick Elliott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 16 Jul 2008 01:58:16
Message: <MPG.22e73bdde113168b98a183@news.povray.org>
Ok, there is a bug in your "fixed" math (mind you, I was also forgetting 
to convert to radians when doing the sin/cos, so that was what made it 
go completely insane the first attempt... This however, rotating on the 
Y axis, goes nuts:

vector Rot = <0,0,0>;

default
{
    state_entry()
    {
        llSetTimerEvent(0);
        llSetLocalRot(<0,0,0,0>);
        llSetPos(<1,1,1>);
    }
    
    on_rez(integer dummy)
    {
        llSetTimerEvent(0);
    }

    touch_start(integer total_number)
    {
        llSetTimerEvent(0.2);
    }
    
    timer()
    {
        vector pos = llGetLocalPos();
        vector bpos = llGetRootPosition();
        llOwnerSay((string)pos);
        //llOwnerSay((string)bpos);
        
        vector npos;
        float x = pos.x;
        float y = pos.y;
        float z = pos.z;
        Rot = Rot + <0,1,0>;
        if (Rot.x > 359)
        {
            Rot.x = 0;
        }
        if (Rot.y > 359)
        {
            Rot.y = 0;
        }
        if (Rot.z > 359)
        {
            Rot.z = 0;
        }
        
        float x2 = x;
        float y2;
        float z2;
        y2 = llCos(Rot.x* DEG_TO_RAD)*y - llSin(Rot.x* DEG_TO_RAD)*z;
        z2 = llSin(Rot.x* DEG_TO_RAD)*y + llCos(Rot.x* DEG_TO_RAD)*z;
        
        y = y2;
        z = llCos(Rot.y* DEG_TO_RAD)*z2 - llSin(Rot.y* DEG_TO_RAD)*x2;
        x = llSin(Rot.y* DEG_TO_RAD)*z2 + llCos(Rot.y* DEG_TO_RAD)*x2;
        
        x2 = llCos(Rot.z* DEG_TO_RAD)*x - llSin(Rot.z* DEG_TO_RAD)*y;
        y2 = llSin(Rot.z* DEG_TO_RAD)*x + llCos(Rot.z* DEG_TO_RAD)*y;
        npos = <x2,y2,z2>;
        
        llSetPos(npos);
        //llSetLocalRot(llEuler2Rot(Rot * DEG_TO_RAD));
        //llSetRot(llEuler2Rot(Rot * DEG_TO_RAD));
    }
}

Note, this is using "Rot = Rot + <0,1,0>;", or changing the rotation by
 
one degree in the Y axis each time. The result is:

[22:41]  Object: <1.00000, 1.00000, 1.00000>
[22:41]  Object: <0.99969, 1.01760, 1.00000>
[22:41]  Object: <1.01607, 1.03549, 1.00000>
[22:41]  Object: <1.04878, 1.05396, 1.00000>
[22:41]  Object: <1.09741, 1.07327, 1.00000>
[22:41]  Object: <1.16148, 1.09371, 1.00000>
[22:41]  Object: <1.24037, 1.11553, 1.00000>
[22:41]  Object: <1.33332, 1.13897, 1.00000>
[22:41]  Object: <1.43941, 1.16427, 1.00000>
[22:41]  Object: <1.55757, 1.19163, 1.00000>
[22:41]  Object: <1.68650, 1.22125, 1.00000>
[22:41]  Object: <1.82472, 1.25329, 1.00000>
[22:41]  Object: <1.97058, 1.28788, 1.00000>
[22:41]  Object: <2.12223, 1.32512, 1.00000>
[22:41]  Object: <2.27763, 1.36508, 1.00000>
[22:41]  Object: <2.43464, 1.40778, 1.00000>
[22:41]  Object: <2.59100, 1.45322, 1.00000>
[22:41]  Object: <2.74437, 1.50135, 1.00000>
[22:41]  Object: <2.89242, 1.55206, 1.00000>
[22:41]  Object: <3.03286, 1.60524, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.16347, 1.66070, 1.00000>
[22:41]  Object: <3.15236, 1.71598, 1.00000>
[22:41]  Object: <3.12541, 1.77079, 1.00000>
[22:41]  Object: <3.08492, 1.82491, 1.00000>
[22:41]  Object: <3.03322, 1.87813, 1.00000>
[22:41]  Object: <2.97264, 1.93031, 1.00000>
[22:41]  Object: <2.90536, 1.98131, 1.00000>
[22:41]  Object: <2.83341, 2.03107, 1.00000>
[22:41]  Object: <2.75858, 2.07953, 1.00000>
[22:41]  Object: <2.68245, 2.12667, 1.00000>
[22:41]  Object: <2.60630, 2.17249, 1.00000>
[22:41]  Object: <2.53117, 2.21700, 1.00000>
[22:41]  Object: <2.45784, 2.26024, 1.00000>
[22:42]  Object: <2.38688, 2.30225, 1.00000>
[22:42]  Object: <2.31867, 2.34307, 1.00000>
[22:42]  Object: <2.25339, 2.38276, 1.00000>
[22:42]  Object: <2.19114, 2.42137, 1.00000>
[22:42]  Object: <2.13189, 2.45895, 1.00000>
[22:42]  Object: <2.07555, 2.49556, 1.00000>
[22:42]  Object: <2.02198, 2.53123, 1.00000>
[22:42]  Object: <1.97101, 2.56602, 1.00000>
[22:42]  Object: <1.92247, 2.59997, 1.00000>
[22:42]  Object: <1.87616, 2.63311, 1.00000>
[22:42]  Object: <1.83194, 2.66549, 1.00000>
[22:42]  Object: <1.78962, 2.69714, 1.00000>
[22:42]  Object: <1.74905, 2.72808, 1.00000>
[22:42]  Object: <1.71012, 2.75834, 1.00000>
[22:42]  Object: <1.67268, 2.78796, 1.00000>
[22:42]  Object: <1.63664, 2.81695, 1.00000>
[22:42]  Object: <1.60189, 2.84534, 1.00000>
[22:42]  Object: <1.56834, 2.87315, 1.00000>
[22:42]  Object: <1.53593, 2.90040, 1.00000>
[22:42]  Object: <1.50456, 2.92710, 1.00000>
[22:42]  Object: <1.47419, 2.95328, 1.00000>

In other words, it heads straight out to a corner, *then* starts 
rotating.

Rotation in the X and Z vectors works correctly (well, mostly, there 
seems to be some precision loss, maybe), though I still need to figure 
out how to make the prim face the "direction" that it is supposed to 
have moved to. Local rotation didn't seem to want to do that correctly.

Rotation in X:

[22:52]  Object: <1.00000, 1.00000, 1.00000>
[22:52]  Object: <1.00000, 0.98240, 1.01730>
[22:52]  Object: <1.00000, 0.94629, 1.05097>
[22:52]  Object: <1.00000, 0.88999, 1.09905>
[22:52]  Object: <1.00000, 0.81116, 1.15846>
[22:52]  Object: <1.00000, 0.70711, 1.22474>
[22:52]  Object: <1.00000, 0.57521, 1.29195>
[22:52]  Object: <1.00000, 0.41348, 1.35242>
[22:52]  Object: <1.00000, 0.22123, 1.39680>
[22:52]  Object: <1.00000, 0.00000, 1.41421>
[22:52]  Object: <1.00000, -0.24558, 1.39273>
[22:52]  Object: <1.00000, -0.50681, 1.32028>
[22:52]  Object: <1.00000, -0.77024, 1.18606>
[22:52]  Object: <1.00000, -1.01730, 0.98240>
[22:52]  Object: <1.00000, -1.22474, 0.70711>
[22:52]  Object: <1.00000, -1.36603, 0.36603>
[22:52]  Object: <1.00000, -1.41400, -0.02468>
[22:52]  Object: <1.00000, -1.34500, -0.43702>
[22:52]  Object: <1.00000, -1.14412, -0.83125>
[22:52]  Object: <1.00000, -0.81116, -1.15846>
[22:52]  Object: <1.00000, -0.36603, -1.36603>
[22:52]  Object: <1.00000, 0.14783, -1.40647>
[22:52]  Object: <1.00000, 0.66393, -1.24868>
[22:52]  Object: <1.00000, 1.09905, -0.88999>
[22:52]  Object: <1.00000, 1.36603, -0.36603>
[22:52]  Object: <1.00000, 1.39273, 0.24558>
[22:52]  Object: <1.00000, 1.14412, 0.83125>
[22:52]  Object: <1.00000, 0.64204, 1.26007>
[22:52]  Object: <1.00000, -0.02468, 1.41400>
[22:52]  Object: <1.00000, -0.70711, 1.22474>
[22:52]  Object: <1.00000, -1.22474, 0.70711>
[22:52]  Object: <1.00000, -1.41400, -0.02468>
[22:52]  Object: <1.00000, -1.18606, -0.77024>
[22:52]  Object: <1.00000, -0.57521, -1.29195>
[22:52]  Object: <1.00000, 0.24558, -1.39273>
[22:52]  Object: <1.00000, 1.00000, -1.00000>

This doesn't seem to be "exactly" right either, it seems to rotate more 
than the one degree I was attempting, so I need to work out why, but its 
way closer to what it should be doing than what "Rot = Rot + <0,1,0>;" 
ends up generating...

Was right about how the rotations worked though. This method is needed 
to rotate off of center, instead of just rotating around the prims own 
center...

This is "very" close to what I was trying to do, but, obviously, there 
is a bug some place in it. :(

-- 
void main () {

    if version = "Vista" {
      call slow_by_half();
      call DRM_everything();
    }
    call functional_code();
  }
  else
    call crash_windows();
}

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3D Content, and 3D Software at DAZ3D!</A>


Post a reply to this message

From: Patrick Elliott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 16 Jul 2008 02:00:18
Message: <MPG.22e73c57b051dca598a184@news.povray.org>
In article <MPG.22e72547d2aee12998a182@news.povray.org>, 
sel### [at] rraznet says...
> In article <MPG.22e5fee72acf026d98a181@news.povray.org>, 
> sel### [at] rraznet says...
> > 
> > Thanks for the fix.
> > 
> Actually. It maybe works, and maybe doesn't. lol This is a good start 
> though, since the real issue may be more subtle. If I am right about 
> what is going wrong this time, then SL supports:
> 
> Rotate everything via base prim.
> Rotate locally, as though the base prim moved, but only move the object.
> Rotate the object, but not the base prim.
> 
> Obviously, this is "still" a problem if your intent is to rotate the 
> third or forth object out from the center, like if you had body + upper
 
> arm + lower arm, etc., and you want to move the lower arm. (This would 
> be, presumably an crane, or some other non-player object, just to be 
> clear.) By using local rotation *and* SetPos, I may have, in effect, 
> rotated the object to the Rot angle, by positioning it, then rotated it
 
> "again" by that angle, using SetLocalRot. Needless to say, this is 
> "not" working as I had intended. lol I will have to experiment some more
 
> to see what is really going on.
> 
> But, if it is the problem, then at least this math lends itself to 
> rotation at points "other" than the center of the objects, or around the
 
> base prim, given a "bit" of modification. So, it could be set up to 
> rotate it at an object corner, a cylinders end cap, or any other 
> arbitrary point, on or off, the object. Which is a "vast" improvement 
> over the original situation. Just needs using "SetRot", instead of 
> "SetLocalRot" to get the right angle for the objects own facing.
> 
Was doing the sin/cos wrong. Ignore most of this. lol Still need to mod 
it to do "off of center on the object", but its a "hair" more complex 
than this, since the LocalRot isn't doing what I thought it did.

-- 
void main () {

    if version = "Vista" {
      call slow_by_half();
      call DRM_everything();
    }
    call functional_code();
  }
  else
    call crash_windows();
}

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3D Content, and 3D Software at DAZ3D!</A>


Post a reply to this message

From: scott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 16 Jul 2008 02:51:38
Message: <487d9a7a@news.povray.org>
> This however, rotating on the
> Y axis, goes nuts:

If you're rotating only the y axis (ie Rot.x and Rot.z are zero), then the y 
coordinate shouldn't change.

>        y2 = llCos(Rot.x* DEG_TO_RAD)*y - llSin(Rot.x* DEG_TO_RAD)*z;

Since Rot.x is zero, the above line is equivalent to y2 = y

>        y = y2;

Obvious.

>        y2 = llSin(Rot.z* DEG_TO_RAD)*x + llCos(Rot.z* DEG_TO_RAD)*y;

Again, since Rot.z should be zero here, this line is again equivalent to y2 
= y

> [22:41]  Object: <1.00000, 1.00000, 1.00000>
> [22:41]  Object: <0.99969, 1.01760, 1.00000>

I would suggest you check the values of Rot.x and Rot.z in your code, and 
also the xyz coords after each rotation - none of them should modify the y 
coordinate if only Rot.y is non-zero.


Post a reply to this message

From: Patrick Elliott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 16 Jul 2008 04:47:05
Message: <MPG.22e763577812f6af98a185@news.povray.org>
In article <487d9a7a@news.povray.org>, sco### [at] scottcom says...
> > This however, rotating on the
> > Y axis, goes nuts:
> 
> If you're rotating only the y axis (ie Rot.x and Rot.z are zero), then th
e y 
> coordinate shouldn't change.
> 
> >        y2 = llCos(Rot.x* DEG_TO_RAD)*y - llSin(Rot.x* DEG_TO_RAD)*z;
> 
> Since Rot.x is zero, the above line is equivalent to y2 = y
> 
> >        y = y2;
> 
> Obvious.
> 
> >        y2 = llSin(Rot.z* DEG_TO_RAD)*x + llCos(Rot.z* DEG_TO_RAD)*y;
> 
> Again, since Rot.z should be zero here, this line is again equivalent to 
y2 
> = y
> 
> > [22:41]  Object: <1.00000, 1.00000, 1.00000>
> > [22:41]  Object: <0.99969, 1.01760, 1.00000>
> 
> I would suggest you check the values of Rot.x and Rot.z in your code, and
 
> also the xyz coords after each rotation - none of them should modify the 
y 
> coordinate if only Rot.y is non-zero.
>  

Ok. First off, I am an idiot. The code is based on rotating an object at 
a known point, so in theory, I should, I think, always start x,y,z at 
1,1,1, the "start point", where the object was in the first place. That 
may be having some effect, otherwise, I need to only rotate it by N 
degrees every time, not "increase" N each pass. I suppose that "may" be 
causing this odd behavior somehow, though, I can't imagine how, since 
the vector length for any point on a rotation starting at 1,1,1 *should 
be* the same, no matter what position the object occupies, i.e., the 
vector length should still average to a line length of "1", not 3, or 
what ever it comes out to.

It also seems damn strange to me, if the rotation values where causing 
it, for Y to be producing that effect, either by itself, or combined 
with any other values.. Hmm.. Will have to get back to you on what 
happens when I fix the goof I made in trying to "read" the position 
every time, instead of once, but that will be tomorrow. Its after 2am as 
of posting this, and I was half asleep when I realized what one of the 
places I had screwed up was. lol

-- 
void main () {

    if version = "Vista" {
      call slow_by_half();
      call DRM_everything();
    }
    call functional_code();
  }
  else
    call crash_windows();
}

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From: Patrick Elliott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 16 Jul 2008 21:58:05
Message: <MPG.22e82557b7416a1b98a186@news.povray.org>
OK, this code, finally, mostly works:

vector Rot;
vector RotChange;
vector RotAngle;
float x;
float y;
float z;

default
{
    state_entry()
    {
        llSetTimerEvent(0);
        llSetLocalRot(<0,0,0,0>);
        llSetPos(<1,1,1>);
        Rot = <0,0,0>;
	 //Change to adjust how it moves.
        RotChange = <10,0,0>;
    }
    
    on_rez(integer dummy)
    {
        llSetTimerEvent(0);
    }

    touch_start(integer total_number)
    {
        llSetTimerEvent(0.1);
        vector pos = llGetLocalPos();   
        x = pos.x;
        y = pos.y;
        z = pos.z;
    }
    
    timer()
    {
        vector bpos = llGetRootPosition();
        //llOwnerSay((string)pos);
        //llOwnerSay((string)bpos);
        
        vector npos;
        Rot = Rot + RotChange;
        RotAngle = Rot * DEG_TO_RAD;
        if (Rot.x > 359)
        {
            Rot.x = 0;
        }
        if (Rot.y > 359)
        {
            Rot.y = 0;
        }
        if (Rot.z > 359)
        {
            Rot.z = 0;
        }
        
        float xx = x;
        float xy = llCos(RotAngle.x)*y - llSin(RotAngle.x)*z;
        float xz = llSin(RotAngle.x)*y + llCos(RotAngle.x)*z;
        
        float yy = xy;
        float yz = llCos(RotAngle.y)*xz - llSin(RotAngle.y)*xx;
        float yx = llSin(RotAngle.y)*xz + llCos(RotAngle.y)*xx;
        
        float zx = llCos(RotAngle.z)*yx - llSin(RotAngle.z)*yy;
        float zy = llSin(RotAngle.z)*yx + llCos(RotAngle.z)*yy;
        float zz = yz;
        npos = <zx,zy,zz>;
        
        llSetPos(npos);
        llSetLocalRot(llEuler2Rot(Rot * DEG_TO_RAD));
        //llSetRot(llEuler2Rot(Rot * DEG_TO_RAD));
    }
}

However, I still get some real "odd" behavior if I try to do more than 
one direction at a time, like RotChange = <10,0,10>. Instead of 
following the expected path, it seems to curve off in the wrong 
direction, back to the starting point, then around in a curve, ending 
up.. Well, its impossible to describe exactly, but, suffice to say that 
instead of looping from 1,1,1, ending up at a point diagonal to where it 
started, it instead ends up following some other odd path, which doesn't 
fit what I expect to see. Would this be the so called "gimble lock" 
issue that is sometimes described? I am more confused by what is going 
wrong now, or even if it "is" going wrong, than I was before. lol


-- 
void main () {

    if version = "Vista" {
      call slow_by_half();
      call DRM_everything();
    }
    call functional_code();
  }
  else
    call crash_windows();
}

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3D Content, and 3D Software at DAZ3D!</A>


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From: scott
Subject: Re: Trying to code an "offset rotation" for SL.
Date: 17 Jul 2008 03:08:54
Message: <487ef006$1@news.povray.org>
>        if (Rot.x > 359)
>        {
>            Rot.x = 0;
>        }

I think that previous line would be better written as:

if( Rot.x >= 360 )
{
 Rot.x = Rot.x - 360;
}

It will give the correct transition as it passes 360 degrees.

> However, I still get some real "odd" behavior if I try to do more than
> one direction at a time, like RotChange = <10,0,10>. Instead of
> following the expected path, it seems to curve off in the wrong
> direction,

OK, I missed the fact that your llEuler2Rot() function probably is expecting 
Euler angles, which are different from rotations about the global xyz axes 
(like POV uses for "rotate" and what you are doing in those 3 groups of trig 
functions).  To make matters worse, Euler angles are not a universally 
defined standard, does it say anything about the definition in the function 
help?

Try something like the following (hopefully no typos!), which rotates the 
point based on the most standard Euler angle system:

        float xx = llCos(RotAngle.x)*x - llSin(RotAngle.x)*y;
        float xy = llSin(RotAngle.x)*x + llCos(RotAngle.x)*y;
        float xz = z;

        float yx = xx;
        float yy = llCos(RotAngle.y)*xy - llSin(RotAngle.y)*xz;
        float yz = llSin(RotAngle.y)*xy + llCos(RotAngle.y)*xz;

        float zx = llCos(RotAngle.z)*yx - llSin(RotAngle.z)*yy;
        float zy = llSin(RotAngle.z)*yx + llCos(RotAngle.z)*yy;
        float zz = yz;
        npos = <zx,zy,zz>;

Hopefully that method of rotating will match up with the llEuler2Rot 
function.

As always, more info on Wikipedia about Euler angles:

http://en.wikipedia.org/wiki/Euler_angles


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