Orienting joints with MEL?

[tom hain]

Hi David,

i did the same, I just duplicated the chain and modified it, never thought about something else.
I guess, the reason why you don`t get the same result by setting the attribs, is you dont` t really set --all-- attribs.
the joint Node is inherited from the transformNode. if you see the Node Doku, transform has some more attributes.
if you freeze transformation for example your translate values are 0 0 0. but your "real translation" is the translate minus transMinusRotatePivot. this compensates your frozen values.
try your script again, make shure all the translate values are copied.

tell me please if it works

cheers

t

[ragtag]

If you want to orient joints to a predefined position. You could do this with an aim constraints.

1. De-parent the joint, so it's standing alone (no children)
2. Aim constraint it to it's previous child joint, using either a locator as an upvector or a world axis.
3. Delete the aim constraint (and up vector object if any).
4. Set the joint orient attributes of the joint to it's rotate values.
5. Set the rotate values to zero.

This, of course, depends on some kind of up vector. Though that might be easy to define.

Here's a snippet from the sciprt I'm working on that does this (it won't run as written here, as it needs the rest of the script, but might give you some idea):


// Create joints at even intervals along the curve
string $spine[];
for ($i=0;$i<101;$i=$i+10)
{
currentTime $i;
float $x = `getAttr ($group +".tx")`;
float $y = `getAttr ($group +".ty")`;
float $z = `getAttr ($group +".tz")`;
select -cl;
$spine[$i/10] = `joint -name ("spine_"+ $i/10) -position $x $y $z`;
setAttr .displayLocalAxis 1; // !!! Debug, remove later
}
// Orient joints correctly
for ($i=0;$i<10;$i++)
{
string $tempAim[] = `aimConstraint -worldUpVector 0 0 -1 -worldUpType "vector" $spine[$i+1] $spine[$i]`;
delete $tempAim;
float $rot[] = `getAttr ($spine[$i]+".r")`;
//setAttr ($spine[$i]+".ra") $rot[0] $rot[1] $rot[2];
setAttr ($spine[$i]+".jo") $rot[0] $rot[1] $rot[2];
setAttr ($spine[$i]+".r") 0 0 0;
}
// Parent the joints together
for ($i=0;$i<10;$i++)
{
parent $spine[$i+1] $spine[$i];
}


Ragnar

[dwalden74]

Hi Ragnar-

constraint it to it's previous child joint

Don´t you mean "successive joint" here? I´ll have to see if this works in my case. What I want to do is get the joint orientation from an existing chain in which the joints have already been oriented correctly. Currently my script works by duplicating the original chain and removing joints to create a more simplified chain (joint orientations are therefore preserved).

:beer:
David

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