How to save an object's transforms relative to another object?

[Anonymous]

In mel, how would you save object x's transform data (translation and rotation) relative to another object y, and put this into a variable?

In maxscript, I could get this relationship by:

matrix = x.transform * inverse y.transform

Then:

z.transform = matrix * y.transform

Obj z would snap to the translation and rotation of x relative to y.

It is not clear how to do this in mel, using the xform, getAttr or setAttr commands. Does anybody know how?

Thanks!

[Anonymous]

First of all you need to make sure that node's type is 'transform'

if(`nodeType  $node` == "transform"){
  //grab matrix there
}

if node is not transform but shape you may try to find its transfomation node:

string $parents[] = `listRelatives -fullPath -parent $node`;
$transform = $parents[0];

and then grab the matrix from the attribute 

float $m[] = `getAttr ($transform+".xformMatrix")`;

you can also grab this way inverseMatrix, worldInverseMatrix or parentInverseMatrix.
or you can use xfrom command

float $m[] = `xform -q -m $transform`;

however in both cases you get an array of 16 floats and you need to 
convert it to MEL matrix to perform maxtrix*point multiplication

matrix $mt[4][4] = <<$m[0], $m[1], $m[2], $m[3];
$m[4], $m[5], $m[6], $m[7];
$m[8], $m[9], $m[10], $m[11];
$m[12], $m[13], $m[14], $m[15]>>;

Hope it helps. Not so handy as in MaxScript 😉