Getting A Vector From Rotation

[naughty]

Hey.. I'm sure I've done this before but I'm drawing a blank now, and the only other post I could find on the subject involved calculating it with maths offline.. and I need it for a connectAttr statement...

basically I have a node which has a float3 attribute that requires a normalized vector (i.e. 0 0 1)
I need to connectAttr a directional Lights direction to this attribute like so:

connectAttr directionalLight.rotate myNode.directionVector;

but of course this doesn't work as the objects's rotation is not a vector. Does anybody know if there is a utility node that I can put between the two nodes to do this conversion..? I tried vectorProduct but it didn't seem to work.. maybe I wasn't using it correctly.?

:nathaN

[ewerybody]

I have a little proc that rotates vectors for me:
CODE
global proc float[] rotateVector(float $vx, float $vy, float $vz, float $rx, float $ry, float $rz)
{
    float $temp, $sx, $cx, $sy, $cy, $sz, $cz;

    $rx = deg_to_rad($rx);
    $ry = deg_to_rad($ry);
    $rz = deg_to_rad($rz);

    $sx = sin($rx);
    $cx = cos($rx);
    $sy = sin($ry);
    $cy = cos($ry);
    $sz = sin($rz);
    $cz = cos($rz);

    $temp = $vy * $cx - $vz * $sx;
    $vz   = $vy * $sx + $vz * $cx;
    $vy   = $temp;

    $temp = $vz * $sy + $vx * $cy;
    $vz   = $vz * $cy - $vx * $sy;
    $vx   = $temp;

    $temp = $vx * $cz - $vy * $sz;
    $vy   = $vx * $sz + $vy * $cz;
    $vx   = $temp;

    float $resV[] = {$vx, $vy, $vz};
    normalize($resV);
    return $resV;
}

I use it quite often. You tell it the vector you have and then the rotation you want to perform and it returns you a floatArray with the rotated vector:CODE
float $rotVector[] = rotateVector 0 0 1 $shotRot[0] $shotRot[1] $shotRot[2];
I don't know if this helps.. but thats my idea.

Actually I don't have a clue how it really works. I just got such a function in C++ from a friend and translated it into mel ;]

[joojaa]

yes off course but theres a easier way. (by the way how it works is explained here).

Make the light aim it at a transform connect ty vector to the transforms position. (you can then group them togethera nd move teh group if you wish)

Alternatively use just the aim constraint and affect the aim vector either way iits what aim does. either way maya does not realy care if its normalized or not.

[naughty]

that's very nice Ewerybody, thanks.. but unfortunately it's of no help here. I have multiple ways of getting the light's vector (its matrix has it just sitting there ready for querying).. what I need is a method to connect it as attributes so the user can drive another object's attribute that is a float3, but requires 3 values that make up a normalized vector.

Maya might not care if the vector is normalized but cg code sure does.

Joojaa, I tried looking into using aimConstraint but I couldn't figure out how to set one up without relying on a target object, which is no good because then the light cannot be moved and rotated freely by the users..

there surely must be a node than I can simply connect the light to, and have it output a direction vector (preferably as 3 floats!)..?

no?

:nathaN