# quaternion in c4d[Solved]

On 03/02/2013 at 14:43, xxxxxxxx wrote:

Hi

i am trying to import some tracking data (faceshift) into c4d.
everything works fine, except that i can not get the head-rotation work properly.

the head rotation i get from faceshift is in quaternion format and consist of 4 float values (x,y,z,w)

i tried doing something like this:

newMatrix=c4d.utils.RotAxisToMatrix(c4d.Vector(x,y,z),w)

i tried a lot with swapping or negating the values x,y,z and w, but had no luck so far.

i know that faceshift and c4d do not use the same coordinates systems (left handed vs right handed), because to get the head-translation correctly i need to negate the z-value.

hope someone can show me the way....

On 03/02/2013 at 15:55, xxxxxxxx wrote:

OK I solved it myself:

Here is how i got it working:

newMatrix = quaternionToMatrix(x,y,z,w)

def quaternionToMatrix(x,y,z,w) :
xx      = x * x;
xy      = x * y;
xz      = x * z;
xw      = x * w;
yy      = y * y;
yz      = y * z;
yw      = y * w;
zz      = z * z;
zw      = z * w;
vec1=c4d.Vector()
vec2=c4d.Vector()
vec3=c4d.Vector()
vecOff=c4d.Vector()
vec1.x  = 1 - 2 * ( yy + zz );
vec1.y  =     2 * ( xy - zw );
vec1.z  =     2 * ( xz + yw );
vec2.x  =     2 * ( xy + zw );
vec2.y  = 1 - 2 * ( xx + zz );
vec2.z  =     2 * ( yz - xw );
vec3.x  =     2 * ( xz - yw );
vec3.y  =     2 * ( yz + xw );
vec3.z = 1 - 2 * ( xx + yy );
newMatrix=c4d.Matrix(vecOff,vec1,vec2,vec3)
return newMatrix

here is the link where i found the function:
http://web.archive.org/web/20041029003853/http://web.archive.org/web/20041029003853/http://www.j3d.org/matrix_faq/matrfaq_latest.html#Q54