random rotation around normal

[Anno]

Hi,
I'm building a scatter tool for maya that uses nparticles and an instancer to distribute geometry in the scene.
I built my own sampler that basically returns a point array which gets fed into the particle system.
Alongside the point array i also get a normal array which I can use to calculate rotation values that match to the surface normal direction.
I achieve this my doing the following:

normal = n[i] # MVector, surfacenormal
world = OpenMaya.MVector(0, 1, 0)
rot_quat = OpenMaya.MQuaternion(world, n[i], normal_weight)

rotation = OpenMaya.MVector(math.degrees(rot_quat.asEulerRotation().x), math.degrees(rot_quat.asEulerRotation().y), math.degrees(rot_quat.asEulerRotation().z))
self.rotation_pp.append(rotation)

What I want to do now is to randomly rotate each instance by a certain amount of degree around its "local" x, y and z axis.

Can somebody point me towards the right direction how I can get the desired result?

thanks a lot,
Anno

[Anno]

Hi again,

I found a solution so if someone is interested.

I create a new transform matrix and fill it with random values.

Then I can post-multiply the matrix by a matrix I get from the quaternion.

From the resulting matrix I can get my new rotation values.

rand_r = (10,360,10)
normal = n[i]

world = OpenMaya.MVector(0, 1, 0)

quat = OpenMaya.MQuaternion(world, n[i], normal_weight)

r_x = math.radians(random.uniform(-rand_r[0], rand_r[0]))
r_y = math.radians(random.uniform(-rand_r[1], rand_r[1]))
r_z = math.radians(random.uniform(-rand_r[2], rand_r[2]))


mat = OpenMaya.MTransformationMatrix()


util = OpenMaya.MScriptUtil()
util.createFromDouble(r_x,r_y,r_z)
r_i = util.asDoublePtr()
mat.setRotation(r_i, OpenMaya.MTransformationMatrix.kXYZ)


mat = mat.asMatrix() * quat.asMatrix()

Cheers,

Anno