Rotate object using 2 vectors

Coding Python Support
1

Hi!
I have 2 perpendicular vectors. How I can rotate object using this vectors?

2

using two perpendicular vectors, you can get a third axis by calculating the cross product of the first and second axis.

up_vector = vec1.normalized()
right_vector = vec2.normalized()
fwd_vector = up_vector.cross(right_vector)

once you have three cartesian axes vectors you can easily create a 3x3 rotation matrix once you know how a blender matrix is composed

and lastly, once you’ve got a 3x3 rotation matrix, you can transform your object using matrix multiplication
oldmat.to_3x3() @ new_rot.to_3x3()

2 Likes
3

Yes, I can get 3 vector, but how rotate object, using this 3 vectors?

4

It’s get bad result

        bpy.ops.transform.rotate(value=math.acos(vector_speed[0]), orient_axis='X', orient_type='GLOBAL', orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)))
        bpy.ops.transform.rotate(value=math.acos(vector_speed[1]), orient_axis='Y', orient_type='GLOBAL', orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)))
        bpy.ops.transform.rotate(value=math.acos(vector_speed[2]), orient_axis='Z', orient_type='GLOBAL', orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)))
5

I get vector using this code. But how rotate my object?

def make_matrix(v1, v2, v3):
    v1 = array_to_vector(v1)
    v2 = array_to_vector(v2)
    v3 = array_to_vector(v3)
    a = v2-v1
    b = v3-v1

    c = a.cross(b)
    if c.magnitude>0:
        c = c.normalized()
    else:
        raise BaseException("A B C are colinear")

    b2 = c.cross(a).normalized()
    a2 = a.normalized()
    m = mathutils.Matrix([a2, b2, c]).transposed()
    s = a.magnitude
    m = mathutils.Matrix.Translation(v1) * mathutils.Matrix.Scale(s,4) * m.to_4x4()
    return m
6

It’s work

vector_i = vector_speed
        vector_j = normal_for_plane
        vector_k = new_normal
        vertice0 = [0, 0, 0]        
        matrix = np.array([[vector_i[0], vector_i[1], vector_i[2], 0],
                        [vector_j[0], vector_j[1], vector_j[2], 0],
                        [vector_k[0], vector_k[1], vector_k[2], 0],
                        [vertice0[0], vertice0[1], vertice0[2], 1]]).T
                        
        print(444, matrix)
        print(555, mathutils.Matrix(matrix))
        print(666, mathutils.Matrix(matrix).decompose())
        loc, rot, scale = mathutils.Matrix(matrix).decompose()
        print(777, rot, rot.w, rot.x, rot.y, rot.z)
        bpy.context.active_object.rotation_mode = 'QUATERNION'
        bpy.context.active_object.rotation_quaternion = rot