Get var from def to use in another def

Question

Got this def I would like to use for multiple other defs in the same file

def matrix1():
    # create a location matrix
    mat_loc = mathutils.Matrix.Translation((-0.0, -0.0, -0.0))

    # create an identitiy matrix
    mat_sca = mathutils.Matrix.Scale(0.5, 4, (0.0, 0.0, 1.0))
    mat_sca1 = mathutils.Matrix.Scale(0.0, 4, (0.0, 0.0, 0.0))

    # create a rotation matrix
    mat_rot = mathutils.Matrix.Rotation(math.radians(90.0), 4, "Y")

    # combine transformations
    mat_out = mat_loc @ mat_rot @ mat_sca
    mat_out1 = mat_loc @ mat_rot

How can I "import" the combined transformation (mat_out or mat_out1) into another def?

def add_mesh(self, context):

    mesh = bpy.data.meshes.new("mesh")
    bm = bmesh.new()

    ret = bmesh.ops.create_circle(
        bm,
        segments=32,
        radius=1,
        matrix=mat_out1, #<-- this one gives error that mat_out1 is not defined
    )

I also tried to import def matrix but that also did not work.

Answer 1

Although Marty Fouts' solution works, you shouldn't use global variables. Why not? Because you have no "control" over these variables. It is very hard to debug and find mistakes in your program (if it gets bigger and bigger) and everybody can change them. Of course, if you have just 1 script with 20 lines of code, it's ok. But if you want to reuse your scripts, you should use a clean solution.

So you should work with e.g. a def which return values like so:

import bpy
import mathutils
import math

def matrix1():
    # create a location matrix
    mat_loc = mathutils.Matrix.Translation((-0.0, -0.0, -0.0))

    # create an identitiy matrix
    mat_sca = mathutils.Matrix.Scale(0.5, 4, (0.0, 0.0, 1.0))
    mat_sca1 = mathutils.Matrix.Scale(0.0, 4, (0.0, 0.0, 0.0))

    # create a rotation matrix
    mat_rot = mathutils.Matrix.Rotation(math.radians(90.0), 4, "Y")

    # combine transformations
    return mat_loc @ mat_rot @ mat_sca, mat_loc @ mat_rot




def add_mesh(self, context):

    mesh = bpy.data.meshes.new("mesh")
    bm = bmesh.new()

    matout, matout1 = matrix1()

    ret = bmesh.ops.create_circle(
        bm,
        segments=32,
        radius=1,
        matrix=matout1
    )

Answer 2

Here is one solution:

def matrix1():
    global mat_out
    global mat_out1
    # create a location matrix
    mat_loc = mathutils.Matrix.Translation((-0.0, -0.0, -0.0))

    # create an identitiy matrix
    mat_sca = mathutils.Matrix.Scale(0.5, 4, (0.0, 0.0, 1.0))
    mat_sca1 = mathutils.Matrix.Scale(0.0, 4, (0.0, 0.0, 0.0))

    # create a rotation matrix
    mat_rot = mathutils.Matrix.Rotation(math.radians(90.0), 4, "Y")

    # combine transformations
    mat_out = mat_loc @ mat_rot @ mat_sca
    mat_out1 = mat_loc @ mat_rot

By declaring the two matrices as global they will become available to use in the add_mesh function.

It really is a question about Python and not Blender.