How can I delete all custom transform orientations?

Question

I'm trying to update a script I used in 2.79 to delete all custom transform orientations (CTOs).

The new API replaced bpy.context.scene.transform_orientations with bpy.context.scene.transform_orientations_slots. The problem is, for some reason, this is returning only the active CTO, not a list of the CTOs that I created. I couldn't find a way to return a list of CTOs so I can later iterate through them and delete them.

Tried:

Researching the matter, the closest thing I could find is bpy.ops.transform.select_orientation(orientation="some_CTO_name").

However this is not useful in my case, since the argument will only accept a string enum.

Also the info window isn't helping. When I change the Transform Orientation manually, the listener is printing bpy.context.scene.type = "TO_Name". Trying to use this in the console or the script will throw an AttributeError: 'Scene' object has no attribute 'type'.

The Script:

Following is the script. If you try it, it will only delete the CTO if it's already active. My question is, how to get the list of the CTOs?

import bpy
orient = bpy.context.scene.transform_orientation_slots
views = [area.spaces.active for area in bpy.context.screen.areas if area.type == 'VIEW_3D']
areas = [area for area in bpy.context.window.screen.areas if area.type == 'VIEW_3D']

for o in orient:
    if views and areas:
        views[0] = o
        override = bpy.context.copy()
        override['area']= areas[0]
        try:
            bpy.ops.transform.delete_orientation(override)
        except:
            pass

Answer 1

I was trying to solve the same problem, came up with this workaround.

If we tried to set transform_orientation_slots[0].type to a non existent value, we get this error:

TypeError: bpy_struct: item.attr = val: enum "" not found in ('GLOBAL', 'LOCAL', 'NORMAL', 'GIMBAL', 'VIEW', 'CURSOR', 'Cub', 'Cube', 'Cube.001', 'Cube.002', 'Cube.003', 'Cube.004', 'Cube.005', 'Cube.006', 'Cube.007', 'Cube.008', 'Cube.009', 'Cube.010', 'Cube.011', 'Cube.012')

The idea is to try and set that property, catch the error message, do string manipulation, and have a list of transform orientations.

After that we loop through custom orientations, set the transform orientation to it, and execute bpy.ops.transform.delete_orientation(), the script seems to be working well,

import bpy

try:
    bpy.context.scene.transform_orientation_slots[0].type = ""
except Exception as inst:
    transforms = str(inst).split("'")[1::2]

transform_list = list(transforms)
for enum_type in transform_list[7:]: # The 7 first orientations are builtins
    bpy.context.scene.transform_orientation_slots[0].type = enum_type
    bpy.ops.transform.delete_orientation()

I really hope there's a better solution if anyone has, I tried bl_rna["type"].enum_items, but it just returns the default orientations, not the custom ones, perhaps I'm missing something.

Answer 2

As for Blender 3.6 the script by @iyad-ahmed stopped working because Blender added new builtin orientation PARENT.

Previous script was relying that there will be exactly 6 builtins, I've updated the script so that it will get the actual list of builtin transformations so it won't break the next time Blender adds/removes new transformation.

PS there is still no other way to get list of all custom orientations besides parsing exception message and excluding builting.

import bpy

context = bpy.context
transform_slots = context.scene.transform_orientation_slots
builtin_transforms = [i.identifier for i in bpy.types.TransformOrientationSlot.bl_rna.properties['type'].enum_items]

# hacky (but the only way) to get the all available transforms
try:
    context.scene.transform_orientation_slots[0].type = ""
except Exception as inst:
    transforms = str(inst).split("'")[1::2]

for transform in transforms:
    if transform in builtin_transforms:
        continue
    transform_slots[0].type = transform
    bpy.ops.transform.delete_orientation()

Answer 3

orient_slot = bpy.context.scene.transform_orientation_slots[0]
custom = orient_slot.custom_orientation
custom.matrix

reference: https://blenderartists.org/t/2-80-cheat-sheet-for-updating-add-ons/1148974