Fix T82455: vec_roll_to_mat3_normalized returns NaN when nor close to -Y.

In this case theta is completely unsafe to use, so a different
threshold based on x and z has to be used to avoid division by zero.

Ref D9551

Fix T82455: vec_roll_to_mat3_normalized returns NaN when nor close to -Y.

In this case theta is completely unsafe to use, so a different
threshold based on x and z has to be used to avoid division by zero.

Ref D9551

Make keyframe inserts/removals less verbose when called from python.

Following operators now only report messages back when they are called via their invoke-methods:

- ANIM_OT_keyframe_insert
- ANIM_OT_keyframe_insert_by_name
- ANIM_OT_keyframe_insert_menu
- ANIM_OT_keyframe_delete
- ANIM_OT_keyframe_clear_v3d
- ANIM_OT_keyframe_delete_v3d

Also removed the attribute confirm_success from the following operators:

- ANIM_OT_keyframe_insert
- ANIM_OT_keyframe_insert_by_name
- ANIM_OT_keyframe_insert_menu
- ANIM_OT_keyframe_delete
- ANIM_OT_keyframe_delete_by_name

Note: addons/scripts possibly need to be updated if they use the above operators AND set the "confirm_success" attribute

Reviewed By: campbellbarton

Differential Revision: https://developer.blender.org/D12697

Add an option to silence bpy.ops.anim.keyframe_delete_v3d when used in Addons

The issues:

1.) When we want to remove keyframes from a range of frames in an
action,
then we can use bpy.ops.anim.keyframe_delete_v3d to remove the keys
frame by frame. However, whenever the operator hits a frame with no
keyframes, then it generates an error. While when it hits a frame
with keyframes, then it reports the numbner of removed keys.

This creates a lot of unnecessary noise in the Blender console.

2.) Furthermore a related issue is that WM_event_add_notifier() is
called also when no frames where removed. This seems to significantly
slow down the removal of keyframes in a range of frames at least
when i use vscode for debugging.

A proposal for improvement:
This patch adds an attribute 'confirm_success' which controls
if the operator reports back what it did (or did not) while
executing. Silent mode would then be called like this:

bpy.ops.anim.keyframe_delete_v3d(confirm_success=False)

Note: confirm_success is True by default so this patchj does not
change the behavior of Blender, it only gives the option to scripts.

3.) Personal note:
I have chosen the attribute name to be equal as it is used
in other related operators. However i rather would rename the
attribute to "verbose" (preferred) or "with_confirm". But i let this
to be decided by the reviewers. Thanks for your time to review!

Reviewed By: campbellbarton

Differential Revision: https://developer.blender.org/D12629

Add a reason for why an Addon can not be loaded. This change gives a more detailed explanation of the issue and may help the Addon Developer to identify what exactly needs to be changed.

The current message 'addon not loaded' is a bit too sparse.

Differential Revision: https://developer.blender.org/D11655

Add a reason for why an Addon can not be loaded. This change gives a more detailed explanation of the issue and may help the Addon Developer to identify what exactly needs to be changed.

The current message 'addon not loaded' is a bit too sparse.

Differential Revision: https://developer.blender.org/D11655

Collada import: use black for Base Color when missing <diffuse>

Treat a missing <diffuse> the same as a black diffuse color.

The easiest way to see this bug is with a Collada shader like

```
<constant>
<emission>
<color sid="emission">1 0 0 1</color>
</emission>
</constant>
```

The Collada spec says this should be just

```
color = <emission>
```

ie. red everywhere. The importer slots the red into the Principled Emission socket, but since it leaves the Base Color as the default off-white, this is added to red, and the material looks white-pink in the light and red only in the shadows.

Putting black in the Base Color makes it look red everywhere.

D10939 will also eliminate the much-less-noticeable specular term for this case.

Reviewed By: gaiaclary

Differential Revision: https://developer.blender.org/D10941

refactor: minor changes to previous commit
- rename boolean is_zero by more descriptive has_specularity
- add some clarifying comments (and TODO)

fix T83880: Added check for valid context object to avoid null pointer exception when no object in scene

refactor vec_roll_to_mat3_normalized() for clarity

the function vec_roll_to_mat3_normalized() has a bug as described in T82455. This Differential is only for refactoring the code such that it becomes more clear what the function does and how the bug can be fixed. This differential is supposed to not introduce any functional changes.

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D9410