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Regression: Python: World matrix for newly created objects is not identity #119250

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opened 2024-03-09 14:20:59 +01:00 by Vitalii-2 · 11 comments
Vitalii-2 commented 2024-03-09 14:20:59 +01:00
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System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 551.76

Blender Version
Broken: version: 4.2.0 Alpha, branch: main, commit date: 2024-02-23 23:00, hash: 06d3627c4398
Worked: version: 4.2.0 Alpha, branch: main, commit date: 2024-02-09 09:37, hash: e20b2d2fb947

Short description of error
Newly crated objects via python (bpy.data.objects.new() ) have degenerate (all 0) world matrix matrix_world instead of identity.

Exact steps for others to reproduce the error
Run script in the attached file. The script creates new object and compares basis and world matrices to identity.
On 4.2.0alpha script raises and exception when comparing world matrix to identity.
On older stable versions no exceptions are raised.

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 551.76 **Blender Version** Broken: version: 4.2.0 Alpha, branch: main, commit date: 2024-02-23 23:00, hash: `06d3627c4398` Worked: version: 4.2.0 Alpha, branch: main, commit date: 2024-02-09 09:37, hash: `e20b2d2fb947` **Short description of error** Newly crated objects via python (`bpy.data.objects.new()` ) have degenerate (all 0) world matrix `matrix_world` instead of identity. **Exact steps for others to reproduce the error** Run script in the attached file. The script creates new object and compares basis and world matrices to identity. On 4.2.0alpha script raises and exception when comparing world matrix to identity. On older stable versions no exceptions are raised.
matrix_world.blend
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Vitalii-2 added the
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Iliya Katushenock changed title from Regression, Python: world matrix for newly created objects is not identity to Regression: Python: World matrix for newly created objects is not identity 2024-03-09 14:30:51 +01:00
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Roman Markov commented 2024-03-10 00:31:28 +01:00
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import subprocess

def get_python_expr(func, *args, **kwargs):
    """ Does not work with `shell=True`. """

    import inspect
    import textwrap
    import json

    expr = [textwrap.dedent(inspect.getsource(func))]

    args_json = repr(json.dumps(args))
    kwargs_json = repr(json.dumps(kwargs))

    expr.append('import json')
    expr.append(f'args = json.loads({args_json})')
    expr.append(f'kwargs = json.loads({kwargs_json})')
    expr.append(f'{func.__name__}(*args, **kwargs)')

    return '\n'.join(expr)


def import_model(filepath):
    import bpy

    bpy.data.batch_remove(bpy.data.objects)

    with bpy.data.libraries.load(filepath = filepath) as (data_from, data_to):
        data_to.objects = data_from.objects

    for object in bpy.data.objects:
        print(object.matrix_world)


blender_exe = r'C:\blender\blender-4.2.0-alpha+main.196cd48aad53-windows.amd64-release\blender.exe'
filepath = r'D:\Desktop\city_hangar_test.blend'

command = [blender_exe, '-b', '--factory-startup', '-noaudio', '--python-expr', get_python_expr(import_model, filepath)]
subprocess.run(command, check = True, text = True)

command = ['blender', '-b', '--factory-startup', '-noaudio', '--python-expr', get_python_expr(import_model, filepath)]
subprocess.run(command, check = True, text = True)

Blender 4.2.0 Alpha (hash 196cd48aad53 built 2024-03-09 02:04:44)
<Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)>
<Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)>
<Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)>
<Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)
            (0.0000, 0.0000, 0.0000, 0.0000)>

Blender quit
Blender 3.1.2 (hash cc66d1020c3b built 2022-03-31 23:39:57)
<Matrix 4x4 (1.2342, 0.0000, 0.0000,  0.0325)
            (0.0000, 1.2342, 0.0000, -0.2509)
            (0.0000, 0.0000, 1.2342, -0.0213)
            (0.0000, 0.0000, 0.0000,  1.0000)>
<Matrix 4x4 (1.2342, 0.0000, 0.0000,  0.0325)
            (0.0000, 1.2342, 0.0000, -0.2509)
            (0.0000, 0.0000, 1.2342, -0.0213)
            (0.0000, 0.0000, 0.0000,  1.0000)>
<Matrix 4x4 (0.1274, 0.0000, 0.0000, -1.2274)
            (0.0000, 0.1274, 0.0000,  0.2705)
            (0.0000, 0.0000, 0.1274,  1.1341)
            (0.0000, 0.0000, 0.0000,  1.0000)>
<Matrix 4x4 (3.5520, 0.0000, 0.0000, -0.0264)
            (0.0000, 3.5520, 0.0000, -0.0000)
            (0.0000, 0.0000, 3.5520,  0.0132)
            (0.0000, 0.0000, 0.0000,  1.0000)>

Blender quit
```python import subprocess def get_python_expr(func, *args, **kwargs): """ Does not work with `shell=True`. """ import inspect import textwrap import json expr = [textwrap.dedent(inspect.getsource(func))] args_json = repr(json.dumps(args)) kwargs_json = repr(json.dumps(kwargs)) expr.append('import json') expr.append(f'args = json.loads({args_json})') expr.append(f'kwargs = json.loads({kwargs_json})') expr.append(f'{func.__name__}(*args, **kwargs)') return '\n'.join(expr) def import_model(filepath): import bpy bpy.data.batch_remove(bpy.data.objects) with bpy.data.libraries.load(filepath = filepath) as (data_from, data_to): data_to.objects = data_from.objects for object in bpy.data.objects: print(object.matrix_world) blender_exe = r'C:\blender\blender-4.2.0-alpha+main.196cd48aad53-windows.amd64-release\blender.exe' filepath = r'D:\Desktop\city_hangar_test.blend' command = [blender_exe, '-b', '--factory-startup', '-noaudio', '--python-expr', get_python_expr(import_model, filepath)] subprocess.run(command, check = True, text = True) command = ['blender', '-b', '--factory-startup', '-noaudio', '--python-expr', get_python_expr(import_model, filepath)] subprocess.run(command, check = True, text = True) ``` ```cmd Blender 4.2.0 Alpha (hash 196cd48aad53 built 2024-03-09 02:04:44) <Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000)> <Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000)> <Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000)> <Matrix 4x4 (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000) (0.0000, 0.0000, 0.0000, 0.0000)> Blender quit Blender 3.1.2 (hash cc66d1020c3b built 2022-03-31 23:39:57) <Matrix 4x4 (1.2342, 0.0000, 0.0000, 0.0325) (0.0000, 1.2342, 0.0000, -0.2509) (0.0000, 0.0000, 1.2342, -0.0213) (0.0000, 0.0000, 0.0000, 1.0000)> <Matrix 4x4 (1.2342, 0.0000, 0.0000, 0.0325) (0.0000, 1.2342, 0.0000, -0.2509) (0.0000, 0.0000, 1.2342, -0.0213) (0.0000, 0.0000, 0.0000, 1.0000)> <Matrix 4x4 (0.1274, 0.0000, 0.0000, -1.2274) (0.0000, 0.1274, 0.0000, 0.2705) (0.0000, 0.0000, 0.1274, 1.1341) (0.0000, 0.0000, 0.0000, 1.0000)> <Matrix 4x4 (3.5520, 0.0000, 0.0000, -0.0264) (0.0000, 3.5520, 0.0000, -0.0000) (0.0000, 0.0000, 3.5520, 0.0132) (0.0000, 0.0000, 0.0000, 1.0000)> Blender quit ```
Lleu Yang commented 2024-03-10 16:51:53 +01:00
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I can confirm that git bisect shows that 1c0f374ec3 is the first bad commit.

I can confirm that git bisect shows that 1c0f374ec3e3 is the first bad commit.
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Iliya Katushenock added
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Vitalii-2 commented 2024-03-10 18:34:40 +01:00
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I can confirm that git bisect shows that 1c0f374ec3 is the first bad commit.

so what I understood from commit's description is that blender no longer updates object matrices outside of depsgraph updates, requiring script writers linking object into any scene and forcing an update (which is rather heavy handed) or calculating valid matrix manually, which can very complicated if it's a linked object with constraints

> I can confirm that git bisect shows that 1c0f374ec3e3 is the first bad commit. so what I understood from commit's description is that blender no longer updates object matrices outside of depsgraph updates, requiring script writers linking object into any scene and forcing an update (which is rather heavy handed) or calculating valid matrix manually, which can very complicated if it's a linked object with constraints
Brecht Van Lommel commented 2024-03-11 14:10:03 +01:00
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CC @HooglyBoogly, this looks like a release blocker.

@lichtwerk @mod_moder I don't know if it's a formal policy, but for a high priority bug I think it's important to always CC the relevant developer, especially this close to the release.

CC @HooglyBoogly, this looks like a release blocker. @lichtwerk @mod_moder I don't know if it's a formal policy, but for a high priority bug I think it's important to always CC the relevant developer, especially this close to the release.
Hans Goudey self-assigned this 2024-03-11 14:11:38 +01:00
Philipp Oeser commented 2024-03-11 14:43:42 +01:00
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@brecht @mod_moder : we do have it in the https://developer.blender.org/docs/handbook/bug_reports/triaging_playbook/ (under "Advanced Actions")

Contact the commit author and/or subscribe the author in the issue to raise awareness.

If the issue was nailed down to a recent faulty commit, contact the commit author and/or subscribe the author in the issue to raise awareness

@brecht @mod_moder : we do have it in the https://developer.blender.org/docs/handbook/bug_reports/triaging_playbook/ (under "Advanced Actions") >Contact the commit author and/or subscribe the author in the issue to raise awareness. >If the issue was nailed down to a recent faulty commit, contact the commit author and/or subscribe the author in the issue to raise awareness
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Hans Goudey commented 2024-03-11 20:24:31 +01:00
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CC @HooglyBoogly, this looks like a release blocker.

To be clear, this is only a problem in main, not the 4.1 release branch.

>CC @HooglyBoogly, this looks like a release blocker. To be clear, this is only a problem in main, not the 4.1 release branch.
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Vitalii-2 commented 2024-03-11 21:06:41 +01:00
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while that does address issue for new objects. it doesn't address issue of objects loaded from blend files via python to have default matrices prior update (reported by first comment), which shares the root cause. or would that require separate issue?

while that does address issue for new objects. it doesn't address issue of objects loaded from blend files via python to have default matrices prior update (reported by first comment), which shares the root cause. or would that require separate issue?
Hans Goudey commented 2024-03-11 21:17:11 +01:00
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Seems like that should be a separate report. Indeed, when appending objects, the transforms won't be calculated until there's a depsgraph update.

Seems like that should be a separate report. Indeed, when appending objects, the transforms won't be calculated until there's a depsgraph update.
Sebastian Sille commented 2024-03-13 11:59:18 +01:00
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@HooglyBoogly This may have caused this error (pic below), I fixed it in 39f3ea4ab0

@HooglyBoogly This may have caused this error (pic below), I fixed it in https://projects.blender.org/blender/blender-addons/commit/39f3ea4ab0c18c85b8643d3be32161a2654e1fbd
blender bug.png
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blender bug.png
Vitalii-2 commented 2024-03-13 14:29:52 +01:00
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@HooglyBoogly This may have caused this error (pic below), I fixed it in 39f3ea4ab0

c0f374ec3e3 made blender not to calculate world and local matrices before depsgraph update (which was all 0, before commit that resolved this issue), so I'm fairly certain that it's the case.

but I can't help but wonder as to why import script doesn't read whole world space matrix from fbx and doesn't update matrix_world which would force blender to recalculate matrix_local?

> @HooglyBoogly This may have caused this error (pic below), I fixed it in https://projects.blender.org/blender/blender-addons/commit/39f3ea4ab0c18c85b8643d3be32161a2654e1fbd [c0f374ec3e3](https://projects.blender.org/blender/blender/commit/1c0f374ec3e3) made blender not to calculate world and local matrices before depsgraph update (which was all 0, before commit that resolved this issue), so I'm fairly certain that it's the case. but I can't help but wonder as to why import script doesn't read whole world space matrix from fbx and doesn't update `matrix_world` which would force blender to recalculate `matrix_local`?
Hans Goudey commented 2024-04-04 19:49:32 +02:00
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In Blender these matrices are calculated dynamically based on the original location, rotation, and scale, and various procedural effects like constraints, drivers, and the animation system. They aren't directly write-able.

In Blender these matrices are calculated dynamically based on the original location, rotation, and scale, and various procedural effects like constraints, drivers, and the animation system. They aren't directly write-able.
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Reference: blender/blender#119250
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