Blender 3.5 returns identity instead of real value for matrix_basis, 3.4 works ok #106340

New Issue

TVP · 2023-03-30T21:47:32+02:00

TVP commented

2023-03-30 21:47:32 +02:00

System Information
Operating system: Linux 5.15.0-67-generic #74~20.04.1-Ubuntu SMP Wed Feb 22 14:52:34 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

Graphics card: 00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07)

Blender Version
Broken: 3.5.0, build hash: 1be25cfff1, build date: 2023-03-29
Worked: 3.4.1, build hash: 55485cb379, build date: 2022-12-20

Short description of error
Blender 3.5 returns identity instead of real value for matrix_basis, 3.4 works ok. Seems to happen only to certain bones controlled by IK

Exact steps for others to reproduce the error

run matrix_basis_test.sh, the output should be

Blender 3.4.1 (hash 55485cb379f7 built 2022-12-20 00:46:45)
Read prefs: /home/tv/.config/blender/3.4/config/userpref.blend
Reloading external rigs...
Reloading external metarigs...
Read blend: /tmp/matrix_basis_3.4.blend
pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=0
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9355, x=-0.3533, y=0.0000, z=0.0000)> frame=10
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9977, x=-0.0674, y=0.0000, z=0.0000)> frame=20
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9876, x=0.1572, y=0.0000, z=0.0000)> frame=30
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9705, x=-0.2410, y=0.0000, z=0.0000)> frame=40
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9355, x=-0.3533, y=0.0000, z=0.0000)> frame=50

Blender quit
Blender 3.5.0 (hash 1be25cfff18b built 2023-03-29 06:35:04)
Read prefs: /home/tv/.config/blender/3.5/config/userpref.blend
Reloading external rigs...
Reloading external metarigs...
Read blend: /tmp/matrix_basis_3.5.blend
pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=0
pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=10
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9977, x=-0.0674, y=0.0000, z=0.0000)> frame=20
pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=30
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9705, x=-0.2410, y=0.0000, z=0.0000)> frame=40
pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9355, x=-0.3533, y=0.0000, z=0.0000)> frame=50
Blender quit

notice difference for frame 30,
blender 3.5 prints Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)
blender 3.4 prints Quaternion (w=0.9876, x=0.1572, y=0.0000, z=0.0000)

**System Information** Operating system: Linux 5.15.0-67-generic #74~20.04.1-Ubuntu SMP Wed Feb 22 14:52:34 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux Graphics card: 00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07) **Blender Version** Broken: 3.5.0, build hash: 1be25cfff18b, build date: 2023-03-29 Worked: 3.4.1, build hash: 55485cb379f7, build date: 2022-12-20 **Short description of error** Blender 3.5 returns identity instead of real value for matrix_basis, 3.4 works ok. Seems to happen only to certain bones controlled by IK **Exact steps for others to reproduce the error** run matrix_basis_test.sh, the output should be ``` Blender 3.4.1 (hash 55485cb379f7 built 2022-12-20 00:46:45) Read prefs: /home/tv/.config/blender/3.4/config/userpref.blend Reloading external rigs... Reloading external metarigs... Read blend: /tmp/matrix_basis_3.4.blend pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=0 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9355, x=-0.3533, y=0.0000, z=0.0000)> frame=10 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9977, x=-0.0674, y=0.0000, z=0.0000)> frame=20 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9876, x=0.1572, y=0.0000, z=0.0000)> frame=30 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9705, x=-0.2410, y=0.0000, z=0.0000)> frame=40 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9355, x=-0.3533, y=0.0000, z=0.0000)> frame=50 Blender quit Blender 3.5.0 (hash 1be25cfff18b built 2023-03-29 06:35:04) Read prefs: /home/tv/.config/blender/3.5/config/userpref.blend Reloading external rigs... Reloading external metarigs... Read blend: /tmp/matrix_basis_3.5.blend pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=0 pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=10 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9977, x=-0.0674, y=0.0000, z=0.0000)> frame=20 pbone=thigh.L matrix_basis_q=<Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000)> frame=30 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9705, x=-0.2410, y=0.0000, z=0.0000)> frame=40 pbone=thigh.L matrix_basis_q=<Quaternion (w=0.9355, x=-0.3533, y=0.0000, z=0.0000)> frame=50 Blender quit ``` notice difference for frame 30, blender 3.5 prints Quaternion (w=1.0000, x=0.0000, y=0.0000, z=0.0000) blender 3.4 prints Quaternion (w=0.9876, x=0.1572, y=0.0000, z=0.0000)

matrix_basis.blend

1.8 MiB

matrix_basis_test.py

735 B

matrix_basis_test.sh

260 B

TVP added the

labels 2023-03-30 21:47:32 +02:00

Richard Antalik added

and removed

labels 2023-03-31 20:41:48 +02:00

Richard Antalik commented

2023-03-31 20:41:57 +02:00

Will bisect.

Richard Antalik commented

2023-04-02 21:27:24 +02:00

I wasn't able to bisect this. Release build of 9cb061f4f0 gives bad result, but debug build seems to be fine. I guess there is some thread race condition going on.

I wasn't able to bisect this. Release build of 9cb061f4f011 gives bad result, but debug build seems to be fine. I guess there is some thread race condition going on.

Nathan Vegdahl self-assigned this 2023-05-05 12:56:40 +02:00

Nathan Vegdahl commented

2023-05-05 14:46:58 +02:00

TLDR; turns out this is a duplicate of #106708, and has already been fixed in 85ed2e8c36

Longer explanation:

So, it turns out the actual underlying issue here is the same as the bug reported in #106708: when baking to actions that already have animation in them, the existing keys would (erroneously) remain, resulting in two keys on the same frame but with different values (one from the original action, and one from the bake). It looks like this:

So when you ask for matrix_basis on a frame like that, it might be computed from the old original key or the new baked key. And in the case of at least Blender 3.5, it would choose the first of the two keys, resulting in the reported identity matrix behavior.

The actual bug (the double keys, which isn't supposed to be allowed) was fixed in 85ed2e8c36 and will be in the next Blender release.

TLDR; turns out this is a duplicate of #106708, and has already been fixed in 85ed2e8c368bb624166d5082df79faa9d983573e Longer explanation: So, it turns out the actual underlying issue here is the same as the bug reported in #106708: when baking to actions that already have animation in them, the existing keys would (erroneously) remain, resulting in two keys on the same frame but with different values (one from the original action, and one from the bake). It looks like this: ![overlapping_keys.jpg](/attachments/8c66010c-8149-413e-b3f3-5571c0570867) So when you ask for `matrix_basis` on a frame like that, it might be computed from the old original key or the new baked key. And in the case of at least Blender 3.5, it would choose the first of the two keys, resulting in the reported identity matrix behavior. The actual bug (the double keys, which isn't supposed to be allowed) was fixed in 85ed2e8c368bb624166d5082df79faa9d983573e and will be in the next Blender release.

overlapping_keys.jpg

91 KiB

👍 1

Nathan Vegdahl closed this issue

2023-05-05 14:47:00 +02:00

Blender Bot added

and removed

labels 2023-05-05 14:47:06 +02:00