WIP: Fix #119404: USD import: Incorrect translation for scaled bones #120328

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Michael Kowalski wants to merge 5 commits from makowalski/blender:usd-skel-import-noisy-translations into main

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NOTE: This pull request is not yet ready for review.

This addresses an issue observed in #119404.

Non-unit scales in skeleton bind matrices can cause incorrect
translation values in the bone animation, because when computing
the translation components scaling is ignored.

This commit adds the code to apply the bind matrix scaling to
the translation.

Also added a call to normalize the bind transform when creating the
bones, to avoid an assertion failure in ED_armature_ebone_from_mat4()
when the transform has a non-unit scale.

Testing

There are two test cases:

  1. Load the attached skeleton_with_schema.usda. Without the fix, very subtle changes in bone translations cause big jumps in the animation.
  2. The attached armScaledBones.usda file has a skeleton where the bones are scaled uniformly by .1. In addition, bone Shoulder/Elbow has a local Y translation that animates from 2 to 3. Without the fix, the distance between the first and second bones is too large at the end of the animation.
**NOTE: This pull request is not yet ready for review.** This addresses an issue observed in #119404. Non-unit scales in skeleton bind matrices can cause incorrect translation values in the bone animation, because when computing the translation components scaling is ignored. This commit adds the code to apply the bind matrix scaling to the translation. Also added a call to normalize the bind transform when creating the bones, to avoid an assertion failure in ED_armature_ebone_from_mat4() when the transform has a non-unit scale. ### Testing There are two test cases: 1. Load the attached `skeleton_with_schema.usda`. Without the fix, very subtle changes in bone translations cause big jumps in the animation. 2. The attached `armScaledBones.usda` file has a skeleton where the bones are scaled uniformly by .1. In addition, bone `Shoulder/Elbow` has a local Y translation that animates from 2 to 3. Without the fix, the distance between the first and second bones is too large at the end of the animation.
Michael Kowalski added the
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labels 2024-04-05 23:55:32 +02:00
Michael Kowalski added 2 commits 2024-04-05 23:55:42 +02:00
Normalizing the bind matrix.

Scaling bone translation curves by the bind
matrix scale.
Michael Kowalski added this to the USD project 2024-04-05 23:55:46 +02:00
Michael Kowalski changed title from WIP: USD import: Incorrect translation for scaled bones to WIP: Fix #119404: USD import: Incorrect translation for scaled bones 2024-04-06 00:30:09 +02:00
Michael Kowalski added 3 commits 2024-05-08 18:34:58 +02:00
This pull request is marked as a work in progress.

Checkout

From your project repository, check out a new branch and test the changes.
git fetch -u usd-skel-import-noisy-translations:makowalski-usd-skel-import-noisy-translations
git checkout makowalski-usd-skel-import-noisy-translations
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Reference: blender/blender#120328
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