fix: json algebra reading

[asalzburger]

Change the order of translation / rotation when reading transforms back from json.

This is necessary that the transforms are correctly re-created.

[codecov]

Codecov Report

Merging #1081 (33039ac) into main (f65cf50) will not change coverage.
The diff coverage is n/a.

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  Coverage   48.64%   48.64%           
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  Files         341      341           
  Lines       17489    17489           
  Branches     8256     8256           
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  Hits         8507     8507           
  Misses       3208     3208           
  Partials     5774     5774           

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[Corentin-Allaire]

Looks good ! Is the reason for this that Eigen Affine transform apply the translation first followed by the rotation ?

[paulgessinger]

I don't think Eigen Affine transforms to anything special here. I think this is related to the code changed here using prerotate and pretranslate rather than simple matrix multiplications.

[Corentin-Allaire]

I am not sure I follow your point here, A.pretranslate(B) is just BxA no ? Instead of AxB for translate.

[paulgessinger]

Exactly. But Eigen does not apply translation and rotation separately I don't think.

[Corentin-Allaire]

I probably didn't express myself properly. What I meant is that the Transform3 type we use is equal to Translation x Rotation x Scaling. So if you want to build it with translate and rotate, translate need to go first; but if you want to use pretranslate and prerotate, prerotate need to go first. I think we agree and at that point it is just miscommunication :)