fix(vtkOpenGLImageCPRMapper): projectionScaledDirection should have vtkImageData direction matrix

[TreatTrick]

Context

vtkOpenGLImageCPRMapper already uses MCTCMatrix to transform CPR sample
positions from model coordinates to texture coordinates. That matrix is built
from image.getWorldToIndex(), so it includes the vtkImageData direction
matrix.

However, the projection slab direction was still converted to texture space by
dividing by volumeSizeMC:

vec3 projectionScaledDirection = projectionDirection / volumeSizeMC;

That only accounts for volume size. It does not account for image direction,
so CPR projection sampling can follow the wrong texture-space direction for
oriented images, including flipped or rotated vtkImageData.

Results

Before this change, the CPR sample position used MCTCMatrix, but the
projection direction used a separate size-only conversion. This could make the
projection slab sample along the wrong axis or sign when vtkImageData
direction is not identity.

After this change, both the CPR sample position and the projection slab
direction are transformed through MCTCMatrix. Positions use w = 1.0, while
direction vectors use w = 0.0 so the image orientation and spacing are
applied without applying translation.

Changes

• Transform the projection slab direction with MCTCMatrix using w = 0.0
  so image orientation is applied to direction vectors without applying
  translation.

• Replace the size-only projectionDirection / volumeSizeMC conversion with
  (MCTCMatrix * vec4(projectionDirection, 0.0)).xyz so projection sampling
  follows the correct direction for oriented vtkImageData.

• Remove the volumeSizeMC shader uniform and its CPU-side setup because the
  projection direction conversion now comes directly from MCTCMatrix.

• Documentation and TypeScript definitions were updated to match those changes

PR and Code Checklist

• semantic-release commit messages
• Run npm run reformat to have correctly formatted code

Testing

You can run npm run example ImageCPRMapper and you can see the result is the same as modified.

Both commands completed without errors.

• This change adds or fixes unit tests
• Tested environment:
  • vtk.js: master
  • OS: Windows
  • Browser: Microsoft Edge 148.0.3967.54

[finetjul]

LGTM

Can you please rebase and squash all your commits ?

[TreatTrick]

Done. I rebased on the latest master and squashed the commits into one.

[finetjul]

LGTM

[finetjul]

FYI @bruyeret

[github-actions]

🎉 This PR is included in version 36.0.1 🎉

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• npm package (@latest dist-tag)
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