fix(labelmap) : Display labelmap on volume3d viewport

[Celian-abd]

Context

The labelmap was showing on mip using volume or orthographic viewport but it was not working for volume3d.

Changes & Results

• Moved getBlendMode() method in BaseVolumeViewport instead of VolumeViewport
• Changed the VolumeViewport check to BaseVolumeViewport

This changes allow the labelmap to render on volume3d viewport aswell as volume.

Testing

Can be tested in the labelmapMIP example.

Checklist

PR

• [] My Pull Request title is descriptive, accurate and follows the
  semantic-release format and guidelines.

Code

• [] My code has been well-documented (function documentation, inline comments,
  etc.)

Public Documentation Updates

• [] The documentation page has been updated as necessary for any public API
  additions or removals.

Tested Environment

• [] "OS:
• [] "Node version:
• [] "Browser:

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[sedghi]

The issue is what happens on the real 3D viewport, since we don't want to render Labelmap in 3D viewport, the best representation for segmentation in 3D viewport is actually a surface

[salimkanoun]

But actually it works pretty well even in 3D viewport, maybe @Celian-abd you can make a video of the cornerstone example with 3D viewport with labelmap?

[sedghi]

yes please, let's see. Create couple of segments that overlap if camera looks at them from different angles

[salimkanoun]

Hum overlap I'm not sure, however not la elmap have overlap, it can be a known limitation of this rendering that fit several use cases

[Celian-abd]

3D viewport with labelmap

[sedghi]

but is that a 3d viewport or a mip viewport?

[Celian-abd]

It's a volume3D viewport

 {
      viewportId: viewportId2,
      type: ViewportType.VOLUME_3D,
      element: element2,
      defaultOptions: {
        orientation: Enums.OrientationAxis.SAGITTAL,
        background: <Types.Point3>[0.2, 0, 0.2],
      },
    },

[sedghi]

can you pull main, i fixed the tests

[sedghi]

This requires a lot more testing from me, it will take some time sorry