Prepare multi modality support

[philippotto]

Summary

• Supports rendering a dataset where layers can be transformed each (with an affine matrix).
• Transformation can be specified via datasource-properties.json or via JS API (will be ephemeral, then)
• Rendering was re-architectured to use cuckoo hashing for the dynamic look up of bucket addresses.
• Progressive rendering is done on the GPU (instead of on the CPU).
• For performance reasons, the plane geometries are now tessellated and the vertices are mutated by the vertex shader so that they are bucket-aligned. This enables us to precompute the cuckoo lookup in the vertex shader.
• The pre-computation is disabled when interpolation is enabled (would cause problems at chunk borders, otherwise). Also as a workaround for issues at chunk borders, pre-computation is ignored there, too (independent of interpolation).
• Transformed layers won't be rendered using the above optimization (since their buckets won't align with the vertices).
• Since enabling interpolation can incur a performance cost, it's disabled by default (won't affect old preferences) and the user will get a small hint in the left sidebar if it's enabled.
• As a consequence of the individually transformed layers, it can happen that one layer is rendered in a different magnification than another layer. This used to be uniform, but isn't anymore now (even though, it should still be uniform when no transformations are used).

URL of deployed dev instance (used for testing):

• https://multimodality.webknossos.xyz

To do:

• allow to define transforms per layer which are used in the shader
• adapt bucket picking to respect layer transformations
• allow to make the active mag dependent on each layer (one layer can be rendered in mag 1 and the other in mag 4)
• remove anchor point mechanism in favor of hashing to address buckets on the GPU
• Backend: Store matrix from datasource-properties.json in postgres, include in dataset json sent to frontend
• Restore old behavior/functionality:
  • progressive rendering
  • data that is still being loaded should be gray instead of black
  • "The currently rendered quality is not optimal due to the available magnifications and the viewport arrangement." shows false positively
  • find my data needs to be adapted.
• Fix bugs:
  • having more layers in a DS than can be rendered at the same time results in rendering issues
  • rotation from arbitrary mode is not removed when switching back to orthogonal mode
  • deep freeze breaks for transform matrices apparently
  • thin lines at bucket borders (solved by disabling anti aliasing which prevents flat varyings to be interpolated errorenously)
  • data offset by 32vx
  • missing data at border
  • weird triangles at border
  • sometimes bucket strip shows at viewport boundary shows wrong data
  • some transformations cause incorrect data to be rendered (needs investigation)
  • XZ and YZ rendering is corrupt (probably the computation in the vertex shader is not adapted yet)
  • sometimes cross hairs are invisible (probably due to disabled antialiasing)
  • support segmentation layers again
  • fix line artifact when rendering segmentation layer (this is caused by the segmentation patterns which rely on partial derivatives; unfortunately, these seem to be buggy now that there's a special tessellation)
• Performance (solved by performing bucket look up in vertex shader)
• clean up UI
  • display correct mag etc
  • fix CI tests
  • fix screenshot tests
  • add warning for performance for interpolation?
  • disable performance optimization when interpolation is enabled
  • change default for interpolation
  • doublecheck bucket loading order for transformed layers
• go through to do comments in code

Steps to test:

• test view mode and annotation mode for multiple datasets
• pay attention to performance and rendering issues

Issues:

• fixes Support multi-modality datasets #6085

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(Please delete unneeded items, merge only when none are left open)

• Updated (unreleased) changelog
• Updated (unreleased) migration guide if applicable
• Updated documentation if applicable
• Adapted wk-connect if datastore API changes
• Adapted wk-libs python client if relevant API parts change
• Needs datastore update after deployment
• Ready for review

[philippotto]

@daniel-wer I incorporated your remaining feedback and also updated the screenshots. I'll add an additional screenshot test for the transformations in a follow-up PR. If you accept the PR, I'll merge it today :)

[daniel-wer]

LGTM 🎉