refactor: do not premultiply point sizes, improve point discarding

[jwindhager]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (5976c9e) to head (e249f10).
⚠️ Report is 13 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##            main       #51       +/-   ##
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+ Coverage   4.41%   100.00%   +95.58%     
===========================================
  Files         77         5       -72     
  Lines       4324        71     -4253     
  Branches     112        17       -95     
===========================================
- Hits         191        71      -120     
+ Misses      4098         0     -4098     
+ Partials      35         0       -35     

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unittests	100.00% <ø> (+95.58%)	⬆️

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[Copilot]

Pull request overview

This PR refactors the point rendering system to avoid premultiplying point sizes on the CPU, moving size calculations to the GPU shader instead. This improves the separation of concerns and allows the shader to handle size transformations more accurately.

Changes:

• Removed sizeFactor parameter from LoadUtils.loadSizeData() to store raw size values without premultiplication
• Added new uniforms to the shader for viewport size, canvas size, and device pixel ratio to enable proper size calculations
• Modified the WebGL controller to pass size factors separately in a uniform buffer object instead of premultiplying them into size data

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 7 comments.

File	Description
packages/@tissuumaps-core/src/utils/LoadUtils.ts	Removed sizeFactor parameter and all premultiplication logic from size data loading
packages/@tissuumaps-core/src/controllers/WebGLPointsController.ts	Added new uniform locations, modified buffer layout to store size factors separately, updated state tracking
packages/@tissuumaps-core/src/assets/shaders/points.vert	Added new uniforms, implemented size calculations in shader, improved point discarding logic with viewport culling

Comments suppressed due to low confidence (1)

packages/@tissuumaps-core/src/controllers/WebGLPointsController.ts:629

• Incorrect buffer target for loading uniform buffer data. The code is using this._gl.ARRAY_BUFFER as the target when loading data into this._buffers.objectsUBO, but this buffer should be bound as this._gl.UNIFORM_BUFFER since it's a uniform buffer object (UBO). While WebGL may be lenient about this, it's semantically incorrect and could lead to issues or confusion.

    WebGLUtils.loadBuffer(
      this._gl,
      this._gl.ARRAY_BUFFER,
      this._buffers.objectsUBO,

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