Add point-cloud and Gaussian splat support to Triptych360

[Copilot]

Triptych360 previously accepted only equirectangular images/videos. This change extends the app to load and render 3D point-based content from LAS/LAZ point clouds and Gaussian splat data (PLY/SPLAT), while preserving existing panorama/video behavior.

• Rendering path for 3D datasets

  • Added a point-rendering mode in PanoViewWidget with dedicated GLSL shaders.
  • Introduced per-point position/color/size buffers and camera-driven MVP transforms for interactive view control.
  • Kept existing pano texture pipeline intact and mode-switched at runtime.

• New model loaders

  • Added LAS/LAZ parsing via laspy (x/y/z, optional RGB).
  • Added Gaussian splat support from:
    • .ply vertex data (x/y/z, optional red/green/blue, f_dc_*, opacity, scale_*)
    • .splat binary records (position, scale, RGBA payload).
  • Normalized model coordinates to stable view space and mapped splat metadata to point size/alpha.

• UI + media workflow updates

  • Expanded file picker filters to include *.las *.laz *.ply *.splat.
  • Updated controller copy to “Load Media / 3D Model”.
  • Unified interaction gates (scene_loaded) so drag/zoom/idle-pan/SpaceMouse work for both media and 3D scenes.

• Dependencies + docs

  • Added laspy[lazrs] and plyfile to requirements.
  • Updated README to reflect 3D support, current UI labels, and supported format matrix.

path, _ = QFileDialog.getOpenFileName(
    self,
    "Open 360 Media / 3D Data",
    "",
    "Media & 3D (*.png *.jpg *.jpeg *.mp4 *.mkv *.avi *.mov *.las *.laz *.ply *.splat)"
)

if path_lower.endswith(('.las', '.laz')):
    points, colors, sizes = self._load_las_laz(path)
elif path_lower.endswith(('.ply', '.splat')):
    points, colors, sizes = self._load_gaussian_splats(path)

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.