Documentation pages to add or update for Godot 4

**Note:** This issue is only for manual pages. For class reference pages, refer to the automatically updated tracker: https://godotengine.github.io/doc-status/

Help for working on these pages is welcome. If you're going to start writing a new page or rewrite an existing one, please leave a comment to state which page you're going to work on :slightly_smiling_face:

## New pages

Pages to write for features that were not present in Godot 3.x.

- [x] Large world coordinates (double-precision physics) https://github.com/godotengine/godot-docs/pull/6314
- [x] 3D resolution scaling (FSR) https://github.com/godotengine/godot-docs/pull/6331
- [x] 3D antialiasing https://github.com/godotengine/godot-docs/pull/6267
- MSAA, TAA, FXAA, supersampling (resolution scale above 1.0).
- [x] 2D antialiasing https://github.com/godotengine/godot-docs/pull/6267
- MSAA – mention what it affects and what it doesn't in 2D.
- [x] Variable rate shading (VRS) https://github.com/godotengine/godot-docs/pull/6402
- [x] 3D particle systems https://github.com/godotengine/godot-docs/pull/5535
- We don't have a page dedicated to 3D particles yet. This page should mention how to set up attractors, collision and trails. Setting up manual emission in a shader should be done in a dedicated page about particle shaders, since it's an advanced feature.
- [x] Volumetric fog https://github.com/godotengine/godot-docs/pull/6162
- [x] Mesh LOD https://github.com/godotengine/godot-docs/pull/6161
- [x] Visibility ranges https://github.com/godotengine/godot-docs/pull/6161
- [x] Occlusion culling https://github.com/godotengine/godot-docs/pull/6160
- Using the raster-based approach, different from portals and rooms in `3.x`.
- [x] Introduction to global illumination https://github.com/godotengine/godot-docs/pull/6216
- Mention faking outdoor GI with a second DirectionalLight as an alternative to Godot's GI methods: https://github.com/godotengine/godot-proposals/issues/3353#issuecomment-930413969
- Faking indoor GI with OmniLights or SpotLights is also an option. It's still done in many AAA games today, but it involves a lot more manual work. It's still viable for dynamic lights when your GI solution of choice does not support real-time GI of moving lights (such as LightmapGI or SDFGI).
- [x] Signed distance field global illumination https://github.com/godotengine/godot-docs/pull/6216
- Tweaking performance figures, avoiding light leaks, etc.
- [x] Decals https://github.com/godotengine/godot-docs/pull/6178
- See https://youtu.be/CrOI5HUAPCg?t=9760 for inspiration.
- [x] GDExtension https://github.com/godotengine/godot-docs/pull/6212
- See https://godotengine.org/article/introducing-gd-extensions for inspiration.
- [x] Upgrading to Godot 4 https://github.com/godotengine/godot-docs/pull/6393
- See https://github.com/godotengine/godot-docs/issues/4960.
- [x] Global and per-instance shader uniforms https://github.com/godotengine/godot-docs/pull/6414
- Also document how to support specifying textures in per-instance uniforms. For portability reasons, you can't actually use textures in instance uniforms, but you can specify a texture array as a standard uniform and specify the *layer* to sample from as a instance uniform integer.
- [x] Using compute shaders https://github.com/godotengine/godot-docs/pull/6159
- Documentation about writing and running compute shaders using local RenderingDevices. See also https://github.com/godotengine/godot-docs/issues/4834.
- [x] Using low-level GLSL shaders https://github.com/godotengine/godot-docs/pull/6159
- Documentation about loading custom GLSL shaders (advanced users only).
- See the end of https://godotengine.org/article/vulkan-progress-report-7 for inspiration.
- [x] Custom performance monitors https://github.com/godotengine/godot-docs/pull/6409
- Documentation about creating and viewing the output of [custom performance monitors](https://github.com/godotengine/godot/pull/39302).
- [x] Animation retargeting https://github.com/godotengine/godot-docs/pull/6322
- See https://godotengine.org/article/animation-retargeting-in-godot-4-0 for inspiration.
- [x] Physical light units https://github.com/godotengine/godot-docs/pull/6390
- Documentation about enabling, meaning of various units, pitfalls to watch out for.
- [x] Run-time model loading https://github.com/godotengine/godot-docs/pull/8363
- See https://github.com/godotengine/godot-docs/issues/6385.
- [ ] CanvasItem clipping (masking) and grouping
- 2D lights and shadows page should refer to this page in place of the former Mask blend mode.

## Pages to rewrite

These pages need rewrites from scratch with new screenshots.

- [x] Engine's compilation guides at https://docs.godotengine.org/en/latest/development/compiling/index.html needs to be updated after the merge of https://github.com/godotengine/godot/pull/66242. https://github.com/godotengine/godot-docs/pull/6316 https://github.com/godotengine/godot-docs/pull/6375
- [x] Environment and post-processing https://github.com/godotengine/godot-docs/pull/6273
- [x] Using Fonts https://github.com/godotengine/godot-docs/pull/6373
- Mention font fallbacks, variable fonts, OpenType variants, subpixel positioning and LCD subpixel optimization. Also mention that ligatures and emoji are fully supported since 4.0.
- [x] Import process https://github.com/godotengine/godot-docs/pull/6782
- [x] Importing images https://github.com/godotengine/godot-docs/pull/6782
- [x] Importing audio samples https://github.com/godotengine/godot-docs/pull/6782
- [x] Importing 3D scenes https://github.com/godotengine/godot-docs/pull/6603 + https://github.com/godotengine/godot-docs/pull/6800
- [ ] Size and anchors (UI)
- See https://github.com/godotengine/godot-docs/issues/11071.
- [x] 2D tilemaps and tilesets https://github.com/godotengine/godot-docs/pull/6760
- [ ] 2D skeletal animation
- See https://github.com/godotengine/godot-docs/issues/6388.
- [x] 2D lights and shadows https://github.com/godotengine/godot-docs/pull/6424
- Mention directional 2D lights, specular mapping and the new shadow smoothing options (different from the ones in 3.x).
- [x] 3D lights and shadows https://github.com/godotengine/godot-docs/pull/6355
- Mention the soft shadow properties.
- Document setting up projectors for both spot and omni lights (omni lights require panorama textures).
- Mention performance tuning and project settings.
- [ ] Kinematic Character (2D)
- [ ] 2D particle systems
- Mention how to set up attractors, collision and trails. Setting up manual emission in a shader should be done in a dedicated page about particle shaders, since it's an advanced feature.
- [x] Voxel GI (replaces the old GI Probes page) https://github.com/godotengine/godot-docs/pull/6216
- [x] Baked lightmaps (mention the GPU lightmapper and LightmapGI node) https://github.com/godotengine/godot-docs/pull/6216
- [x] High-level multiplayer https://github.com/godotengine/godot-docs/pull/7675
- See https://github.com/godotengine/godot-docs/issues/6741.
- See https://godotengine.org/article/multiplayer-changes-godot-4-0-report-2 for inspiration.
- [x] Internationalizing games https://github.com/godotengine/godot-docs/pull/6418
- Mention translation contexts and pluralization.