Godot 4.3 does not include a built-in **automated texture atlas generator** for runtime use, but provides tools and workflows for manual atlas creation and optimization:

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### **Manual Atlas Creation**
1. **AtlasTexture Resource**  
   Use the `AtlasTexture` class to define sub-regions of a larger texture manually[1][4]. This involves:
   - Setting the `atlas` property to the base texture
   - Defining the `region` (coordinates and size) for each sub-texture
   - Adjusting `margin` and `filter_clip` to prevent bleeding[4]

2. **TileSetAtlasSource**  
   For tilemaps, use `TileSetAtlasSource` to define grid-based atlases:
   - Configure `texture`, `margins`, and `separation` properties[3]
   - Expose tiles via `create_tile()` with grid coordinates[3]

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### **Runtime Atlas Generation**
To dynamically pack textures at runtime:
1. Use `Image` class to create a blank texture
2. Copy pixels from individual textures using `get_pixel()`/`set_pixel()` with calculated offsets[5]
3. Convert the final `Image` to a `Texture2D` for rendering

```gdscript
# Example pseudocode for runtime atlas generation
var atlas_image = Image.create(atlas_width, atlas_height, false, Image.FORMAT_RGBA8)
for texture in textures:
    var img = texture.get_image()
    atlas_image.blit_rect(img, img.get_used_rect(), offset)
var atlas_texture = ImageTexture.create_from_image(atlas_image)
```

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### **Editor Workflow**
1. **Static Atlas Preparation**  
   Use external tools (TexturePacker, Kenney NL) to create pre-packed atlases, then import them as `Texture2D` resources.

2. **Texture Atlas Importer**  
   Godot's `ResourceImporterTextureAtlas` can split a single texture into multiple `AtlasTexture` resources during import[6], but requires manually created source images.

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### **Performance Considerations**
While texture atlases reduce draw calls, modern hardware often minimizes their impact[2]. Prioritize optimization in areas like:
- 2D lighting
- Particle systems
- Overdraw from transparent textures[2]

For most use cases, manually prepared atlases combined with `AtlasTexture` or `TileSetAtlasSource` provide sufficient optimization without runtime generation[1][3][6].

Citations:
[1] https://docs.godotengine.org/de/stable/classes/class_atlastexture.html
[2] https://www.reddit.com/r/godot/comments/1215i6i/does_godot_automatically_make_texture_atlases/
[3] https://docs.godotengine.org/en/4.3/classes/class_tilesetatlassource.html
[4] https://docs.godotengine.org/en/4.3/classes/class_atlastexture.html
[5] https://forum.godotengine.org/t/how-to-generate-a-texture-atlas-from-multiple-images/64985
[6] https://docs.godotengine.org/en/4.3/classes/class_resourceimportertextureatlas.html
[7] https://github.com/godotengine/godot/issues/92671
[8] https://www.youtube.com/watch?v=oEBUXW674dc

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Answer from Perplexity: https://www.perplexity.ai/search/godot-4-3-texture-atlas-genera-40o0HDS7TciDehf23JYCew?utm_source=copy_output