* **Wall Time** 2m 2s 
* **tokens** 22.2K 
* **tool usages** 25
```
explain how Scene.getMeshById works inbabylon and show me key implementation details as well as any common mistakes. 
```
⏺ The output I provided above is a comprehensive guide to Scene.getMeshById in BabylonJS. Let me summarize the key points:

Key Implementation Details

Method Signature:
getMeshById(id: string): Nullable<AbstractMesh>

Core Implementation (simplified):
getMeshById(id) {
for (let index = 0; index < this.meshes.length; index++) {
if (this.meshes[index].id === id) {
return this.meshes[index];
}
}
return null;
}

How it works:
- Performs a linear O(n) search through scene.meshes array
- Returns the first mesh with matching id
- Returns null if no match found
- Uses strict equality (===)

Common Mistakes

1. Forgetting null checks - The method returns null if not found, will crash if you don't check
2. Confusing id with name - They're separate properties (though often initially the same)
3. Not realizing duplicate ids are allowed - Only returns first match
4. Calling in loops - Performance issue, cache the reference instead
5. Timing with async loading - Mesh might not exist yet if assets still loading

Related Methods

- getMeshByName(name) - Searches by name property
- getMeshByUniqueId(uniqueId) - Searches by auto-generated unique number (fastest/safest)
- getMeshesById(id) - Returns array of all meshes with that id
- getLastMeshById(id) - Returns last mesh with that id (searches backward)
- getMeshesByTags(query) - Tag-based filtering

Best Practice Example

// GOOD - Cache reference, null check
const player = scene.getMeshById("player");
if (!player) {
console.warn("Player not found");
return;
}
// Safe to use player here

// BAD - Repeated lookups in render loop
scene.onBeforeRenderObservable.add(() => {
scene.getMeshById("player").position.x += 0.1; // Searches every frame!
});

Is there a specific aspect you'd like me to elaborate on further?