# General

## Hatch

```
hatch config set dirs.env.virtual .direnv
```

## How to renew certificates

Run `certbot renew --cert-name data.virtualbrainlab.org` on the data server.

Copy the certificate and privkey files from `C:\Certbot\live\data.virtualbrainlab.org` to `C:\Apache24\conf\ssl`. The certificate should be named `server` and the private key `server.key`.

Restart `Services > Apache2 > Restart`

Confirm that the key propagated correctly.

## Unity tips

**Tutorials**

Brackeys has a great high quality introductory sequence: [start here](https://www.youtube.com/watch?v=j48LtUkZRjU&list=PLPV2KyIb3jR5QFsefuO2RlAgWEz6EvVi6)

[Imphenzia](https://www.youtube.com/watch?v=pwZpJzpE2lQ) also has a great and slightly more up-to date introduction.

### Version and packages

The majority of our code relies only on the base Unity environment. We are currently (2023-07) on Unity Editor version 2022.3.4f1 LTS.

Below are a list of all the major packages we use with a short explanation for their use.

### Neurons (DOTS/ECS)

To display large numbers of neurons we rely on the entities and components system (ECS) from DOTS. This codebase organizes memory in a more efficient layout which allows us to render and update hundreds of thousands of scene objects on each frame.

**Tutorials**: [Turbo Makes Games](https://www.youtube.com/c/TurboMakesGames) probably has the best tutorials for DOTS/ECS. 

### Large asset streaming (Addressables)

Whenever we have to store and load large files we rely on Unity's impressive Addressables asset bundle system. They use state-of-the-art compression and streaming which seriously reduces the overhead for us when using very large files. 

Addressable assets are an excellent way to reduce memory overhead in builds, but they come at the cost of increased complexity and the requirement to write code with asynchronous function calls.

**Tutorials**: Bit out of date but this one by [Jason Weimann](https://www.youtube.com/watch?v=uNpBS0LPhaU) is good.

**Warning:** Addressables rely on the Unity version matching in the Addressables build and the Unity build, if you make any changes you must update the builds and change them on the asset server.

### Rotations

https://eater.net/quaternions

### WebGL limitations

When developing new Unity tools you should be very careful about introducing new memory requirements or heavy GPU usage. WebGL has a frame rate limitation of about 60hz on most computers and a memory limitation of 2GB.

### Troubleshooting

If you see **null reference exceptions** when referring to editor-linked objects (either serialized or public) it's possible that you linked the *asset* and not the object in the scene.