A physics driven space flight simulation using Unity's new DOTS.
I want to make this usable as a library. The Assets/Scripts directory contains
everything. Other stuff in the repo are just samples and documents.
It is not supposed to directly edit anything in this package. One could derive sub-class if needed. Or use various delegates to tap into processes.
I also want to salvage my long forgotten maths & physics. So there are lots of grade school comments littering all over.
Open Assets/Scenes/Space/Startup.unity and play.
Current thought is to use one empty scene repeatedly and spawn everything on the fly.
EntityManager.MoveEntitiesFrom() doesn't move the whole hierarchy of prefabs.
Only the entities selected by EntityQuery will be moved, no child under them would
be moved. Because of this, off-active-world entity creation is almost (practically)
impossible.
However, such creation process happening on main thread is not too bad at the moment, unless creating many hundreds or more entities at once. Mostly the rendering pipeline will crumble if a few dozens entities were spawned in sight. Long before one would have to worry about entity creation.
The PhysicsStep component is not destroyed after a scene were unloaded. Say two
scene (A & B) both have an entity with PhysicsStep component on them. When you
switch from scene A to scene B using SceneManager.LoadScene("B"), the PhysicsStep
from scene A will persist into scene B. Resulting in broken physics simulation.
I count myself as a beginner. So I have a dedicated section here.
In Unity, moment of inertia is not a simple number. Instead, it is the inertia tensor
in Vector3 (Rigigbody.inertiaTensor) for GameObject, and float3 for ECS
Physics Shape.
In ECS, Physics Body, Physics Mass and Physics Shape replace the Rigidbody
component. And they have a bit more parameters can be tweaked than the GameObject's
Rigigbody counterpart. But do note that, such as Physics Mass, it's
inverseInertia, though the underlying numbers are the same.
The ConvertToEntity component is a heavy duty task. The
Crosair
game object from the Space-Flight-Unity takes around 3.5 seconds to convert
on-the-fly. Although the conversion is a one-time process happens at the first time
of instantiation. Working out a dozen game objects will freeze the game for quite a
while.
This is the reason to always stick to sub-scenes. Placing prefabs to sub-scene saves a whole lot of runtime resources. Even prefabs not requiring entity conversion will benefit greatly from the sub-scene cache.
- In 2019.3, the NetCode package has an error, so it is temporarily uninstalled.
Library\PackageCache\com.unity.netcode@0.0.4-preview.0\Runtime\ClientServerWorld\ClientServerBootstrap.cs(31,33):
error CS1503: Argument 1: cannot convert from 'System.Collections.Generic.IReadOnlyList<System.Type>' to 'System.Collections.Generic.List<System.Type>'