Suggestion / Idea ECS Physics/Graphics Support

[josemendez]

- GameObjects will get entities, this does not mean entities based project will need to have GameObjects afaik.

More like GameObjects will become entities under the hood, according to their description of how they plan to make it work internally.

- The update of e.g. ObiSolver Inertial Frame fetches transform.position and cause transform jobs to cause a sync point and wait, this _can_ be big performance sink if you run a lot of jobs.

Transforms will be unified between GameObjects and Entities and there will be no sync /data copying between them whatsoever. This is mentioned in the discussions thread I linked:

Transforms will also be evolving to reduce the considerable time spent to read/write/sync Transform data between GameObjects and Entities. Unified Transform will merge ECS and GameObjects Transforms so we no longer have to copy data between two different representations. [...]  You will also be able to manipulate the Transform of a GameObject directly via ECS APIs, fully Burst-able.

I understand the hesitation to do anything since it doesn't seem to be too _far_ away and a lot of things might be unecessary.

Using Unity's ECS system instead of our own would essentially require rewriting the entire asset from the ground up, which is probably not worth the effort given that Unity is planning for tighter integration of ECS and GameObject workflows in the near future.

But I have another issue I would want support with;
My case is to have a character on a platform, I think my end goal is would be to have 100% wind linear + angular velocity from movement and interta from local movement on platform,
and only have partial from platform the playform.

When I move things with ECS and interpolate it with physics, I get a lot of jittery impulses from world velocity and linear inertia. (I think also for rotation, but I'm not rotating that fast to make it noticible) My guess here is that it happens by inaccuracies in deltas + interpolation between physics and obi. I tested to set 0 inertia, sim space local, and apply delta movement as wind, and it had same issue.

How/when are you moving things relative to Obi's update? Could you give a bit more information about what you're doing and how?

Interpolation (as in physics state interpolation) doesn't affect physical behavior, it only affects visuals. The thing being interpolated is object positions/orientations resulting from two different physics steps, but the interpolated results are not fed back into the simulation - unless you're using a physics simulation to move the solver itself (eg. drive solver movement using a rigid body's interpolated position), in that case you will likely have issues caused by the interplay between interpolation and simulation.

So first thought has been to apply the velocities manually through the wind property (I think applying physics based velocities would remove the jitter here) - but inertias makes it tricky.
I like the effect of inertialWind of having Simulation space in World. So I think optimal would be having custom methods to be able to specify the current delta translation/velocity (linear+angular).

The world-space inertial delta is calculated by subtracting the solver's position in the last update from its current position (same for angular, but using quaternions instead). This is done right at the start of each physics step, so it should always be correct as long as the position of the solver is consistently updated.

kind regards,