Winit Decoupling

[NthTensor]

Goal Description

The ECS and winit have grown closely intertwined, largely because ECS updates run within the windowing event loop. For various reasons, this is blocking some hotly desired features (frame-pacing and accurate input timestamps, for example). The close coupling also makes it hard to use alternative windowing backends like SDL. We intend to instead move the ECS onto it's own thread, so ECS updates can occur independently of windowing updates. The ECS and windowing will instead communicate via message passing.

Goal Status

This is a potential Bevy Project Goal. Its state on the Project Goals Board determines if it is Proposed, Postponed, Blocked (Approved), Inactive (Approved), Active (Approved), Completed, or Declined.

• Staffing SMEs: Not yet staffed
• Working Group Link: Working Group not yet formed
• Design Documents: https://hackmd.io/@bevy/winit_refactorening

[NthTensor]

@tychedelia has already done a lot of work on this, but can't technically staff it at the moment.

[alice-i-cecile]

@IceSentry has also experimented with an SDL2 windowing backend. We don't intend to swap, but experience there will help guide us on where the API boundaries should lie. Another key reason why someone might want to swap windowing backends: consoles.

[NthTensor]

Since this isn't technically staffed, but I believe cart has informally blessed the proposal, should this move to the Postponed status? Or is this still proposed?

[alice-i-cecile]

I'll let Cart do the formal moving, but I agree that that's what we should decide to do here :)