Now that we have Changed<T>, optimize all the things

[cart]

We should be using Changed<T> everywhere we can to avoid doing redundant work:

• Transforms
• Parents/Children
• Labels
• Render Nodes
  • lights
  • camera
  • render_resources (potentially a huge win here)
• Cameras
• ShaderDefs
• Sprites
• UI update system (only update "dirty" parts of the tree)
• Pipeline Compiler (only run when RenderPipelines component has changed)

[tristanpemble]

I was looking into doing this for the transforms systems. For transform_translation_rotation_scale_system, the current query is:

Query<Without<LocalTransform, Without<NonUniformScale, (&mut Transform, &Translation, &Rotation, &Scale)>>>

ideally we could do something like

Query<Without<LocalTransform, Without<NonUniformScale, (&mut Transform, &Translation, &Rotation, &Scale, Any<Changed<Translation>, Changed<Rotation>, Changed<Scale>>)>>>

the idea being we want to run this system on anything that has Transform, Rotation and Scale, and at least one of those was changed.

I asked in Discord and it seems like this is not currently possible (tldr queries are and only, no or right now)

[tristanpemble]

@cart it may be worth changing your list into checkboxes so we can track status

[Axighi]

What's left for this task?

[chrisburnor]

What's left for this task?

Camera seems undone (from my cursory grepping through the codebase) but it's honestly kind of hard to figure out what has been done.

[cart]

Just updated the description with checkboxes indicating whats been done.

[cart]

I'm currently working on a rework of parenting/children. And #1046 is covering the ShaderDefs case.

[alice-i-cecile]

This should be looked at again once #68 is solved and we add explicit dependencies to our default systems for 0.5.

[thechubbypanda]

Bump, #68 has been cleared and I wanna help 😝

What's left to do?

[alice-i-cecile]

I would start by tackling the parent-child section of the code in your first PR.

RenderNodes, Sprites, and ShaderDefs are all being reworked; you'll have to work off of the pipelined-rendering branch for those.

UI update system has... larger issues, so it probably isn't worth the time right now.

[thechubbypanda]

Please see https://discord.com/channels/691052431525675048/692572690833473578/880354698647986197

I could be wrong but it looks like it's already done in #417. I may also not be looking at the right code.

[alice-i-cecile]

Yep, looks correct; seems like the list was just out-dated.

[cart]

Yeah I think we should probably close this issue out. Its from The Old Days™ and I don't think anything in the list is particularly relevant anymore.