Skip to content

feat(physics): allow gamepieces to sleep & adding simulation debt into timestep#1421

Draft
Dhruv-0-Arora wants to merge 10 commits into
devfrom
darora1/257/timestepping-and-sleep
Draft

feat(physics): allow gamepieces to sleep & adding simulation debt into timestep#1421
Dhruv-0-Arora wants to merge 10 commits into
devfrom
darora1/257/timestepping-and-sleep

Conversation

@Dhruv-0-Arora

@Dhruv-0-Arora Dhruv-0-Arora commented Jul 17, 2026 •
edited
Loading

Copy link
Copy Markdown
Collaborator

Important

The way that gamepieces go to sleep when the field first spawns is something we should look into:
Currently, they are set to sleep (in this PR) however the MirabufSceneObject instantly wakes them up to move them to their desired location. This will tank performance for the first ~5 seconds while the gamepieces wait to go back to sleep.

SYNTH-257

Before merging, ensure the following criteria are met:

  • All acceptance criteria outlined in the ticket are met.
  • Necessary test cases have been added and updated.
  • A feature toggle or safe disable path has been added (if applicable).
  • User-facing polish:
    • Ask: "Is this ready-looking?"
  • Cross-linking between Jira and GitHub:
    • PR links to the relevant Jira issue.
    • Jira ticket has a comment referencing this PR.

@Dhruv-0-Arora
feat(physics): allow gamepiece bodies to sleep & timestepping
da7201d 
timestepping: adding simulation timedebt for when FPS dropping

Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora
ci(physics): testing sleeping gamepieces
210ea86 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora Dhruv-0-Arora self-assigned this Jul 17, 2026
@Dhruv-0-Arora
Dhruv-0-Arora requested review from a team as code owners July 17, 2026 00:15
@Dhruv-0-Arora
Dhruv-0-Arora force-pushed the darora1/257/timestepping-and-sleep branch 2 times, most recently from ab6c1dd to 3eb1cd4 Compare July 17, 2026 00:55
@Dhruv-0-Arora Dhruv-0-Arora mentioned this pull request Jul 17, 2026
Merged
Dhruv-0-Arora
Dhruv-0-Arora commented Jul 17, 2026
View reviewed changes
Comment thread fission/src/systems/physics/PhysicsSystem.ts
@Dhruv-0-Arora
fix(physics): robot jitter caused by substep change
1b0a76d 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora
Dhruv-0-Arora force-pushed the darora1/257/timestepping-and-sleep branch from 3eb1cd4 to 1b0a76d Compare July 17, 2026 01:15
@Dhruv-0-Arora
ci(physics): fixing robot jitter tests
5c391f6 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora
Dhruv-0-Arora force-pushed the darora1/257/timestepping-and-sleep branch from 9788651 to 5c391f6 Compare July 17, 2026 01:26
AlexD717
AlexD717 requested changes Jul 17, 2026
View reviewed changes

@AlexD717 AlexD717 left a comment •
edited
Loading

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Drag Mode is broken

Fission._.Synthesis.-.Google.Chrome.2026-07-17.09-08-48.mp4

It appears that you can't use drag mode for objects that are asleep, but the force is still applied once they wake up.

In addition, jittering is a bit worse on my MacBooks 120hz monitor, but still happens on my home desktop (weaker computer and 60hz monitor).

rutmanz
rutmanz requested changes Jul 17, 2026
View reviewed changes

@rutmanz rutmanz left a comment

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Screen.Recording.2026-07-17.at.10.13.24.AM.mov

Like @AlexD717 noticed, Dozer jitters now in a way it doesn't on dev (this is on my work laptop)

Comment thread fission/src/systems/physics/PhysicsSystem.ts Outdated
// driver stiffness independent of construction-time frame rate.
export function getLastDeltaT(): number {
return lastDeltaT
return STANDARD_SIMULATION_PERIOD

@rutmanz rutmanz Jul 17, 2026

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

this should probably be removed. This name implies it is the last delta t and that it changes, when it is actually a constant (that can be referenced directly where this is used)

Comment thread fission/src/systems/physics/PhysicsSystem.ts Outdated
azaleacolburn
azaleacolburn requested changes Jul 17, 2026
View reviewed changes
Comment thread fission/src/systems/physics/PhysicsSystem.ts Outdated
Comment thread fission/src/systems/physics/PhysicsSystem.ts Outdated
Comment thread fission/src/systems/physics/PhysicsSystem.ts Outdated
Comment thread fission/src/systems/physics/PhysicsSystem.ts
Comment thread fission/src/systems/physics/PhysicsSystem.ts
@Dhruv-0-Arora

Dhruv-0-Arora commented Jul 18, 2026

Copy link
Copy Markdown
Collaborator Author

@AlexD717 @rutmanz I'm not able to reproduce the robot jitter that you experienced. Does dozer jitter when you initially spawn it for the first time on an empty field?

Dhruv-0-Arora and others added 5 commits July 17, 2026 18:15
@Dhruv-0-Arora @azaleacolburn
docs(physics): suggested documentation changes regarding bodies sleeping
ba544c0 
Co-authored-by: Azalea Colburn <62953415+azaleacolburn@users.noreply.github.com>
@Dhruv-0-Arora
fix(physics): dragmode doesn't work on sleeping bodies
d7cf622 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora
ci(dragmode): sleeping bodies on drag mode test
8d3b197 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora
chore(physics): reverting linear cast change
5741cd2 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora
chore(physics): removing and cleaning getLastDeltaT
63632ae 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@AlexD717

AlexD717 commented Jul 20, 2026

Copy link
Copy Markdown
Member

@AlexD717 @rutmanz I'm not able to reproduce the robot jitter that you experienced. Does dozer jitter when you initially spawn it for the first time on an empty field?

For me, this really only happens on the 2026 field after I go in and push some balls around (once the fps recovers the jittering starts to slow down and eventually goes away). If you are struggling to reproduce it try throttling your CPU (it makes the jittering a lot worse for me).

@Dhruv-0-Arora
fix(physics): floor collision steps at the coarsest stable substep
785f09b 
Signed-off-by: Dhruv Arora <dhruv.arora1@autodesk.com>
@Dhruv-0-Arora
Dhruv-0-Arora force-pushed the darora1/257/timestepping-and-sleep branch from f80dac9 to 785f09b Compare July 20, 2026 23:10
@Dhruv-0-Arora
Dhruv-0-Arora marked this pull request as draft July 22, 2026 00:54
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@rutmanz rutmanz rutmanz requested changes
@AlexD717 AlexD717 AlexD717 requested changes
@azaleacolburn azaleacolburn azaleacolburn requested changes
@0xda157 0xda157 Awaiting requested review from 0xda157 0xda157 is a code owner automatically assigned from Autodesk/fission
@PepperLola PepperLola Awaiting requested review from PepperLola PepperLola is a code owner automatically assigned from Autodesk/synthesis-admin

Requested changes must be addressed to merge this pull request.

Assignees

@Dhruv-0-Arora Dhruv-0-Arora

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

4 participants

@Dhruv-0-Arora @AlexD717 @azaleacolburn @rutmanz