Kinematic bodies, inactive GameObjects, and collider migration onto a new Rigidbody #72

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opened 2026-09-05 09:37:00 +00:00 by crowmaki · 0 comments

crowmaki commented

2026-09-05 09:37:00 +00:00

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Parent

Part of #67.

What to build

The remaining body kinds and lifecycle edges work. A kinematic Rigidbody copies its GameObject's World Transform into its body before each step, so moving it with the Scene API moves it in the world and a dynamic cube resting on it is carried. A Rigidbody whose GameObject is not Active in Hierarchy has its body disabled on the step it is first seen inactive and re-enabled when seen active again, so it neither moves nor blocks. Adding a Rigidbody to a GameObject that already carries Box_Colliders on an Implicit Static Body recreates their shapes on the new body and destroys the implicit one.

Acceptance criteria

A kinematic body moved with the Scene API is where it was put after the step, and a dynamic cube resting on it moves with it.
Deactivating a falling cube's GameObject freezes its World Transform; reactivating resumes the fall.
Adding a Rigidbody to a collider-only GameObject makes it fall, and body_count does not double-count the migrated object.
Every test runs Headless in the core suite.

Blocked by

#71 A cube falls onto a plane

## Parent Part of #67. ## What to build The remaining body kinds and lifecycle edges work. A kinematic `Rigidbody` copies its GameObject's World Transform into its body before each step, so moving it with the Scene API moves it in the world and a dynamic cube resting on it is carried. A `Rigidbody` whose GameObject is not Active in Hierarchy has its body disabled on the step it is first seen inactive and re-enabled when seen active again, so it neither moves nor blocks. Adding a `Rigidbody` to a GameObject that already carries `Box_Collider`s on an Implicit Static Body recreates their shapes on the new body and destroys the implicit one. ## Acceptance criteria - [ ] A kinematic body moved with the Scene API is where it was put after the step, and a dynamic cube resting on it moves with it. - [ ] Deactivating a falling cube's GameObject freezes its World Transform; reactivating resumes the fall. - [ ] Adding a `Rigidbody` to a collider-only GameObject makes it fall, and `body_count` does not double-count the migrated object. - [ ] Every test runs Headless in the core suite. ## Blocked by - #71 A cube falls onto a plane

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2026-09-05 09:37:09 +00:00

crowmaki referenced this issue from a commit

2026-09-07 00:38:42 +00:00

Kinematic bodies and inactive GameObjects in the box3d Plugin (#72)

crowmaki referenced this issue from a commit

2026-09-07 00:38:42 +00:00

A disabled body is not written back, and a test that it does not block (#72)

crowmaki referenced this issue from a pull request that will close it,

2026-09-07 00:38:47 +00:00