Expose btCollisionObject interpolation transform and velocity accessors#446
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The failing CI here isn't caused by this change. I built and tested this change on a pinned emsdk 3.1.35 (the toolchain the committed I'll open a separate PR to repair the CI setup (pin emsdk so |
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Binds the six public btCollisionObject interpolation methods (world transform + linear/angular velocity get/set), available on btRigidBody and the other btCollisionObject subtypes via `implements`. Lets callers reset Bullet's interpolation state after setting a body's transform directly, so motion-state read-back is correct on frames that run zero fixed substeps. Adds tests/interpolation.js and rebuilds builds/* (emsdk 3.1.35). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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kripken
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Jun 16, 2026
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willeastcott
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Jun 17, 2026
… rates (#8915) * fix(physics): keep interpolation in sync on teleport for high refresh rates A dynamic body's teleport (syncEntityToBody) only set its world transform. On frames that run zero fixed sub-steps (dt < fixedTimeStep, e.g. high refresh-rate displays), Bullet fills the motion state by extrapolating from the stale interpolation transform, so the entity read back its pre-teleport pose (#4277, #7822). Reset the interpolation transform and linear/angular velocity for dynamic bodies, feature-detected so older ammo builds (lacking the bindings) no-op. Bundled ammo updated to the build exposing the btCollisionObject interpolation accessors (kripken/ammo.js#446). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * fix(physics): zero interpolation velocities so teleport read-back is exact Per review: copying the body's velocity into the interpolation state left the read-back within velocity*fixedTimeStep of the target (Bullet extrapolates from the interpolation transform by the leftover sub-step fraction). Zeroing the interpolation velocities makes getPosition() return exactly the teleport target on every frame, including for a moving body. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Binds the six public
btCollisionObjectinterpolation methods, which currently have no WebIDL bindings:get/setInterpolationWorldTransformset/getInterpolationLinearVelocityset/getInterpolationAngularVelocityThey're declared on
btCollisionObject, so via the existingimplementsthey're also available onbtRigidBody,btGhostObject, andbtSoftBody.Why: after setting a body's world transform directly (e.g. a teleport), Bullet's
synchronizeMotionStates()still extrapolates the motion state from the interpolation transform, whichsetWorldTransformdoesn't update. With these bound, a caller can reset the interpolation transform/velocities too, so motion-state read-back is correct even on frames that run zero fixed substeps. (Fixes the high-refresh teleport issue in PlayCanvas — playcanvas/engine#4277, playcanvas/engine#7822.)builds/*rebuilt with emsdk 3.1.35. Addstests/interpolation.js, which round-trips all six on abtRigidBody.