Search Issue Tracker
By Design
Votes
3
Found in
2018.3.0a5
2019.1.12f1
2019.2.0a1
2019.3.0a1
2020.1.0a1
Issue ID
1181054
Regression
No
Rigidbody with "Continuous Speculative" produces different results when changing IsKinematic and the moving object is fast
How to reproduce:
1. Open attached project "Kinematic_Speculative.zip" and scene "SampleScene"
2. Enter Play mode and observe how many Cubes does the Bullet hit
3. Exit Play mode
4. In Hiearachy window, select "Bullet" object
5. In Inspector window, "Rigidbody" component -> change "Is Kinematic" to false
6. Repeat step 2
Expected result: only the middle cube is hit
Actual result: with "Is Kinematic" set to true there are more than 1 hit cube
Reproducible with: 2018.3.0a5, 2018.4.8f1, 2019.2.4f1, 2019.3.0b2, 2020.1.0a3
Not reproducible with: 2017.4.32f1, 2018.3.0a4
Add comment
All about bugs
View bugs we have successfully reproduced, and vote for the bugs you want to see fixed most urgently.
Latest issues
- Out-of-bounds memory access with multiple CanvasRenderers under a Canvas when using Mesh API
- Inspector tries to access file after it was deleted when the file was locked in Inspector window
- Changing Transform values in Search window Inspector loses focus while dragging and stopping mouse without releasing dragging action
- Saving changes on the dirty VFX Graph during the Play mode throws "The referenced script (Unknown) on this Behaviour is missing!" warnings
- VFX Graph Debug Info overlaps the "Initialize" block debug info by default
Resolution Note:
False positives is the normal behaviour of the speculative collision detection in PhysX because all it does is inflates the contact offsets when the collisions start being detected proportionally to the linear and angular velocities. You see the difference dynamic vs kinematic here because dynamic is being teleported via transform essentially while the kinematic is driven by a kinematic goal that leads to the computation of high velocities => higher inflation that results in more false positives in the end. See PhysX code here: https://github.com/NVIDIAGameWorks/PhysX/blob/ae80dede0546d652040ae6260a810e53e20a06fa/physx/source/simulationcontroller/src/ScBodySim.cpp#L216