Odd physics body movement when ported to another platform (3DS)

[ds84182]

I ported Jolt to the 3DS (homebrew toolchain), which only required small changes related to memory allocation (specifically using the right aligned alloc functions). It currently uses the single threaded job system. Linear movement works fine, but angular movement is broken. When the box collides with the floor it starts hopping to the right, and when there is angular velocity applied the box completely disappears. When I increase the collision steps from 1 to 2 the box hops twice as fast.

The code is just the HelloWorld example hooked up to the default devkitPro textured cube example app, but with a box shape instead of a sphere for the dynamic body.

https://s3.draco.bark.dev/PXL_20260928_024353875.RAW.LS.mp4 (video uploaded to S3 bucket because it exceeds GitHub's file size limit)

[jrouwe]

I really don't know what this could be. My suggestion would be to make the UnitTests run on 3DS. Hopefully that will trigger a problem in one of the low level math functions that will help narrow this down. Please paste the output, and if the UnitTests crash somewhere then add an early out (after the check that fails) so that all tests at least complete (an early crash could hide the root cause in a later test).

[ds84182]

I really don't know what this could be. My suggestion would be to make the UnitTests run on 3DS. Hopefully that will trigger a problem in one of the low level math functions that will help narrow this down. Please paste the output, and if the UnitTests crash somewhere then add an early out so that all tests at least complete (an early crash could hide the root cause in a later test).

Got it running. Here's the output. I terminated it during the quaternion test since it spams the same assertion error to the log file.

Just looking at the failures themselves, they seem to all involve trigonometry functions somewhere. The convex hull test fails on the disc, which uses sin & cos to generate the positions.

Is it possible to just run the Vec4 tests?

[doctest] doctest version is "2.5.2"
[doctest] run with "--help" for options
===============================================================================
/home/ds/projects/dice3d/JoltPhysics/UnitTests/Core/FPFlushDenormalsTest.cpp:17:
TEST SUITE: FlushDenormalsTests
TEST CASE:  TestFlushDenormals

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Core/FPFlushDenormalsTest.cpp:22: ERROR: CHECK( value > 0.0f ) is NOT correct!
  values: CHECK( 0 >  0 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Core/FPFlushDenormalsTest.cpp:36: ERROR: CHECK( value > 0.0f ) is NOT correct!
  values: CHECK( 0 >  0 )

===============================================================================
/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:43:
TEST SUITE: ConvexHullBuilderTest
TEST CASE:  Test2DHull

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:86: ERROR: CHECK( builder.Initialize(0x7fffffff, cTolerance, error) == ConvexHullBuilder::EResult::Success ) is NOT correct!
  values: CHECK( 4 == 0 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:87: ERROR: CHECK( builder.GetNumVerticesUsed() == 10 ) is NOT correct!
  values: CHECK( 0 == 10 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:88: ERROR: CHECK( builder.GetFaces().size() == 2 ) is NOT correct!
  values: CHECK( 0 == 2 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:89: ERROR: CHECK( builder.ContainsFace({ 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 }) ) is NOT correct!
  values: CHECK( false )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:90: ERROR: CHECK( builder.ContainsFace({ 99, 98, 97, 96, 95, 94, 93, 92, 91, 90 }) ) is NOT correct!
  values: CHECK( false )

===============================================================================
/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:94:
TEST SUITE: ConvexHullBuilderTest
TEST CASE:  Test3DHull

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:132: ERROR: CHECK( builder.Initialize(0x7fffffff, cTolerance, error) == ConvexHullBuilder::EResult::Success ) is NOT correct!
  values: CHECK( 4 == 0 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/ConvexHullBuilderTest.cpp:133: ERROR: CHECK( builder.GetNumVerticesUsed() == 82 ) is NOT correct!
  values: CHECK( 0 == 82 )

===============================================================================
/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:126:
TEST SUITE: EPATests
TEST CASE:  TestEPASphereBox

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:56: ERROR: CHECK( angle < 0.1f ) is NOT correct!
  values: CHECK( 90 <  0.1 )

===============================================================================
/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:137:
TEST SUITE: EPATests
TEST CASE:  TestEPASphereSphereOverlapping

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:152: ERROR: CHECK( angle < 0.02f ) is NOT correct!
  values: CHECK( 90 <  0.02 )

===============================================================================
/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:155:
TEST SUITE: EPATests
TEST CASE:  TestEPASphereSphereNearOverlapping

/home/ds/projects/dice3d/JoltPhysics/UnitTests/Geometry/EPATests.cpp:171: ERROR: CHECK( angle < 0.02f ) is NOT correct!
  values: CHECK( 90 <  0.02 )

===============================================================================
/home/ds/projects/dice3d/JoltPhysics/UnitTests/Math/QuatTests.cpp:101:
TEST SUITE: QuatTests
TEST CASE:  TestQuatConvertMatrix

/home/ds/projects/dice3d/JoltPhysics/Build/../UnitTests/UnitTestFramework.h:59: ERROR: CHECK( close ) is NOT correct!
  values: CHECK( false )

/home/ds/projects/dice3d/JoltPhysics/Build/../UnitTests/UnitTestFramework.h:59: ERROR: CHECK( close ) is NOT correct!
  values: CHECK( false )

/home/ds/projects/dice3d/JoltPhysics/Build/../UnitTests/UnitTestFramework.h:59: ERROR: CHECK( close ) is NOT correct!
  values: CHECK( false )

/home/ds/projects/dice3d/JoltPhysics/Build/../UnitTests/UnitTestFramework.h:59: ERROR: CHECK( close ) is NOT correct!
  values: CHECK( false )

[ds84182]

I figured it out. It's a miscompilation due to LTO, and LTO is enabled by default. Disabling LTO fixes the issue.

When LTO was enabled, adding a call to SinCos from my project fixed the issue since it replaced the SinCos compiled by Jolt with one compiled in my own project.

static volatile float abc = 0.234;
JPH::Vec4 vs, vc;
JPH::Vec4::sReplicate(abc).SinCos(vs, vc);
std::printf("%f, %f\n", vs.GetX(), vc.GetX());

[jrouwe]

Looking at the 3DS CPU specs: 32-bit ARM should be supported and CI checks that it still works on every submit. This is checked in the emulator though, so there might be a difference with a real CPU.