Hit an assert in DynamicsWorld::integrateRigidBodiesVelocities

[andreasdr]

Hi,

I am hitting an assert when moving a dynamic rigid body into a static rigid body(also into a collision body).

Assertion failed: (mSplitLinearVelocities[indexBody] == Vector3(0, 0, 0)), function integrateRigidBodiesVelocities, file ext/reactphysics3d/src/engine/DynamicsWorld.cpp, line 297.

The game crashes then. Also when disabling asserts.

The backtrace looks like:

(gdb) bt
#0  0x00000000005c0030 in reactphysics3d::CollisionBody::updateProxyShapeInBroadPhase ()
#1  0x00000000005bfe1d in reactphysics3d::CollisionBody::updateBroadPhaseState ()
#2  0x00000000005a993c in reactphysics3d::DynamicsWorld::updateBodiesState ()
#3  0x00000000005a88c7 in reactphysics3d::DynamicsWorld::update ()
#4  0x00000000004709a4 in tdme::engine::physics::World::update ()
#5  0x00000000004172f6 in asw::ASWClientGameLogicThread::run ()
#6  0x00000000004f055a in tdme::os::threading::Thread::pThreadRun ()
#7  0x0000000801ef9bc5 in pthread_create () from /lib/libthr.so.3
#8  0x0000000000000000 in ?? ()

I will try to get a backtrace of debug build soon too.

Best regards
Andreas

[andreasdr]

Hi

Backtrace with debug build looks like:

(gdb) bt
#0  0x000000000050846a in reactphysics3d::Vector3::operator= (this=0x83a3704f8, vector=@0x7fffdfbfa750) at Vector3.h:360
#1  0x00000000009e7bfa in reactphysics3d::DynamicsWorld::integrateRigidBodiesVelocities (this=0x8062b0000) at ext/reactphysics3d/src/engine/DynamicsWorld.cpp:301
#2  0x00000000009e7278 in reactphysics3d::DynamicsWorld::update (this=0x8062b0000, timeStep=0.0160000008) at ext/reactphysics3d/src/engine/DynamicsWorld.cpp:132
#3  0x00000000004ebdbb in tdme::engine::physics::World::update (this=0x8062b0000, deltaTime=0.0160000008) at src/tdme/engine/physics/World.cpp:179

I need collision bodies for several game features.

Best regards
Andreas

[DanielChappuis]

Hello. It seems to happen in the call of the DynamicsWorld.update() method. Are you doing something special in your code before you call this method (between this call and the previous one) ? Like adding, removing bodies from the world ?

Also, where the assert is hit, can I ask you what is the value of the variables "indexBody" and "mSplitLinearVelocities.size()" ?

[andreasdr]

I will do today.

[andreasdr]

I am adding a collision body in a frame and then just remove it after several frames(means after several world.update() calls). So nothing special at all. Meanwhile I do not add or remove bodies.

[andreasdr]

I have added the following line to debug:

Console::println(to_string(mBodies.size()) + ":" + to_string(indexBody));

(mSplitLinearVelocities is a C++ Array, not a STL container or something)

Before the game crashes it prints:
573:6337680
573:571

[andreasdr]

Oh overread that too fast.

Also, where the assert is hit, can I ask you what is the value of the variables "indexBody" and "mSplitLinearVelocities.size()" ?

I will check tomorrow. I have made changes to TDME2 that requires me to modify game logics too.

[andreasdr]

Hi,

please see attached a patch that fixes the crash.

diff --git a/ext/reactphysics3d/src/engine/DynamicsWorld.cpp b/ext/reactphysics3d/src/engine/DynamicsWorld.cpp
index 91112d74..68eff2ab 100644
--- a/ext/reactphysics3d/src/engine/DynamicsWorld.cpp
+++ b/ext/reactphysics3d/src/engine/DynamicsWorld.cpp
@@ -746,13 +746,18 @@ void DynamicsWorld::computeIslands() {
                 // Check if the current contact manifold has already been added into an island
                 if (contactManifold->isAlreadyInIsland()) continue;
 
+                // Get the other body of the contact manifold
+                RigidBody* body1 = dynamic_cast<RigidBody*>(contactManifold->getBody1());
+                RigidBody* body2 = dynamic_cast<RigidBody*>(contactManifold->getBody2());
+
+                // if body1 or body2 is nullptr dynamic cast have failed due to beeing collision body
+                if (body1 == nullptr || body2 == nullptr) continue;
+
                 // Add the contact manifold into the island
                 mIslands[mNbIslands]->addContactManifold(contactManifold);
                 contactManifold->mIsAlreadyInIsland = true;
 
-                // Get the other body of the contact manifold
-                RigidBody* body1 = static_cast<RigidBody*>(contactManifold->getBody1());
-                RigidBody* body2 = static_cast<RigidBody*>(contactManifold->getBody2());
+                //
                 RigidBody* otherBody = (body1->getId() == bodyToVisit->getId()) ? body2 : body1;
 
                 // Check if the other body has already been added to the island
@@ -781,6 +786,10 @@ void DynamicsWorld::computeIslands() {
                 // Get the other body of the contact manifold
                 RigidBody* body1 = static_cast<RigidBody*>(joint->getBody1());
                 RigidBody* body2 = static_cast<RigidBody*>(joint->getBody2());
+

Best regards
Andreas

[DanielChappuis]

Yes thanks. I have also found how to solve it yesterday evening with this commit. I was just running some tests to see that this fix was OK. I think our patches are similar.

I have pushed my changes into the develop branch. Could you test if the issue is also resolved on your side with the develop branch ?

[andreasdr]

Ok. Nice. Will test later today.

[andreasdr]

Seems to be fixed. Thank you.

[DanielChappuis]

Ok Thanks. The fix is now merged in the master branch.