Fixed determinism of CharacterVirtual test (#386)

Jolt/Physics/Character/CharacterBase.cpp

@@ -26,7 +26,7 @@ void CharacterBase::SaveState(StateRecorder &inStream) const
 	inStream.Write(mGroundPosition);
 	inStream.Write(mGroundNormal);
 	inStream.Write(mGroundVelocity);
-	// Can't save or restore user data (may be a pointer) and material
+	// Can't save user data (may be a pointer) and material
 }
 
 void CharacterBase::RestoreState(StateRecorder &inStream)
@@ -37,6 +37,8 @@ void CharacterBase::RestoreState(StateRecorder &inStream)
 	inStream.Read(mGroundPosition);
 	inStream.Read(mGroundNormal);
 	inStream.Read(mGroundVelocity);
+	mGroundUserData = 0; // Cannot restore user data
+	mGroundMaterial = nullptr; // Cannot restore material
 }
 
 JPH_NAMESPACE_END

Jolt/Physics/Character/CharacterVirtual.cpp

@@ -1307,6 +1307,41 @@ void CharacterVirtual::ExtendedUpdate(float inDeltaTime, Vec3Arg inGravity, cons
 	}
 }
 
+void CharacterVirtual::Contact::SaveState(StateRecorder &inStream) const
+{
+	inStream.Write(mPosition);
+	inStream.Write(mLinearVelocity);
+	inStream.Write(mContactNormal);
+	inStream.Write(mSurfaceNormal);
+	inStream.Write(mDistance);
+	inStream.Write(mFraction);
+	inStream.Write(mBodyB);
+	inStream.Write(mSubShapeIDB);
+	inStream.Write(mMotionTypeB);
+	inStream.Write(mHadCollision);
+	inStream.Write(mWasDiscarded);
+	inStream.Write(mCanPushCharacter);
+	// Cannot store user data (may be a pointer) and material
+}
+
+void CharacterVirtual::Contact::RestoreState(StateRecorder &inStream)
+{
+	inStream.Read(mPosition);
+	inStream.Read(mLinearVelocity);
+	inStream.Read(mContactNormal);
+	inStream.Read(mSurfaceNormal);
+	inStream.Read(mDistance);
+	inStream.Read(mFraction);
+	inStream.Read(mBodyB);
+	inStream.Read(mSubShapeIDB);
+	inStream.Read(mMotionTypeB);
+	inStream.Read(mHadCollision);
+	inStream.Read(mWasDiscarded);
+	inStream.Read(mCanPushCharacter);
+	mUserData = 0; // Cannot restore user data
+	mMaterial = nullptr; // Cannot restore material
+}
+
 void CharacterVirtual::SaveState(StateRecorder &inStream) const
 {
 	CharacterBase::SaveState(inStream);
@@ -1314,6 +1349,18 @@ void CharacterVirtual::SaveState(StateRecorder &inStream) const
 	inStream.Write(mPosition);
 	inStream.Write(mRotation);
 	inStream.Write(mLinearVelocity);
+	inStream.Write(mLastDeltaTime);
+	inStream.Write(mMaxHitsExceeded);
+
+	// Store contacts that had collision, we're using it at the beginning of the step in CancelVelocityTowardsSteepSlopes
+	uint32 num_contacts = 0;
+	for (const Contact &c : mActiveContacts)
+		if (c.mHadCollision)
+			++num_contacts;
+	inStream.Write(num_contacts);
+	for (const Contact &c : mActiveContacts)
+		if (c.mHadCollision)
+			c.SaveState(inStream);
 }
 
 void CharacterVirtual::RestoreState(StateRecorder &inStream)
@@ -1323,6 +1370,20 @@ void CharacterVirtual::RestoreState(StateRecorder &inStream)
 	inStream.Read(mPosition);
 	inStream.Read(mRotation);
 	inStream.Read(mLinearVelocity);
+	inStream.Read(mLastDeltaTime);
+	inStream.Read(mMaxHitsExceeded);
+
+	// When validating remove contacts that don't have collision since we didn't save them
+	if (inStream.IsValidating())
+		for (int i = (int)mActiveContacts.size() - 1; i >= 0; --i)
+			if (!mActiveContacts[i].mHadCollision)
+				mActiveContacts.erase(mActiveContacts.begin() + i);
+
+	uint32 num_contacts = (uint32)mActiveContacts.size();
+	inStream.Read(num_contacts);
+	mActiveContacts.resize(num_contacts);
+	for (Contact &c : mActiveContacts)
+		c.RestoreState(inStream);
 }
 
 JPH_NAMESPACE_END

Jolt/Physics/Character/CharacterVirtual.h

@@ -270,6 +270,10 @@ public:
 	// Encapsulates a collision contact
 	struct Contact
 	{
+		// Saving / restoring state for replay
+		void							SaveState(StateRecorder &inStream) const;
+		void							RestoreState(StateRecorder &inStream);
+
 		RVec3							mPosition;												///< Position where the character makes contact
 		Vec3							mLinearVelocity;										///< Velocity of the contact point
 		Vec3							mContactNormal;											///< Contact normal, pointing towards the character

Samples/Tests/Character/CharacterVirtualTest.cpp

@@ -142,6 +142,7 @@ void CharacterVirtualTest::SaveState(StateRecorder &inStream) const
 	bool is_standing = mCharacter->GetShape() == mStandingShape;
 	inStream.Write(is_standing);
 
+	inStream.Write(mAllowSliding);
 	inStream.Write(mDesiredVelocity);
 }
 
@@ -155,6 +156,7 @@ void CharacterVirtualTest::RestoreState(StateRecorder &inStream)
 	inStream.Read(is_standing);
 	mCharacter->SetShape(is_standing? mStandingShape : mCrouchingShape, FLT_MAX, { }, { }, { }, { }, *mTempAllocator);
 
+	inStream.Read(mAllowSliding);
 	inStream.Read(mDesiredVelocity);
 }