In the game I am working on I am simulating physics on certain bones in the character meshes. These are used to simulate things like antennas and armor plates behaving realistically as the character moves around in game. Additionally the upper body simulates physics when the character receives enough damage in a short amount of time.
This works as intended when I click on Play in editor, however, when I click launch, or I build and launch the .exe directly the physics behavior is less than stellar. Some physics bones do not animate for a very short amount of time, then stop physics simulation all together. When the character gets hit the arms fall off, then reattach when the physics blend is set back to zero. And ragdolls consistently fall through world geometry.
My first guess would be a performance issue, that there is not enough processing power available for the physics processing required. However the simulation runs at between 45 and 60 fps in the editor, and between 60 and 75 fps when the .exe is run. Additionally enabling physics sub stepping has no apparent effect.
A short clip of the wonky physics behavior can be seen here: - YouTube
I’m observing similiar issue, my car simulation runs in async scene and in the editor simulation looks normal, but when game is started with exe ("-game" switch), the car simulation looks weird.
A bit of an addendum: My project is 100% blueprint based. A simple blueprint actor with a skeletal mesh, that is set to simulate physics in the begin play event appears to work properly.
Time to investigate and see if I cant narrow it down to a certain function that is causing the different behavior between PIE and a full game launch.
I am still having this issue. I have managed to upload a short video of what the physics look like when played in the editor, it can be seen at: - YouTube
I have narrowed it down to hopefully one of two classes, but can not make heads of tails of what is actually causing the odd physics behavior in the packaged game. No physics based animation works for the parent (blueprint) class of all the mobile characters in my game, it is named Mobile_Char. In an attempt to narrow the issue down to a certain function or variable I created another class and began copying functions over one at a time from the already existing Mobile_Char class. I added a function to ragdoll this character 5 seconds after beginplay was called so I could test it in game. The ragdoll worked properly with all functions and variables identical between Mobile_Char and the test blueprint. The next step I took was to start up the AI. Specifcally attach the AI controller named MAIC (Mobile AI Controller) to the test character. The ragdolls did still work properly at this time.
I then changed the references in MAIC from Mobile_Char to the new test character so that MAIC could properly control the test character. It was at this point that the ragdolls broke (and all physics based animation)
Setting the test character’s ai controller to the base ai controller still resulted in broken ragdolls.
Disabling all functions in MAIC still resulted in broken ragdolls.
As near as I can tell the broken physics is caused by the ai controller (MAIC) having a reference to Mobile_Char (the character class I am attempting to run physics simulation on) My best guess is that this is caused by one or more blueprints having unresolved references (to not yet compiled classes) when they are compiled. I am not sure if this explains why everything behaves properly in the editor, and does not behave properly in the packaged game.
I would greatly appreciate help in solving this problem.
I was having the same issue, and it looks like its a bug with the physics implementation. It has been reported - take a look here and keep an eye on it for info on the fix.