Death - widberg/fmtk GitHub Wiki

In FUEL, when you die, the game will play the death RTC, TR_DEATH, respawn you according to the Respawn Behavior, and reset various properties of the vehicle. The game will also play the RTC when you exit menus, teleport, and do other stuff, but those don't count as deaths in my opinion.

The vehicle is considered on its side if the squared Euclidean distance (SED) between its normalized up vector and the normal of the ground below it, even if it's not touching the ground, is greater than or equal to 0.25. If it looks like it's on its side, the game probably agrees. The vehicle tracks how long it has been on its side. If it is dead or isn't on its side for a frame, it will reset the timer to 0; otherwise, it adds the delta time to the timer each frame. The vehicle is considered on the ground if at least one wheel is touching the ground. This first set of conditions is all together and plays the death RTC immediately; they are checked both on the ground and in the air. They don't set the dead flag on the vehicle. If the time spent on the side is greater than 1.0 second and you are moving at less than 2.0 meters/s, you die. If you are moving at 2.0 meters/s or more and the time spent on the side is greater than 2.0, you die.

This next set of conditions is grouped; they set the dead flag on the vehicle, and at the end of the function, it does the death stuff if it's set. These run after the previous conditions, even if they killed you, since those don't set the dead flag. These first three conditions are checked on the ground and in the air. If the ForceDestroyVehicle command is set and some flag on the vehicle related to whether it's controllable is not set, the dead flag gets set. If you take too much damage, dead flag. Being in water applies 100% damage to a part of the vehicle, so death by drowning is handled by death by damage code. If the SED between the vehicle's up vector and ground normal is less than -0.30000001, dead flag.

These conditions are part of the same group as the last three, but they only get set on the ground. If you are moving sideways faster than vehicle parameter vp599 meters/s, death. If the SED between the up vector and the ground vector is less than vp627, believe it or not, death. These last two conditions happen on the frame you land if you were in the air for longer than vp628 seconds. If the SED between the forward/backward vector and the ground normal is more than vp629, death. If the SED between the left/right vector and the ground normal is more than vp630, death.

There's one final condition in that same group, ground or air, that checks if the vehicle has been closer than it should be to objects in some list for more than 1.0 second. If so, it sets the dead flag to 2 instead of 1 like everything else, it also sets a member of the script manager to 1. It only checks if it's 2 in one place; otherwise, it's just checking if it's equal to 0 or not, so setting it to 2 enables a superset of the behavior of setting it to 1. The list of objects it's checking against seems to always be empty. I don't really know what this is for.

You can also die by going past the out-of-area border or manually resetting yourself, both of which are handled separately and are described more on the Respawn Behavior page.

The death code is super janky. They do it differently in several places and rely on side effects, eventually causing death, such as how drowning is handled. Sometimes the death RTC will play twice back-to-back and look like it's overlapping, because of the disagreements for how to check if the vehicle is dead. It's way too easy to die sliding down terrain because of all the ground normal calculations. Also, the angle of impact checks when landing a jump are probably too strict, especially when trying to go down a mountain.

As far as I could find, there isn't anything that kills you in the air if you fall for too long or too fast. The only ways I can imagine dying while in the air, given the above information, are flipping over, hitting something, going near one of the objects in the list, or the weird ForceDestroyVehicle thing. It's possible that while in the air, you pass over some steep terrain at an angle and die because the game thinks you flipped over. And you mistake that for some kind of airtime timeout. It's also possible, but unlikely, that I haven't found all the ways to die. The system is too complicated for me to claim I understand it completely with confidence.