Ragdoll physics are a new feature implemented in Grand Theft Auto IV. With ragdoll physics, the player and NPCs move, stagger, or fall down dynamically, depending on the location and severity of an attack or force (for example, being hit by a car or bullet). The affected model essentially behaves like a "ragdoll", hence the name. Ragdoll physics are mostly a graphical effect, but also affect gameplay -- when one is thrown from a vehicle, for example, the tumbling of the ragdoll dictates how much damage is inflicted. This renders motorcycle-riding a perilous option in GTA IV, compared to previous GTA games.
Ragdoll physics are implemented in the following situations (there may be others):
- When jumping out of a moving vehicle
- When being hit by a vehicle
- When burning
- When drunk
- When jumping from very high altitudes
- When dying
- When pushed by the protagonist (for NPCs)
- When shot (for NPCs). Both the protagonist and NPCs will "turn ragdoll" when thrown by an explosion.
- When on top of a moving train or car; the protagonist will "turn ragdoll", and fall off.
- When the player or NPCs are caught with their hand in the handle of a car while it is already moving.This causes them to be dragged for several meters and possibly to hit objects on the trajectory of the vehicle.
There are some modifications which allow the player to enable or disable ragdoll physics at any time; these can, however, cause glitches (characters being stuck inside objects, for example).