Euphoria is a game engine animation software developed by NaturalMotion, most well known in the context of Grand Theft Auto for its incorporation into the Rockstar Advanced Game Engine (RAGE), which Grand Theft Auto IV runs on, for use in advanced character procedural animation and ragdoll physics.
Since GTA IV, Euphoria has received updates and is utilized again in Red Dead Redemption, another RAGE game and Max Payne 3.
The software allows pedestrian models in GTA IV, including the player, to perform animated movements more naturally by utilizing "on-the-fly" animation programming generated exactly as the player interacts with the player character, as opposed to fetching scripted animations in previous GTA games; this allows pedestrians to seamlessly execute different animated sequences (like tilting while walking and turning around a corner, or thrusting their arms forward when pushing against doors or pedestrians). Due to the nature of the software, no one animation cycle is the same. The system covers nearly all in-game animated behaviors, including firearm usage, hand-to-hand combat, jumps and climbs, recoveries and interactions with in-world objects.
In addition to enhanced animation cycles, RAGE's Euphoria is also designed to provide more life-like animations by giving each live pedestrian autonomy to flail, flip, attempt to stay standing when forced against the player character or an object, land upright, or continue to move after falling to the ground. Characters in a drunken state are also excellent examples of this feature in action.
Animations under the control of Euphoria does allow control to a limited extent. This is especially noticeable when being drunk. Pushing the directional key to a certain direction will allow the player character to move towards that direction. This also applies to tumbling after being ejected from a vehicle. It is possible to indefinitely tumble with enough speed, health, and by pushing the directional key towards the direction of tumble.
Euphoria is generally associated to live characters in RAGE, and should not be confused with ragdoll, which is associated to dead characters in RAGE. Unlike Euphoria, when characters are in ragdoll mode, the entire model will limp onto the ground and will not react with self-preservation. It is possible to enable ragdoll mode while alive through the use of modifications or trainers only.
- A predecessor in the GTA series of the Euphoria's basic animation engine is a three-point system employed in RenderWare games, where the player's head, upper body (upper torso and arms), and lower body (lower torso and legs) are individually animated based on their interaction with their surroundings. Of interesting note is the ability for a pedestrian's head and upper torso to turn towards any vehicle or pedestrian that they bump into.
In Grand Theft Auto: San Andreas, this animation system is extended to the player's head when driving a vehicle, allowing the player character to look to the direction of any vehicle they recently had an accident with.