Editing Crowd simulation (section)

=== Scalable simulations ===
There are many different case situations that come into play in crowd simulations.<ref>{{cite book |doi=10.1109/ICPP.2008.20 |chapter=A Scalable Architecture for Crowd Simulation: Implementing a Parallel Action Server |title=2008 37th International Conference on Parallel Processing |pages=430–7 |year=2008 |last1=Vigueras |first1=G. |last2=Lozano |first2=M. |last3=Pérez |first3=C. |last4=Orduña |first4=J.M. }}</ref> Recently, crowd simulation has been essential for the many virtual environment applications such as education, training, and entertainment.  Many situations are based on the environment of the simulation or the behavior of the group of local agents.  In virtual reality applications, every agent interacts with many other agents in the environment, calling for complex real-time interactions.  Agents must have continuous changes in the environment since agent behaviors allow complex interactions.  Scalable architecture can manage large crowds through the behavior and interactive rates.  These situations will indicate how the crowds will act in multiple complex scenarios while several different situations are being applied.  A situation can be any circumstance that has typical local behaviors.  We can categorize all situations into two different kinds.

''Spatial situation'' is a situation that has a region where the environment affects the local agents.  For instance, a crowd waiting in line for a ticket booth would be displaying a spatial situation. Other examples may be a bus stop or an ATM where characters act upon their environment.  Therefore, we would consider 'bus stop' as the situation if the behavior of the agents are to be getting on or off a bus.

''Non-Spatial situation'' has no region in the environment because this only involves the behavior of the crowd.  The relationship of the local agents is an important factor to consider when determining behavior.  An example would be a group of friends walking together.  Typical behavior of characters that are friends would all move along with each other. This means that 'friendship' would be the situation among the typical behavior of walking together.

The structure of any situation is built upon four components, Behavior functions, Sensors, States, and Event Rules.  Behavior functions represent what the characters behaviors are specific to the situation.  Sensors are the sensing capability for agents to see and respond to events.  States are the different motions and state transitions used only for the local behaviors.  Event rule is the way to connect different events to their specific behaviors.  While a character is being put into a situation, these four components are considered at the same time.  For spatial situations,  the components are added when the individual initially enters the environment that influences the character.  For non-spatial situations, the character is affected only once the user assigns the situation to the character.  The four components are removed when the agent is taken away from its situations region or the situation itself is removed.  The dynamic adding and removing of the situations lets us achieve scalable agents.