AI and Game ProgrammingSelected AI TechniquesDeterministic AlgorithmsRandom MotionTracking and PursuitTracking and EvasionPatterns and ScriptsBehavioral State SystemsMemory and LearningDeciding Between AI Techniques1AI and Game ProgrammingCIS 487/587Bruce R. MaximUM-Dearborn2Selected AI Techniques•Deterministic algorithms•Heuristic programming•Patterns and scripts•Finite state machines•Production systems•Genetic algorithms•Neural networks3Deterministic Algorithms •Each clock tickasteroid_x += asteroid_x_velocityasteroid_y += asteroid_y_velocity•Asteroids follow their course until–off screen–collision occurs–blown up4Random Motionfly_x = rand() % 80fly_y= rand() % 80while(~done()){fly_count = 0fly_x_velocity = -8 + rand() % 16fly_y_velocity = -8 + rand() % 16while (++fly_count < 10){fly_x += fly_x_velocityfly_y += fly_y_velocity}5Tracking and Pursuitif (player_x > monster_x)monster_x++if (player_x < monster_x)monster_x--if (player_y > monster_y)monster_y++if (player_y < monster_y)monster_y--6Tracking and Evasionif (player_x < monster_x)monster_x++if (player_x > monster_x)monster_x--if (player_y < monster_y)monster_y++if (player_y > monster_y)monster_y--7Patterns and Scripts•Get keys out of pocket•Put key in door•Open door•Get in car•Close door•Put key in ignition•Turn key to start car8Behavioral State Systems•Finite state machines–give them enough states to be interesting (each represents different goals or motives)–lots of inputs (environment attributes and other object states)•Some states may need substates or multi-part actions (e.g. move toward opponent and attack 20% of the time)•Personality of characters and spheres of influence may also be factored in as probabilistic input values to state entry or transitions9Memory and Learning •Memory is really just a decision to record a few details–record changes to frames–recording the last few moves•Learning is self-improvement–neural networks–genetic algorithms–numerical approaches (e.g. Samuels & checkers)–structural approaches10Deciding Between AI Techniques •Use deterministic techniques for simple behavior (e.g. rocks or missiles)•Add randomness and patterns for smart elements (e.g. birds or spaceships)•Use finite state machines for important game characters•For computer controlled opponents use everything (including memory and
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