1 / 59

RTS Presentation

RTS Presentation. by Alex Dulmovits and Luis Villegas. History. History of RTS Games. History. Precursors to RTS Utopia (1982) Direct manipulation of unit and resources for combat Turn-based Legionnaire (1982) Real-time No resource or economy/production concepts. History.

tod
Download Presentation

RTS Presentation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. RTS Presentation by Alex Dulmovits and Luis Villegas

  2. History History of RTS Games

  3. History... Precursors to RTS • Utopia (1982) • Direct manipulation of unit and resources for combat • Turn-based • Legionnaire (1982) • Real-time • No resource or economy/production concepts

  4. History... First RTS Games • Dune II (1992)

  5. History... First RTS Games • Warcraft: Orcs & Humans (1994) • Command and Conquer • Age of Empires (1997) • Starcraft (1998)

  6. History... Transition to 3D and Refinement • Total Annihilation (1997) • 1st RTS with 3D elements

  7. History... Transition to 3D and Refinement • Empire Earth (2001) • Researching tech • Advancing Epochs

  8. History... Evolution of the RTS Formula • Sins of a Solar Empire (2008) • Grand-Scale stellar empire building

  9. History... Evolution of the RTS Formula • Achron • Time-travel elements

  10. History... Evolution of the RTS Formula • Halo Wars • Modern RTS on a console

  11. Architecting an RTS AI

  12. RTS Game Components • Civilization • Build • Unit • Resource • Research • Combat

  13. Game Components: Civilization Manager • Highest-level manager responsible for development of the computer player's economy • Responsible for coordination between the build, unit, resource and research managers • Responsible for spending limits • Computer player expansion, upgrading and epoch advancement (EE)

  14. Game Components: Build Manager • Responsible for placement of structures and towns • Receives requests from the unit manager for training buildings • Receives requests from the civilization manager for support buildings • All site evaluation occurs here

  15. Game Components: Build Manager • Where buildings can and cannot be placed • RTS games restrict component placement • Red usually signifies invalid placement

  16. Game Components: Build Manager • Take "area of effect" buildings into account • Buildings with an area of effect are placed near resources, where most units are likely to congregate

  17. Game Components: Build Manager • Military Buildings • Nearby resources, but shouldn't interfere with area of effect buildings • Built in a ring around immediate area of resources • Other Buildings • Farms, airports, walls, docks, towers require specialized placements • Depends on terrain analysis engine • Place towers in choke points, avoid building near enemies

  18. Game Components: Unit Manager • Responsible for training units • Keeps track of what units are in training in various buildings • Monitors the computer player's population limits • Prioritizes unit training requests

  19. Game Components: Unit Manager • If training building not currently available, unit manager communicates with build manager • Attempts to maintain a similar unit count to the human players in the game to balance difficulty of game • By not allowing AI unit count to get too high, we lessen the CPU load of the game

  20. Game Components: Resource Manager • Responsible for tasking citizens to gather resources in response from both the unit and build managers. • Balances gathering duties • Governs the expansion of the computer player to newly explored resource sites

  21. Game Components: Research Manager • Responsible for directed research of computer player • Technologies are examined and selected based on their usefulness and cost

  22. Game Components: Combat Manager • Responsible for directing military units on the battlefield • Requests units to be trained via unit manager • Deploys units in whatever offensive or defensive position is most beneficial

  23. Game Components: Combat Manager • Keeps track of units via a personnel manager • Periodically updates the status, movement and actions of various attack groups • Offense and Defense are sub-managers within the combat manager.

  24. Game Components: Combat Manager • Depending on what programming language is used, the combat manager communicates with the other managers in different ways. • In C++, with the managers implemented as classes, public methods can be used as a means to communicate.

  25. Game Components: Combat Manager • Example: TrainUnit method in Empire Earth's Unit Manager • Responsible for for bringing new units into the world • Parameters: unit type, number desired, where is the unit required? (optional) • Communicates with Resource Manager to ensure sufficient resources, checks population headroom, communicates with Build Manager if training building needed

  26. Game Components: Combat Manager • Example: TrainUnit method in Empire Earth's Unit Manager • Use training orders as a mechanism to determine when the request was complete • Training Orders are simple classes that contain information about the request and a method to call to check if and when something is complete

  27. Game Components: Combat Manager • RTS Combat AI Example • Shogun 2

  28. Game Components • All the game components will be communicating with each other • The problem comes when changing a manager • Small changes have profound effects on AI • AI becomes unpredicatable • Tracking down chains of cause and effect becomes the focus of late development testing

  29. Difficulty Levels

  30. The Difficult Problem of Difficulty • Games are played by players with a broad range of experience • Tailor games to fit level of competence of player • Need to find a way for AI that can learn from the player as it goes along • Settle for pre-set difficulty levels • Avoid just adding more computer players for expert players. (more work for player and CPU)

  31. The Difficult Problem of Difficulty • Goal should be to develop an AI that is good enough to give challenge to an expert player in a 1-to-1 match • Then tone down AI for intermediate and beginners • Hire expert players to help programmers do balancing • More difficult to start with an easy AI and increase its intelligence

  32. The Difficult Problem of Difficulty • Choose what modifications to make to differentiate difficulty levels (narrow down) • The more variables you have, the harder it will be to test changes • Testing difficulty level changes is very time-consuming • Consider Cheating • Biggest Challenge: random maps

  33. Priorities in Goal-Based RTS AI

  34. Goal Engine Architecture • Responsible for making all strategic-level decisions in the opposing player AI • Decides what actions to take, where to take those actions, and what resources to apply to each

  35. Actors • Things within the game controlled by a human or AI players • Buildings: immobile actors • Defensive structures: can attack things • Economic buildings: provide some nonmilitary advantage • Units: movable actors • Military Units: can attack things • Builders: construct and/or repair buildings Combat Value (CV): numerical measure of an actor's effectiveness in a fight

  36. Goals • Used to represent every action a player can take in the game • attack, defend, explore, recruit, construct, and repair • Influenced by resources (units, money) • Goal status: active/inactive/selected/finished • Base priority: priority of certain goal given the current state • Current priority: takes into account resource assignments as well as game state Change of priority by red team: http://youtu.be/0b1uSwY48r0?t=3m23s

  37. Generating Goal Priorities (Part 1) • Common Tools: balance varying factors going into a priority • Make more realistic/human- like • Less predictable • Multipliers • Exponents • Min. values • Max. values • Inversion • Bonuses • One-time Bonuses • Repeat penalties • Random Bonuses • Fuzzy Factor: random bonus added to base priority of every goal • Goal Inertia: any bonus added to goals selected previously • Goal Commitment: even though requirements might not be met at the moment, still selected

  38. Generating Goal Priorities (Part 2) • Money Value: AI needs to understand the value of resources such as: gold, wood, iron, food • How much? - More needed? • Actor Value: the value of an actor plays a large role in the priority of a goal • Some considerations that affect the determination of the actor priority • effect an actor has on the economy • the combat value of an actor • the strategic value of the actor's position • the location in the AI's territory

  39. Generating Goal Priorities (Part 3) • Build Template: where buildings should be built with respect to one another • Bonuses for building certain buildings close to one another • Map Analysis: spatial reasoning • Region: map split up into rectangles where units can move freely • Pathfinding: using pathfinding system, can calculate distance between points which will encourage units to move to closer goals • Military Influence: every actor adds an influence to the region they are in depending on their CV • Equation:

  40. Attack Goal • Attack goals are directed at an entire region • Base priority takes into account: • maximum number of a player's CV in a certain region • value that any capturable enemy actors would provide if they were controlled • Current priority takes into account: • CV ratio (ratio of friendly CV to hostile CV) • value of friendly CV in neighboring regions • whether or not there are known hostile units along path to attack region

  41. Goal Based AI Conclusion • Advantages • Flexible and powerful • Complexity scales fairly well as AI grows • Can execute more than one goal at a time • Emergent behavior (to an extent) • Disadvantages: • Priority calculations (“Bucket of Floats”) • Emergent behavior (becomes predictable)

  42. RTS Citizen AI

  43. Citizens • Responsible for the building and gathering of resources within a town • Usually low CV • Problem: • Citizens can be instructed by player on what to do • But after completing their task what do they do? • Solution: • AI uses build and gather goals to instruct when/where to build and gather resources

  44. Goals • A player can give citizens high-level goals • A citizen accomplishes these goals by following an FSM of varying actions • Citizens will continue their cycle of actions until sent a trigger by the player which will cause them to move onto another action

  45. Building and Repairing • When a player selects to create a building with certain citizens, the citizens must: • Establish a build site (location where the citizen is to position themselves in order to build the building) • Find a path to the build site • Begin to build the building (by gradually adding hit points to it) • Once the building is complete, the citizen goes idle and waits for next trigger from the player • For repairs: • Similar to building, except the building location has already been determined • Each hit point repaired to the building, cost the player resources • If the player runs out of resources, the citizen goes idle

  46. Building and Repairing • Build Site Selection: • must find a location around the desired building • must take other citizens' build sites into account before determining theirs • Citizen Build Queues • player can issue a queue of commands to a citizen • additional commands are added onto the back of the queue • Three-Phase Building Construction • Foundation: - must be cleared before construction begins - when in construction does not block paths • Scaffolding: - stage during construction - becomes visible to other players in range - more citizens working, the faster it is built • Completed

  47. Gathering • Citizens must gather resources from a resource unit (gold ore, trees, etc.) and bring to a storage unit (town center, mill, etc.): • A player gives selected citizens a command to gather a certain resource • Citizens pathfind to the resource • They gather until their capacity is reached • Then they locate the nearest storage unit and dump the resources off adding to the player's total • Repeat • If a citizen can't find a resource unit or storage unit, it will become idle

  48. Citizen AI Example: Empire Earth http://youtu.be/GUWnK25BdJE?t=2m30s

  49. RTS Terrain Analysis

  50. RTS Terrain Analysis • First need to know information about the terrain to determine what tactic the AI should perform • Some questions that can be used to determine terrain information: • Are my troops in a single region? • Are there enemy forces in the same region as my troops? • Does my region have connections to others? • What regions have important strategic value?

More Related