myusernamejeep / impact-astar-for-entities

This plugin for the Impact Game Engine and added pathfinding to the entities. It also has a basic path following function, a example for path drawing function and a debug panel for showing the path of all entities.

Impact A* for Entities

Information

This plugin for the Impact Game Engine adds pathfinding to the entities. It also has a basic path following function, a example for path drawing function and a debug panel for showing the path of all entities.

Since version 1.0.0 it also can take entity types into his calculation. But it is only realy working for fixed obsticles.

Attention:

• The entities must be aligned with a tile and
• the size must be an multiple if the tilesize.

More information in the Impact Game Engine Forum: http://impactjs.com/forums/code/a-path-finder

It would be very nice when you inform me, with an short email, when you are using this plugin in a project.

Usage

Check the example/lib/game/main.js, example/lib/game/entities/player.js, example/lib/game/entities/enemy.js and example/lib/game/entities/enemy2.js!

getPath(destinationX, destinationY, diagonalMovement, entityTypesArray, ignoreEntityArray)

Calculates the path and the the result will be saved in this.path.

Since version 1.2.0 you also can activate the max movement with this.maxMovementActive. The lenght of the path can be modified with this.maxMovement. But you should deactivate the this.directionChangeMalus45degree and this.directionChangeMalus90degree maluses (Set them to zero ...) to prevent strange paths. Check the example/lib/game/entities/player.js for more information ...

• destinationX and destinationY: The destination ...
• diagonalMovement: If true diagonal movement is activated (Default) and when false it isn't.
• entityTypesArray: It is an array! It wants the entity type as string! Example: ['EntityPlayer', 'EntityEnemy', ...]
• ignoreEntityArray: Also an array! It wants references of the entities you want to exclude from the including into the collision map! Example: [this, enemey[0], ...]

followPath(speed, alignOnNearestTile)

Follows the calculated path. The current heading direction will be saved in this.headingDirection.

Heading direction values:

1 4 6
2 0 7
3 5 8

• speed: The velocity which will be used to follow the path.
• alignOnNearestTile: If activated (true) and the entity stops between tiles, it will automatically align on the nearest tile.

drawPath(r, g, b, a, lineWidth)

Draw the calculated path.

• r, g and b: The color of the path.
• a: Alpha value of the color.
• lineWidth: The width of the line ...

Live demo

Check out: http://www.hurik.de/impact-astar-for-entities/

Info

• The green player is controled by clicking on the maps. It can't go through the obstacles, except the one in the middle. Check the player.js how it works ...
• The red enemy follows the player. Every 2 seconds it calculates the path to the player. It cannot pass every obstacle. Check the enemy.js how it works ...
• The blue enemy follows the player. Every 4 seconds his path is updated. It can pass the obstacles and it cannot move diagonal. Check the enemy2.js how it works ...

Example

To change the level or work with the code, add in the example folder the missing libary files and folders:

lib/weltmeister/
lib/impact/
tools/
index.htmlw
weltmeister.html

Example images

TODO

• A* search algorithm (getPath)
  • Make it faster
  • Add coordinated movement (For the future ...)
  • More?
• path following (followPath)
  • Very much room for improvments ...
  • Make it more natural ...

Credits

Thanks to

• Joncom (Deactivate diagonal movement)
• FabienM (Heading Direction)
• docmarionum1 (Teleportation bug)
• tmfkmoney (Support for obsticles which are bigger than the tilesize)
• chadrickm (Max movement)

Based on

• https://gist.github.com/994534
• http://www.policyalmanac.org/games/aStarTutorial_de.html
• http://theory.stanford.edu/~amitp/GameProgramming/index.html

Changelog

v1.2.3

• A* search algorithm
  • Little bugfix with bigger entities
• General
  • Better example image

v1.2.2

• A* search algorithm
  • Little bugfix for the direction chnage maluses

v1.2.1

• A* search algorithm
  • Minor improvments
• General
  • Readme improved

v1.2.0

• A* search algorithm
  • Max movement (Thanks to chadrickm)
• General
  • Readme improved

v1.1.0

• A* search algorithm
  • Support for entities which are bigger than the tilesize, should be a multiple of the tilesize ... (Thanks to tmfkmoney)
• path following
  • Fix for teleportation bug (Thanks to docmarionum1)

v1.0.0

• A* search algorithm
  • Entity support
• General
  • Readme improved
  • Example highly improved

v0.9.4

• path following
  • alignOnNearestTile option was added: If the path was erased before the entity has gotten to his destination and stands between two tiles, this little check will adlign it on the nearest tile

v0.9.3

• A* search algorithm
  • If diagonal movement is deactivated, it uses the manhattan distance heuristic
• path following
  • Heading direction is now saved in the headingDirection variable, for more information check the example (Thanks to FabienM)

v0.9.2

• A* search algorithm
  • Now using the diagonal distance heuristic
  • Added seperate maluses for 45 degress an 90 degree direction changes, still testing for good values for the maluses
• General
  • Converted indentation to tabs

v0.9.1

• A* search algorithm
  • Now it is possible to deactivate diagonal movement (Example: getPath(destinationX, destinationY, false), default is true!) (Thanks to Joncom)
  • The check for not cutting edges was improved
  • Small G and H calculation changes

v0.9.0

• A* search algorithm
  • Added malus for direction change -> now nicer paths
• General
  • Added new example image to explain the direction change malus
  • Example demo updated the new code
  • Readme improved

v0.8.3

• A* search algorithm
  • Path now only saves the nodes, when the walking direction changed (Much less path points)
• path drawing
  • Because the new path save style, its now a line, like in the debug
• General
  • Example image changed

v0.8.2

• General
  • Example image changed
  • Readme improved

v0.8.1

• General
  • Little example demo update

v0.8.0

• General
  • Added example

v0.7.0

• A* search algorithm
  • Now calculates the real distances, working with even numbers wasn't faster
• path drawing
  • Basic function added, only as an example for a possible implematation

v0.6.0

• A* search algorithm
  • Checks now for walkable tiles and not for walls, no more problems with slopes anymore
• path following
  • Added entity movement stop when there is no path
  • No rounding anymore for diagonal movments speed calculation (Doesn't impact the framerate)

v0.5.2

• path following
  • followPath now really working, but still far from perfect ...

v0.5.1

• path following
  • followPath working for low framrates but FAR from a good implementation

v0.5.0

• General
  • Added version numbering
  • New example image
• A* search algorithm
  • The start tile of the entity is not anymore a part of the path
• path following
  • Added followPath(speed) function (Experimental at the moment, low framerates not working ...)
• Debug
  • Startpoint of the 'show paths' debug feature is now the middle of the entity