Create Enemy Path / AI

Monkey Forums/Monkey Programming/Create Enemy Path / AI

Monking (Posted 2013) [#1]

I'm new to Monkey Programming so by now I've no idea what to start with. I read the book and get the simple knowledge. But now, I wish to study my first game, simplest one, maze like Pacman. Well, I face the problem of creating enemy. There are two type of enemy, first is move with path, eg: this enemy is move from position 0,0 to 128,0 then move back and vice versa The second enermy could be A.I, like finding a way to go..and when meet player..he will chase it..some sort of that.. I'm using fantomEngine..is that fantomEngine can do some sort like this.. as I tried to create 2 classes, like for example Class game Extends App and another Class Enermy.. it would not draw out the image.. so I was running out of idea.. Any Relevant example ?? Example codes is preferable, Thank You.

dawlane (Posted 2013) [#2]

Well I haven't the time to post any code but GameInternals should give you some ideas as it's what they did with pacman. My advice to anyone new to Monkey ( or any programming language ) is not to use any engine until you can write some code of your own as it can take some understanding when things go wrong and make it had for anyone who hasn't got said engine to help out.. An object that moves back and forth is one of the easiest things to do. You have a direction value that you flip when your object have reached it's objective. give x a start position say 400 give d a direction as -5 in a loop if x < 200 Or x > 600 Then d = -d x+=d Problem you will find with this approach is when you try and go diagonally. Then your better off using vectors. Have a look on google there should be plenty of tutorials out the for sprite movement that can be easily adapted to work with monkey. Check out these Invader Jim tutorials.

Why0Why (Posted 2013) [#3]

Definitely watch the excellent tutorial videos by Invader Jim: http://www.monkeycoder.co.nz/Community/posts.php?topic=3318

MikeHart (Posted 2013) [#4]

fantomEngine supports something like a pacman game definately very well with its path finding methods and the waypoints. If you want to create own classes for each different object, you can do this with customclasses (user defined classes) which extend ftObject. There is already an example shipping with fE that shows how to use a cusotm class but I will upload a multiclass example soon too.

MikeHart (Posted 2013) [#5]

And please post the code you have so me or someone else can try to help you.

MikeHart (Posted 2013) [#6]

Here is an example with multiple classes and custom objects: http://www.fantomgl.com/?p=521

Supertino (Posted 2013) [#7]

Fantastic A* *path finding) tutorial here http://www.policyalmanac.org/games/aStarTutorial.htm very useful for maze/pacman games - if you can't follow this you'll struggle with AI.

Monking (Posted 2013) [#8]

Thank you for everyone comments, I guess I've more to learn.. By the way, respond to MikeHart, I should upload my demo coding..here: https://www.dropbox.com/s/9gbr65kazvyllk2/First_Maze.zip I'm using the latest fantomEngine from here: http://code.google.com/p/fantomengine/ Well, before viewing the coding of this demo.. I suggest anyone who downloaded has some preparation to view this horrible coding.. Well, maybe dawlane is right.. I should learn the basic instead of using any engine.. I know my coding and programming skill is horrible, so I can accept any suggestion. Any suggestion is appreciated. Thank you very much.

dawlane (Posted 2013) [#9]

One suggestion I would make is modularise your code as it does three things 1) Makes it easier to read 2) Easier to mantain 3) Easier to debug. And always use Strict Try and keep your game enemies, players, maze/levels, etc as separate classes from your main Game class. All your main game class needs to do is control when to do what.

dawlane (Posted 2013) [#10]

And another thing learn about functions methods and return types Something that wont work but should give you some ideas. Can't give a proper example as I'm on a machine that has got monkey installed. In One file called sprites.monkey Strict Import mojo Class CSprite Global sprite_list:= New List<CSprite> Field x:Int Field y:Int Field image:Image Method New( x:Int = 0, y:Int = 0 ) ' = makes sure that the constructor has values Self.x = x Self.y = y End Method Function CreateSprite:Void( x:Int, y:Int, image:Image ) Local sp:CSprite = New CSprite( x, y ) sp.image = image sprite_list.AddLast(sp) End Function Function CreateSprite:CSprite( x:Int, y:Int, image:Image ) Local sp:CSprite = New CSprite( x, y ) sp.image = image Return sp End Function Function Update:Int() ' Do Some Code 'Call a Method ' If task didn't go as planed then exit with a error or whatever If Not Self.Task() Then Return 1 Return 0 End Function Method Task:bool() 'Do some checking code Return False if failed Return True End Method Method DrawSprite:Void() 'Draw a sprite End Method Function DrawSprites:Void() For Local i:CSprite= EachIn sprite_list i.DrawSprite() Next End Function End Class In monkeygame.monkey Strict Import mojo Import sprites Class Game Extends App Field sp:CSprite Method OnCreate:Int() sp = CSprite.Creat( 20, 20, sprite_image ) ' Return a sprite CSprite.Create( 20, 20, sprite_image ) ' Add a sprite to the sprite list Return 0 End Method Method OnUpdate:Int() If CSprite.Update > 0 'Do Some Code EndIf Return 0 End Method Method OnRender:Int() Self.sp.DrawSprite() CSprite.DrawSprites() Return 0 End Method End Class

mteo77 (Posted 2013) [#11]

Hello. Here there some code for a simple "follow path" movement type. The path is stored in an array that you can modify (just change the values!). It has some simple object structures and object creation, also it will react to user input to change speed and curve approximation. It has some math but hopefully you will understand it. I don't use strict mode yet, and it's pretty well explained (hopefully). This can be the basis for a simple AI, it's not a pathfinding routine but its a start! #rem simple waypoint movement, 10/4/2013 #end Import mojo Global max_path_points:int = 20 Global pathx:Int[max_path_points] ' set up 20 path points Global pathy:Int[max_path_points] ' -1 because arrays start at zero Global Gspeed:Float Global CSmoothness:Int Function Main() New Game End Function Class Game Extends App Field movement_started:Bool Method OnCreate() CSmoothness = 3 Gspeed = 4 movement_started = False arrayFilling() SetUpdateRate(60) End Method Method OnRender() Cls DrawText "Waypoints player....for testing enemy movements!Space to start, enter to stop!", 0, 0 DrawText "Pressing the right mouse button will create objects!", 0, 20 DrawText "Press up&down arrows keys To increase/decrease speed", 0, 30 DrawText "Press right&left arrow keys to increase/decrease curve approximation", 0, 40 DrawText "Speed: " + Gspeed, 320, 60 DrawText "Curve smoothness: " + CSmoothness, 400, 60 draw_path_points() enemy.RenderAll() End Method Method OnUpdate() If MouseHit(1) enemy.CreateEnemy(pathx[0], pathy[0]) EndIf If KeyHit(KEY_UP) Then Gspeed = Gspeed + 1 If KeyHit(KEY_DOWN) Then Gspeed = Gspeed - 1 If KeyHit(KEY_LEFT) Then CSmoothness = CSmoothness - 1 If KeyHit(KEY_RIGHT) Then CSmoothness = CSmoothness + 1 If KeyHit(KEY_1) Then enemy.CreateEnemy(pathx[0], pathy[0]) If KeyHit(KEY_SPACE) And movement_started = False Then 'space bar start the movement movement_started = True 'set flag for movement started End If If KeyHit(KEY_ENTER) Then 'enter stop the movement movement_started = False 'clear flag for movement End If If movement_started = True Then enemy.UpdateAll() 'start updating the object position End Method End Class Class actor Field nextx:Float 'next x position Field nexty:Float 'next y position Field posx:Float 'x coord Field posy:Float 'y coord Field speed:float 'speed Const Lbound:Int=0 'left boundary Const Rbound:Int = 640 'right boundary Const Ubound:Int=0 'up boundary Const Dbound:Int=480 'down boundary End Class Class enemy Extends actor Global nemico:= New List<enemy> 'list that holds all enemy instances Field curveSmoothness:Int 'the curve approxximation smoothness Field ANGLE:Float 'used to check for position Field dist:Float 'distance between current and next coords Field ang:Float 'used to check for path points Field current_path:Int 'current path node pointer Method init(x:Float, y:Float) current_path = 0 curveSmoothness = CSmoothness posx = x 'x position is equal from start position,otherwise everything will start at 0 posy = y 'same as above nextx = pathx[current_path] nexty = pathy[current_path] speed = Gspeed End Method Method update() curveSmoothness = CSmoothness 'we have to check the curve smoothness for every update speed = Gspeed 'same for speed If current_path = max_path_points - 1 'when the path reaches the max path current_path = 0 'this repeat the movement by resetting the node to the first one nextx = pathx[current_path] 'these lines set the target path to the first one nexty = pathy[current_path] 'same as above EndIf If current_path < max_path_points - 1 'if target path is less than maximum ang = ATan2(pathy[current_path + 1] - pathy[current_path], pathx[current_path + 1] - pathx[current_path]) 'arc tangent of the distance between current and next nodes nextx = nextx + Cos(ang) * speed 'update target x pos based on speed nexty = nexty + Sin(ang) * speed 'update target y pos based on speed If Abs(nextx - pathx[current_path + 1]) < 15 And Abs(nexty - pathy[current_path + 1]) < 15 'when the absolute value of the 2 points is less than 15 current_path = current_path + 1 'the current path become the next one nextx = pathx[current_path] 'the target pos become the current node nexty = pathy[current_path] 'same as above EndIf EndIf ANGLE = ATan2(nexty - posy, nextx - posx) 'arc tangent of the distance between target node and current position dist = Sqrt( (posx - nextx) * (posx - nextx) + (posy - nexty) * (posy - nexty)) 'dist is the square root of the difference between position and target node posx = posx + (Cos(ANGLE) / curveSmoothness) * (dist / curveSmoothness) 'update posx based on smoothness posy = posy + (Sin(ANGLE) / curveSmoothness) * (dist / curveSmoothness) 'update posy based on smoothness End Method Method render() DrawCircle posx, posy, 20 'draw the object End Method Function CreateEnemy(x, y) Local n:enemy = New enemy() n.init(x, y) nemico.AddLast(n) End Function Function UpdateAll() For Local n:= EachIn nemico n.update() Next End Function Function RenderAll() For Local n:= EachIn nemico n.render() Next End Function End Class Function draw_path_points() Local loop For loop = 0 To max_path_points - 1 'loop through all the path points DrawRect pathx[loop], pathy[loop], 2, 2 If loop < max_path_points - 1 Then 'do this loop while the loop value is less than the highest path value DrawRect pathx[loop + 1] - 1, pathy[loop + 1] - 1, 2, 2 'draw a rectangle at the path point so its central DrawLine pathx[loop], pathy[loop], pathx[loop + 1], pathy[loop + 1] 'draw a line between the current point and the next one End If Next End Function Function arrayFilling() pathx[0] = 31 pathy[0] = 54 pathx[1] = 82 pathy[1] = 127 pathx[2] = 171 pathy[2] = 145 pathx[3] = 294 pathy[3] = 138 pathx[4] = 362 pathy[4] = 163 pathx[5] = 420 pathy[5] = 221 pathx[6] = 425 pathy[6] = 295 pathx[7] = 388 pathy[7] = 311 pathx[8] = 330 pathy[8] = 274 pathx[9] = 316 pathy[9] = 219 pathx[10] = 338 pathy[10] = 176 pathx[11] = 401 pathy[11] = 112 pathx[12] = 271 pathy[12] = 59 pathx[13] = 191 pathy[13] = 91 pathx[14] = 133 pathy[14] = 187 pathx[15] = 136 pathy[15] = 276 pathx[16] = 58 pathy[16] = 316 pathx[17] = 33 pathy[17] = 229 pathx[18] = 13 pathy[18] = 119 pathx[19] = 12 pathy[19] = 76 End Function Function round:Int(_value:Float) 'it rounds a variable to the nearest integer (ex:1.3 to 1) Return _value + (Sgn(_value) * 0.5) End Function

mteo77 (Posted 2013) [#12]

Sorry for my english but i am tired and ready to hit the sack...

Monking (Posted 2013) [#13]

Okay thanks, I try my best.

Gerry Quinn (Posted 2013) [#14]

When doing AI it's easiest to start with a really simple one (e.g. never change direction and turn at random at any corner). Then you can ensure that everything is working before slotting in more elaborate ones.