---

Lua for GuildEd Engine

GuildEd is a 2D game engine made by the faculty at The Guildhall, SMU. The faculty was generous enough to allow me the opportunity to program elements to be implemented into the final product.

Ravish Nair (http://www.ravishnair.com) and I collaborated in an effort to code the AI pathnode element in GuildEd. Pathnodes are used to move actors from one point to the other. When actors collide with a pathnode, they look for the next assigned pathnode and move towards it.

---

Code in Action

---

Code Excerpt

    
    --[[  
    Function Name   : EnemyPathnodeUpdate()  
    Arguments       : o  
    Description     : Checks position of Enemy and looks for the next assigned pathnode.  
                      Sets direction of enemy movement towards next pathnode.  
                      Repeats.  
    Created by      : Corey McKemy and Ravish Nair, 04/26/2012  
    Last Updated by : Corey McKemy and Ravish Nair, 05/09/2012 : Initial version  
    Notes           : Created so that enemy paths can be controlled and avoid falling to their death.  
    --]]  
      
    priority = -899  
      
      
      
    ui = {  
        isFirst      = { type = "bool",    label = "Enemy active at level start", default = true },  
        name         = { type = "string",   label = "Name"},  
        nextName     = { type = "string",   label = "Next Name"},  
    }  
      
    --CM and RN: Initializes and stores pathnode name, name of the next pathnode, and position into a global table: g.pathNodeTable  
    function init()  
        path = {name = nil, nextName = nil, positionX = nil, positionY = nil}  
        temp = {}  
        me = ActorBase()  
        --CM and RN: Set collision to be a sensor.  
        me.collision.SetCollision( x, y, iconW/pixelsPerUnit, iconH/pixelsPerUnit, "Box", RigidBody_SENSOR )  
        rigidBody:setCollisionCategory( 2 )  
        me.name = name  
        me.nextName = nextName  
         
        positionX = rigidBody:posX()  
        positionY = rigidBody:posY()  
      
        path.name = name  
        path.nextName = nextName  
        path.positionX = positionX  
        path.positionY = positionY  
        g.table.insert( g.pathNodeTable, path )  
    end  
      
    function update( dt )  
    end  
      
    --CM and RN: Updates enemy direction based on the next pathnode.  
    function EnemyPathnodeUpdate( o )  
        if (name == o.currentNode.name)then  
          for jj = 1, g.table.getn( g.pathNodeTable ) do  
              if g.pathNodeTable[jj].name == nextName then  
                  --CM and RN: Updates the current pathnode  
                  o.currentNode = g.pathNodeTable[jj]  
                  --CM and RN: Sends enemy to the direction of the new current pathnode  
                  if g.pathNodeTable[jj].positionX > o.rigidBody:posX() + (( iconW/pixelsPerUnit )/2)  then  
                      o.speed = g.math.abs(o.speed)  
                  else  
                      o.speed = -1 * (g.math.abs(o.speed))  
                  end  
              end  
          end  
        end  
    end  
      
    --RN: Updates enemy direction based on the next pathnode.  
    function PlatformPathnodeUpdate( o )  
        if (name == o.PlatformCurrentNode.name)then  
          for jj = 1, g.table.getn( g.pathNodeTable ) do  
              if g.pathNodeTable[jj].name == nextName then  
                  --CM and RN: Updates the current pathnode  
                  o.PlatformCurrentNode = g.pathNodeTable[jj]  
                  --CM and RN: Sends enemy to the direction of the new current pathnode  
                  if g.pathNodeTable[jj].positionX > o.rigidBody:posX() + (( iconW/pixelsPerUnit )/2)  then  
                      o.MoveSpeedX = g.math.abs(o.MoveSpeedX)  
                  else  
                      o.MoveSpeedX = -1 * (g.math.abs(o.MoveSpeedX))  
                  end  
              end  
          end  
        end  
    end  
      
      
      
    --CM and RN: Checks to see object of collision.  
    function beginContact( o )  
        if ( o:isType("Enemy1") ) then  
           EnemyPathnodeUpdate( o )  
        end  
         
        if ( o:isType("MovingPlatform") ) then  
            PlatformPathnodeUpdate( o )  
        end  
    end  

---