Projectile Attack

breed [ clouds cloud ]
breed [ targets target ]
breed [ tanks tank ]
breed [ guns gun ]
breed [ shells shell ]


globals [ x-vel y-vel velocity previous-wall-height previous-wall-pos]

to setup
  clear-all
  set-default-shape tanks "tank"
  set-default-shape guns "gun"
  set-default-shape clouds "cloud"
  set-default-shape shells "ball"

  ask patches [ set pcolor 97 ]
  ask patches with [ pycor < -15 ]
    [ set pcolor black ]
  ; next we create the tank, it's gun, and the aiming arrow
  create-tanks 1
  [
    set heading angle
    setxy -16 -14.2
    set color green - 2
    set size 3
    hatch-guns 1 ; the tank's gun/nozzle
    [
      set size 1
      set color green - 3
      ; this confusing line of code creates a directed "tie" link
      ; between the tank and its gun
      ask myself [ create-link-to myself  [ tie hide-link ]]

      hatch 1 ; the "aiming arrow"
      [
        set breed turtles
        fd 3
        set color red - 1
        ; and now we create a directed "tie" link between
        ; the gun and its aiming arrow
        ask myself [ create-link-to myself [ tie hide-link ]]
      ]
    ]
  ]
  create-clouds 1
  [
    set shape "cloud"
    setxy 0 15
    set color 8
    set size 3.5
    set heading 90
  ]
  create-targets 1
  [
    set color black
    set shape "heli"
    setxy 15 (random 32) - 15
    set size 2
  ]

  ; create the wall
  ask patches with [ pycor > -16 ]
  [
    ifelse (pycor < wall-height - 15 and pxcor = wall-position )
      [ set pcolor gray ]
      [ set pcolor 97 ]
  ]
  set previous-wall-height wall-height
  set previous-wall-pos wall-position
end 

to go
  if not any? targets [ stop ]

  ask tanks [ set heading angle ]

  if ( previous-wall-height != wall-height or previous-wall-pos != wall-position )
  [
    ask patches with [ pycor > -16 ]
    [ ifelse (pycor < wall-height - 15 and pxcor = wall-position )
        [ set pcolor gray ]
        [ set pcolor 97 ]
    ]
    set previous-wall-height wall-height
    set previous-wall-pos wall-position
  ]
  every .05
  [
    ask shells
    [
      setxy (xcor + x-vel) (ycor + y-vel)
      set y-vel (y-vel - .01)
      ; NOTE: this is *NOT* modeling a realistic wind effect on a projectile.
      ; Instead, we just treat wind like gravitational acceleration along x-axis
      if (wall-block-wind? = false or
         (wall-block-wind? = true and (ycor > wall-height - 15) or ((xcor - wall-position) * wind < 0)))
        [ set x-vel (x-vel + (wind / 10000)) ]
      set velocity sqrt (( x-vel ^ 2 ) + (y-vel ^ 2))
      if (velocity > 1)
      [
        set x-vel x-vel / velocity
        set y-vel y-vel / velocity
        set velocity 1
      ]
      check-shell
    ]
    ask clouds [ setxy (xcor + wind / 100) (ycor) ]
  ]
  display
end 

to fire
  if not any? shells
  [
    ask tanks
    [
      hatch-shells 1
      [
        set size 1
        set color black
        set x-vel ( sin angle * ( Power / 100 ))
        set y-vel ( cos angle * ( Power / 100 ))
        set velocity Power / 100
      ]
    ]
  ]
end 

; This procedure uses a clever hack to simulate having no ceiling for the projectile
; Basically, if the projectile goes up above the ceiling, it actually wraps around,
; but it becomes hidden, until it comes back down again.  Obviously, this method
; isn't bulletproof, but it works pretty well for the purposes of this game.

to check-shell
  if ( pycor = -17 and hidden? = false )
      [ hide-turtle ]
  if ( pycor = 17 and hidden? = true )
      [ show-turtle ]
  if ( hidden? = false )
  [
     if ( xcor > 17 or ycor < -15 or pcolor = gray )
       [ die ]
     if ( any? targets-here )
       [
         ask patches in-radius 2 [ set pcolor yellow ]
         ask patches in-radius 1 [ set pcolor red ]
         ask targets-here [ die ]
         die
       ]
     set pcolor scale-color sky velocity 2 0
  ]
end 


; Copyright 2008 Uri Wilensky.
; See Info tab for full copyright and license.