Box Drawing Example

;; declare a global variable, halfedge, to be used when the box center is at (0,0)

globals [halfedge]

;; setup procedure for case where point (0,0) is lower left corner of Box
;;note slider that sets the size of the box.

to setup-corner
  ca                                              ;; clear everything
  ask patches[
    ;; if patches are between (0,0) to (0,edge)...
    if ( pxcor = 0 and pycor >= 0 and pycor <= edge )
      [set pcolor red]                                 ;; ... draws left edge in red
    ;; if patches are between (edge,0) to (edge,edge)...
    if ( pxcor = edge and pycor >= 0 and pycor <= edge )
      [set pcolor red]                                 ;; ... draws right edge in red
    ;; if patches are between (0,0) to (edge,0)...
    if ( pycor = 0 and pxcor >= 0 and pxcor <= edge )
      [set pcolor red]                                 ;; ... draws bottom edge in red
    ;; if patches are between (0,edge) to (edge,edge)...
    if ( pycor = edge and pxcor >= 0 and pxcor <= edge )
      [set pcolor red]                                 ;; ... draws upper edge in red
    ]
end 


;; setup procedure for case where point (0,0) is in the center of Box

to setup-center
  ca                                              ;; clear everything
  ;; set halfedge as edge divided by two. in case edge is an odd number,
  ;; halfedge get the integer value of the division.
  set halfedge int (edge / 2)
  ask patches[
    ;; if patches are between (-halfedge,-halfedge) to (-halfedge,halfedge)...
    if (pxcor = (- halfedge) and pycor >= (- halfedge) and pycor <= (0 + halfedge) )
      [set pcolor blue]                                ;; ... draws left edge in blue
    ;; if patches are between (halfedge,-halfedge) to (halfedge,halfedge)...
    if ( pxcor = (0 + halfedge) and pycor >= (- halfedge) and pycor <= (0 + halfedge) )
      [set pcolor blue]                                ;; ... draws right edge in blue
    ;; if patches are between (-halfedge,-halfedge) to (halfedge,-halfedge)...
    if ( pycor = (- halfedge) and pxcor >= (- halfedge) and pxcor <= (0 + halfedge) )
      [set pcolor blue]                                ;; ... draws bottom edge in blue
    ;; if patches are between (-halfedge,halfedge) to (halfedge,halfedge)...
    if ( pycor = (0 + halfedge) and pxcor >= (- halfedge) and pxcor <= (0 + halfedge) )
      [set pcolor blue]                                ;; ... draws upper edge in blue
    ]
end 


; Public Domain:
; To the extent possible under law, Uri Wilensky has waived all
; copyright and related or neighboring rights to this model.