Desert of the Real

Table of Contents
Figure 1: Title screen

Entry for the Merveilles HyperCard jam.


The name of the game comes from Jean Baudrillard's book “Simulacra and Simulation”.

Today abstraction is no longer that of the map, the double, the mirror, or the concept.

Simulation is no longer that of a territory, a referential being, or a substance. It is the generation by models of a real without origin or reality: a hyperreal.

The territory no longer precedes the map, nor does it survive it. It is nevertheless the map that precedes the territory - precession of simulacra - that engenders the territory, and if one must return to the fable, today it is the territory whose shreds slowly rot across the extent of the map.

It is the real, and not the map, whose vestiges persist here and there in the deserts that are no longer those of the Empire, but ours. The desert of the real itself.

One theme of the book is how reality has been reduced to (and can be reproduced from) integrated circuits, the simplified languages of computer science, genetic codes.

This reminded me of how Quadtree Grammars can produce intricate structures from a set of simple rules.

No more imaginary coextensivity: it is genetic miniaturization that is the dimension of simulation. The real is produced from miniaturized cells, matrices, and memory banks, models of control - and it can be reproduced an indefinite number of times from these.

To contrast the clean shapes of the generated structures, everything else is drawn using the spray can tool, which fits nicely into the desert theme.

The player enters the desert of the real, encounters multiple structures reduced to (or reproduced from) simple rule systems, and upon reaching the final pyramid, unlocks the editor that allows them to view and modify the rules behind each of the structures.


Figure 2: Telescope in the desert
Figure 3: Looking through the telescope
Figure 4: Quadtree editor

Annotated Source Code

Each stack in HyperCard can have multiple backgrounds and each background can have multiple cards.

Backgrounds and cards can contain text fields, buttons and pictures (black / white / transparent).

In my stack, almost every card has its own background, used to draw the quadtree structures, with everything else drawn in the foreground.

I wanted to have a way of editing a card's background without switching to a special editor card, regenerating the quadtrees, then copying the results back to the original card.

To allow me to still change the editor interface without having to update all card backgrounds, I decided to build the whole editor interface without using any fields or buttons, just by drawing rectangles and using the text tool (which draws its text directly in the card / background picture).

The editor logic is placed in the stack script (shared between all cards and backgrounds) with a on mouseUp handler and a global variable to keep track of whether the editor is open or not ( gOpen ).

This way, editing the ruleset for a card's background is as simple as setting gOpen to true , then switching to the card's background.

on editBg
  global gOpen
  put true into gOpen
  doMenu "background"
  setMinSize 8
end editBg

on quitBg
  global gOpen
  doMenu "background"
  put false into gOpen
end quitBg

On opening a card, gOpen is set to false to deactivate the editors click handler.

on openCard
  global gOpen
  put false into gOpen
end openCard

To determine if an element of a rule is a pattern or a reference to another rule, we need to check if it is a number. For performance reasons, only the first character is checked.

function isDigit s
  return offset(s, "0123456789") is not 0
end isDigit

function isNumber s
  return  isDigit(char 1 of s)
end isNumber

One interesting feature of HyperCard is that there are no special functions for drawing shapes or text. Instead, you have to choose the correct tool, then call draw from pos1 to pos2 to simulate clicking on the screen and dragging the mouse, e.g. to draw a rectangle.

Because switching tools is slow, there are two functions for drawing rectangles, one that switches tools first and one that assumes the rect tool is active ( drawRectF ).

Both handlers take an origin point ox,oy , a size sx,sy and a fill-pattern p as arguments.

on drawRectF ox,oy,sx,sy,p
  if p is not 0 then
    set filled to true
    set pattern to p
    drag from ox,oy to (ox+sx),(oy+sy)
  end if
end drawRectF

on drawRect ox,oy,sx,sy,p
  choose rect tool
  drawRectF ox,oy,sx,sy,p
  choose browse tool
end drawRect

Text is drawn the same way, this time using the text tool and type to simulate entering the text using the keyboard.

on drawText x,y,t
  choose text tool
  click at x,y
  type t
  choose browse tool
end drawText

Fields in the rule editor are either filled with one of the 40 patterns or with a letter "0", "A".."H" for each of the eight rules.

drawField is called with a position x,y and a pattern / rule name p .

The patterns are named 1 to 40 , so we can check whether p is a number, then draw either a filled square or a text field.

on drawField x,y,p
  if isNumber(p) and p > 0 then
    put (x * 16) into x
    put (y * 16) + 256 into y
    drawRect x,y,16,16,p
    drawTextField x,y,1,p
  end if
end drawField

on drawTextField x,y,w,p
  put (x * 16) into x
  put (y * 16) + 256 into y
  drawRect x,y,16*w,16,1
  drawText (x+4),(y+13),p
end drawTextField

Next, we need to draw each element of the quadtree editor.

on drawMenu
  global gOpen
  put false into gOpen
  selectPattern 0
  put true into gOpen
end drawMenu

on selectPattern p
  global gPattern
  put p into gPattern
  drawField 16,1,p
end selectPattern

on drawPatternMenu1
  drawField 17,1,"A"
  drawField 17,2,"B"
  drawField 17,3,"C"
  drawField 17,4,"D"
  drawField 18,1,"E"
  drawField 18,2,"F"
  drawField 18,3,"G"
  drawField 18,4,"H"
  drawField 19,1,"0"
end drawPatternMenu1

on drawPatternMenu2
  repeat with x = 0 to 9
    repeat with y = 0 to 3
      put 1+x+(y*10) into p
      put x*16+256+64 into xx
      put y*16+256+16 into yy
      drawRect xx,yy,16,16,p
    end repeat
  end repeat
end drawPatternMenu2

on drawMainMenu
  drawTextField 0,1,1,"-"
  drawTextField 3,1,1,"+"
  setMinSize 8
  drawTextField 4,1,4,"Draw"
  drawTextField 8,1,4,"Quit"
  drawTextField 12,1,4,"Reset"
end drawMainMenu

Rules are stored in a hidden background field, with one rule on each line. Each line has the form A -> A 12 A A or 1 (name of the rule -> the four elements it expands to or fallback pattern).

on drawRuleMenu
  repeat with x = 0 to 7
    put word 8 of line x + 1 of background fld rules into p
    drawField x*2+1,2,p
    drawTextField x*2,2,1,numtochar(x + 65)
  end repeat
  repeat with x = 0 to 15
    repeat with y = 0 to 1
      put 1 + (x div 2) into r
      put word (x mod 2) + 3 + 2*y of line r of background fld rules into p
      drawField x,y+3,p
    end repeat
  end repeat
end drawRuleMenu

on setRule l,w
  global gPattern
  put gPattern into word w of line l of background field "rules"
end setRule

Each time the mouse is clicked, we check if the editor is open, then pass the click location to handleClick .

on mouseUp
  global gOpen
  if gOpen then
    put the clickH into x
    put the clickV into y
    handleClick x,y
  end if
end mouseUp

handleClick is just a big if~/~else that checks which of the elements has been clicked and calls the handler for it.

A neat trick here is the use of numToChar to translate click positions into the characters "A" to "H".

on handleClick x,y
  global gMinSize, gPattern
  if y >= 256 then
    put x div 16 into x
    subtract 256 from y
    put y div 16 into y
    if x < 16 then
      if y = 1 then
        if x = 0 then setMinSize gMinSize div 2
        else if x = 3 then setMinSize gMinSize * 2
        else if x > 3 and x < 8 then drawRules
        else if x > 8 and x < 12 then quitBg
        else if x > 12 and x < 16 then resetRules
      end if

      put 1+(x div 2) into r
      if y = 2 then
        if x mod 2 = 1 then
          drawField x,y,gPattern
          setRule r,8
        end if
      else if y = 3 or y = 4 then
        drawField x,y,gPattern
        setRule r,2+(1+(x mod 2)+(y-3)*2)
      end if
    end if

    if x = 17 and y >= 1 then
      selectPattern numToChar(64+y)
    end if
    if x = 18 and y >= 1 then
      selectPattern numToChar(68+y)
    end if
    if x = 19 and y = 1 then
      selectPattern 0
    end if

    -- Pattern Selector
    if x >= 20 and y >= 1 then
      subtract 20 from x
      subtract 1 from y
      selectPattern 1 + x + (y * 10)
    end if
  end if
end handleClick

getRule does the reverse, using chartonum to translate a character "A".."H" into a line number from 1 to 8.

function getRule n
  return line chartonum(n) - 64 of background field "rules"
end getRule

expandRule expands a rule element (pattern or rule reference) into a quadtree of size s at position ox,oy .

If the size is below gMinSize , the rules fallback pattern is used instead.

on expandRule rule,ox,oy,s
  global gMinSize
  if s > gMinSize then
    put s div 2 into h
    put word 3 of rule into w
    if isNumber(w) then
      drawRectF ox,oy,h,h,w
      expandRule getRule(w),ox,oy,h
    end if

    put word 4 of rule into w
    if isNumber(w) then
      drawRectF ox+h,oy,h,h,w
      expandRule getRule(w),ox+h,oy,h
    end if

    put word 5 of rule into w
    if isNumber(w) then
      drawRectF ox,oy+h,h,h,w
      expandRule getRule(w),ox,oy+h,h
    end if

    put word 6 of rule into w
    if isNumber(w) then
      drawRectF ox+h,oy+h,h,h,w
      expandRule getRule(w),ox+h,oy+h,h
    end if
    drawRectF ox,oy,s,s,word 8 of rule
  end if
end expandRule

Before (re)drawing the quadtrees, we need to clear the background.

on clearRect
  choose select tool
  drag from 0,0 to 512,256
  doMenu "Clear Picture"
end clearRect
on setMinSize m
  global gMinSize
  put min(128,max(1,m)) into m
  drawTextField 1,1,2,m
  put m into gMinSize
end setMinSize

To draw the quadtrees, we expand the rule "A" at position 0,0 and the rule "E" at position 256,0 .

on drawRules
  choose rect tool
  expandRule getRule("A"),0,0,256
  expandRule getRule("E"),256,0,256
  choose browse tool
end drawRules

To reset the rules, reset the contents of the rule field, then redraw the rule menu.

on resetRules
  repeat with i = 1 to 8
    put (numtochar(64+i) & " -> 0 0 0 0 or 0") into line i of background fld rules
  end repeat
end resetRules

initBackground is a helper function for setting up a new background. It creates a hidden field for the rules, then draws the menu.

on initBackground
  doMenu new field
  set the name of background field 1 to "rules"
  hide background field rules
  repeat with i = 1 to 8
    put (numtochar(64+i) & " -> 0 0 0 0 or 0") into line i of background fld rules
  end repeat
end initBackground

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