Colour Objects (by random/by position)

I needed a script that would give a random colour to my leaves and also give a colour to them based on height so that I could use this to make the leaves at the back disappear first in autumn.

For the sake of functionality, I gave it three purposes:

Usage:

• select many objects
• adjust settings between height by colour / random colour / random greyscale
• run script

Update:

• I needed this to give an even distribution of colours, so introduced a new method which sorts based on position, then assigns a colour based on sort order. slightly long-winded code, sorry!

  
  
-- MixeScript snippet: Colour Objects (random/by pos)
-- Removes material from objects and applies a random colour, or colour based on their position.

--USAGE
-- select many objects
-- adjust settings between height by colour / random colour / random greyscale
-- run script

--SETTINGS
useposcolour = true --if false, uses a random colour.
greyscale = false -- if true then r=g=b (grey tones)
sortbasedcolouring = false -- if true, sorts objects then colours based on sort order. ensures even distribution of colours and no matching colours.
 
 
if sortbasedcolouring == false then
(
 minx = $.min.x
 maxx = $.max.x
 xdifference = maxx - minx
 miny = $.min.y
 maxy = $.max.y
 ydifference = maxy - miny
 minz = $.min.z
 maxz = $.max.z
 zdifference = maxz - minz
 sort 

 for o in $ do (
  o.mat = undefined
  
  xcolour = (o.center.x - minx) / xdifference * 255
  ycolour = (o.center.y - miny) / ydifference * 255
  zcolour = (o.center.z - minz) / zdifference * 255 
  
  if useposcolour then (
   r = zcolour ;  g = zcolour ;  b = zcolour
  ) else (
   if greyscale then (
    r = random 0 255 ;  g = r ;  b = r
   ) else (
    r = random 0 255 ;  g = random 0 255 ;  b = random 0 255
   )
  )
  
  o.wirecolor = [r,g,b]
 )
)
else 
(
 
 mysel = getcurrentselection()
  
 fn CompareX newobj prevobj =
 ( 
  case of
  (
   (newobj.center.x >  prevobj.center.x): 1
   (newobj.center.x <  prevobj.center.x): -1
   default:0
  )
 )
  
 fn CompareY newobj prevobj =
 ( 
  case of
  (
   (newobj.center.y >  prevobj.center.y): 1
   (newobj.center.y <  prevobj.center.y): -1
   default:0
  )
 )

 fn CompareZ newobj prevobj =
 ( 
  case of
  (
   (newobj.center.z >  prevobj.center.z): 1
   (newobj.center.z <  prevobj.center.z): -1
   default:0
  )
 )

 selsize = mysel.count
 --print ("SELSIZE = " + (selsize as string))

 qsort mysel CompareX
 for i = 1 to selsize do ( 
  newcolour = (((i-1.0) / (selsize-1.0) * 255) as string)
  mysel[i].wirecolor = [(newcolour as integer),mysel[i].wirecolor.g,mysel[i].wirecolor.b]
  --print ("XVALUE: i = " + (i as string) + " , colour = " + (mysel[i].wirecolor as string))
 )

 qsort mysel CompareY
 for i = 1 to selsize do (
  newcolour = (((i-1.0) / (selsize-1.0) * 255) as string)
  mysel[i].wirecolor = [mysel[i].wirecolor.r,(newcolour as integer),mysel[i].wirecolor.b]
  --print ("YVALUE: i = " + (i as string) + " , colour = " + (mysel[i].wirecolor as string))
 )

 qsort mysel CompareZ
 for i = 1 to selsize do (
  newcolour = (((i-1.0) / (selsize-1.0) * 255) as string)
  mysel[i].wirecolor = [mysel[i].wirecolor.r,mysel[i].wirecolor.g,(newcolour as integer)]
  --print ("ZVALUE: i = " + (i as string) + " , colour = " + (mysel[i].wirecolor as string))
 )

 --optionally, use this to greyscale.
 --for o in mysel do (o.wirecolor = [o.wirecolor.b,o.wirecolor.b,o.wirecolor.b])
)