Ombre

globals [ kind ]

to-report Ombre [ a b steps sample ]
  let t sample / (steps - 1)
  if is-number? a [ set a extract-rgb a ]
  if is-number? b [ set b extract-rgb b ]
  ;; right: square-root of sum of scaled squares
  report (map [ [ aa bb ] -> sqrt(  (aa * aa * t) + (bb * bb * (1 - t) ) ) ] a b)
end 

to-report Bad-Ombre [ a b steps sample ]
  let t sample / (steps - 1)
  let argb a
  let brgb b
  ;; wrong: linear scaled values
  report (map [ [ aa bb ] -> ( (aa * t) + (bb * (1 - t) ) ) ] argb brgb)
end 

to-report Ombre2 [ a b steps sample ]
  if-else kind = "bad"
  [ report bad-ombre a b steps sample ]
  [ report ombre a b steps sample ]
end 

to setup-bad
  set kind "bad"
  setup
end 

to setup-good
  set kind "good"
  setup
end 

to setup
  clear-patches
  clear-turtles
  let t 0
  let rgbRed [255   0   0 ] ;; pure Red
  let rgbGreen [  0 255   0 ] ;; pure Green
  let rgbBlue [  0   0 255 ] ;; pure Blue
  let rgbYellow [ 255 255  0 ] ;; cyber Yellow
  ask patches
  [ let colorRight Ombre2 rgbRed rgbYellow        world-width  (pycor - min-pycor)
    let colorLeft  Ombre2 rgbBlue rgbGreen        world-width  (pycor - min-pycor)
    ;; output of these is then blended to get the final color
    let colorBottom-to-Top Ombre2 colorRight colorLeft world-height (pxcor - min-pxcor)
    set pcolor colorBottom-to-Top
  ]
  reset-ticks
end 

to magnify
  if not any? turtles [ create-turtles 1 [ set shape "circle 3" set size 10 ] ]
  ask turtles
  [ if-else mouse-inside?
    [ setxy mouse-xcor mouse-ycor ]
    [ setxy 0 0]
    set color pcolor
    set label round-rgb color
  ]
end 

to-report round-rgb [ this ]
    report (map [x -> int x ] this)
end 

to-report color-under-mouse
  if mouse-inside? [ report round-rgb [ pcolor ] of patch mouse-xcor mouse-ycor ]
  report "n/a"
end 

to go
   magnify
end