christmas_tree.coffee

lines = 35
columns = 44
distance = (x1, y1, x2, y2) ->
  Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2))

circleX = -1.5
circleY = -0.5
# radius = distance from treetop
circleRadius = distance(circleX, circleY, 0.5, 0) - 0.001

# trunk starts where circle intercepts y axis
trunkY = circleY + Math.sqrt(circleRadius * circleRadius - circleX * circleX)

baseStyling = 'background-color: #000;'
decorationStyling = 'color: #FFFFCC;'
branchStyling = 'color: #060;'
starStyling = 'color: #443'
trunkStyling = 'color: #822;'
characters = []
css = []

addBranchCharacter = ->
  if Math.random() < 0.1 || y == 0
    characters.push '%c*'
    css.push baseStyling + decorationStyling
  else
    characters.push '%c*'
    css.push baseStyling + branchStyling

addStemCharacter = ->
  characters.push '%cO'
  css.push baseStyling + trunkStyling

addSpaceCharacter = ->
  if Math.random() < 0.04
    characters.push '%c.'
    css.push baseStyling + starStyling
  else
    characters.push '%c '
    css.push baseStyling

for line in [-3..lines]
  y = line / lines
  for col in [-3..columns+3]
    x = col / columns
    if y < trunkY
      if distance(x, y, circleX, circleY) > circleRadius and distance(x, y, 1 - circleX, circleY) > circleRadius
        addBranchCharacter()
      else
        addSpaceCharacter()
    else
      if Math.abs(x - 0.5) < 0.05
        addStemCharacter()
      else
        addSpaceCharacter()
  characters.push '\n'

console.log.apply(console,[characters.join('')].concat(css))