grape/src/main.moon

width, height = love.graphics.getDimensions!
rng = love.math.newRandomGenerator 0
types = 7
radius = 4
colors = {}
interactions = {}
universe = {}

physics = (a, b) ->
  dx = a.x - b.x
  dy = a.y - b.y
  ds = dx * dx + dy * dy
  theta = math.atan2 dy, dx
  x = math.cos theta
  y = math.sin theta

  f = interactions["#{a.n}.#{b.n}"](ds)
  a.vx += f * x
  a.vy += f * y

  f = interactions["#{b.n}.#{a.n}"](ds)
  b.vx += f * x
  b.vy += f * y

for a = 1, types
  for b = 1, types
    A = rng\randomNormal 0.5, 0
    aa = rng\randomNormal 5, 10
    B = rng\randomNormal 0.5, 0
    bb = rng\randomNormal 5, 10
    interactions["#{a}.#{b}"] = (ds) ->
      if ds < radius^0.5
        return 1 / ds
      else
        return A * (ds^0.5 - aa)
    interactions["#{b}.#{a}"] = (ds) ->
      if ds < radius^0.5
        return 1 / ds
      else
        return B * (ds^0.5 - bb)

-- for k,v in pairs interactions
--   print k,v

for a = 1, types
  colors[a] = { rng\random!, rng\random!, rng\random!, 1 }

class Particle
  new: (@n=1, x, y) =>
    @x = x or love.math.random 0, width
    @y = y or love.math.random 0, height
    @vx = 0
    @vy = 0

for i=1, 2
  table.insert universe, Particle(love.math.random 1, types)

love.update = (dt) ->
  for a = 1, #universe - 1
    for b = a + 1, #universe
      physics(universe[a], universe[b])

  for particle in *universe
    particle.vx *= 0.01
    particle.vy *= 0.01
    particle.x += particle.vx * dt
    particle.y += particle.vy * dt

love.draw = ->
  for particle in *universe
    love.graphics.setColor colors[particle.n]
    love.graphics.circle "fill", particle.x, particle.y, radius

love.keypressed = (key) ->
  love.event.quit! if key == "escape"