pico-8 cartridge // http://www.pico-8.com
version 32
__lua__
-- library

black = 0
dark_blue = 1
dark_purple = 2
dark_green = 3
brown = 4
dark_gray = 5
light_gray = 6
white = 7
red = 8
orange = 9
yellow = 10
green = 11
blue = 12
indigo = 13
pink = 14
peach = 15

function print_ctr(s,y,c)
  print(s,64 - #s * 2,y,c)
end
-->8
-- game code

bg = blue

function _init()
  -- button-press initial delay
  poke(0x5f5c, 2)
  -- button-press repeat
  poke(0x5f5d, 2)
  init_world()
end

function init_world()
  player = {}
  player.x = 64
  player.y = 16
  player.spr = 1

  drops = {}
  ramps = {}
  add_ramp(50,20,15,10)
  add_ramp(60,50,15,-15)
  add_ramp(48,60,20,0)
  add_ramp(45,75,10,30)
end

function add_ramp(x,y,dx,dy)
  r = {}
  r.x = x
  r.y = y
  r.dx = dx
  r.dy = dy
  add(ramps, r)
end

function _update()
  update_player()
  update_drops()
end

function update_player()
  if btn(0) then
    player.x -= 1
  end
  if btn(1) then
    player.x += 1
  end
  if btn(2) then
    player.y -= 1
  end
  if btn(3) then
    player.y += 1
  end
  if (player.y < 0) player.y = 0
  if (player.y > 127) player.y = 127
  if (player.x < 0) player.x = 0
  if (player.x > 127) player.x = 127

  if btnp(🅾️) then
    drop = {}
    drop.x = player.x
    drop.y = player.y
    add(drops, drop)
  end
end

function update_drop(d)
  if d.y == 127 or pget(d.x,d.y+1) == bg then
    d.y += 1
    return
  end

  left = pget(d.x-1,d.y) == bg and pget(d.x-1,d.y+1) == bg
  right = pget(d.x+1,d.y) == bg and pget(d.x+1,d.y+1) == bg

  if left and right then
    d.y += 1
    if rnd() < 0.5 then
      d.x -= 1
    else
      d.x += 1
    end
  elseif left then
    d.y += 1
    d.x -= 1
  elseif right then
    d.y += 1
    d.x += 1
  end
end

function update_drops()
  draw_world()
  new_drops = {}
  for i=1,#drops do
    d = drops[i]
    update_drop(d)
    if d.y < 128 then
      add(new_drops, d)
    end
  end
  drops = new_drops
end

function _draw()
  draw_world()
  spr(player.spr,player.x-1,player.y-1)
  print("drops: "..#drops, 1, 6, white)
end

function draw_world()
  cls(bg)
  foreach(drops, draw_drop)
  foreach(ramps, draw_ramp)
end

function draw_ramp(r)
  line(r.x,r.y,r.x+r.dx,r.y+r.dy,brown)
end

function draw_drop(drop)
  pset(drop.x, drop.y, white)
end

__gfx__
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00700700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000