pico-8 cartridge // http://www.pico-8.com
version 41
__lua__

-- vacuum gambit automatic brake test
-- by kistaro windrider

function usplit(str)
 return unpack(split(str))
end
function csv(s)
 local ret = split(s, "\n")
 for i, v in ipairs(ret) do
  ret[i] = type(v) == "string" and split(v) or { v }
 end
 return ret
end

-- generate standard "overlay"
-- constructor for type tt.
-- if more is defined, generated
-- new calls more(ret) after
-- ret is definitely not nil
-- before calling setmetatable.
-- use to initialize mutables.
--
-- if there was a previous new,
-- it is invoked on the new
-- object *after* more, because
-- this works better with the
-- `more` impls i use.
function mknew(tt, more)
 local mt, oldnew = { __index = tt }, tt.new
 tt.new = function(ret)
  if (not ret) ret = {}
  if (more) more(ret)
  if (oldnew) oldnew(ret)
  setmetatable(ret, mt)
  return ret
 end
end

function _init()
 pal(1,129,1)
 the_ship = ship.new()
 slomo = 0
 sloc = 0
 reroll()
end

function reroll()
 the_ship:reroll()
end

function _update60()
 if (btnp(4)) reroll()
 slomo += btnp(2) and -1 or btnp(3) and 1 or 0
 slomo = (slomo < 0) and 0 or (slomo > 60) and 60 or slomo
 sloc += 1
 if sloc > slomo then
  the_ship:update()
  sloc=0
 end
end

function _draw()
 cls(1)
 the_ship:draw()
end

-->8
-- ship

ship = {
 maxspd=4,
 thrust=0.25,
 drag=0.0625,
 y=32,
}
mknew(ship)

function ship:reroll()
 self.x=rnd(128)
 self.dx=rnd(2*self.maxspd)-self.maxspd
end

function ship:draw()
 if self.x < -7 then
  spr(2, 0, self.y-7)
  spr(2, 0, self.y+8)
 elseif self.x > 127 then
  spr(2, 120, self.y-7, 1, 1, true)
  spr(2, 120, self.y+8, 1, 1, true)
 else
  spr(1,self.x,self.y)
 end
end

function ship:update()
 local t = btn(0) and -1 or btn(1) and 1 or 0
 t *= self.thrust
 t = constrain(self, t)
 local s,lim=self.dx+t,self.maxspd
 local sg = sgn(s)
 s -= sg*self.drag
 if (sgn(s) != sg) s=0
 if (abs(s)>lim) s=sg*lim

 self.x += s
 self.dx = s
 self:add_sparks(t)
end

function ship:add_sparks(t)
end

-->8
-- constraints

function constrain(s, want)
 return want
end

-->8
-- fx

-- todo: spark ring buffer

__gfx__
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00000000675555758008888000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000675000750800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000067777500080000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000005555000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000