pico-8 cartridge // http://www.pico-8.com
version 32
__lua__
--https://ztiromoritz.github.io/pico-8-shooter/
--https://github.com/ztiromoritz/pico-8-shooter/tree/master/p8 
function fps()
  f = stat(7)
  print("fps: "..f, 0, 120, 1)
end

t=0
bullets={}

function init_stars()
  stars={}
  star_cols={1,2,5,6,7,12}
  warp_f=3
  for i=1,#star_cols do
    for j=1,10 do
      local s={
        x=rnd(128),
        y=rnd(128),
        z=i,
        c=star_cols[i]
      }
      add(stars,s)
    end
  end
end

function init_enemies()
  enemies={}
  for i=1,10 do
    add(enemies, {
      sp=4,
      m_x=i*16,
      m_y=60-i*8,
      x=-32,
      y=-32,
      r=12,
    })
  end
end

function draw_enemies()
  for e in all(enemies) do
    spr(e.sp,e.x,e.y)
  end
end

function update_enemies()
  for e in all(enemies) do
    e.x = e.r*sin(t/50) + e.m_x
    e.y = e.r*cos(t/50) + e.m_y
  end
end

function init_player()
  player={
    h=3,
    sp=1,
    x=64,
    y=64,
  }
end

function draw_health()
  inc=10
  for i=1,player.h do
    spr(2,(inc*i),1)
  end 
end

function draw_player()
  spr(player.sp,player.x,player.y)
end

function update_player()
  if(t%6<3) then
    player.sp=0
  else
    player.sp=1
  end
end

function fire()
  local b={
    sp=3,
    x=player.x,
    y=player.y,
    dx=0,
    dy=-3,
  }
  add(bullets,b)
end

function draw_bullets()
  for b in all(bullets) do 
    spr(b.sp,b.x,b.y)
  end
end

function draw_stars()
  for s in all(stars) do
    pset(s.x,s.y,s.c)
  end
end

function update_stars()
  for s in all(stars) do
    s.y+=s.z*warp_f/10
    if s.y>128 then
      s.y=0
      s.x=rnd(128)
    end
  end
end

function _init()
  player_xpos=64
  player_ypos=64
  init_stars()
  init_player()
  init_enemies()
end

function _update60()
  t=t+1
  if ( t > 1000) then t=0 end

  for b in all(bullets) do
    b.x+=b.dx
    b.y+=b.dy
    if b.x < 0 or b.x > 128 or
      b.y < 0 or b.y > 128 then
      del(bullets,b)
    end
  end

  if (btn(0) and player.x > 0) player.x -= 2
  if (btn(1) and player.x < 127) player.x += 2
  if (btn(2) and player.y > 0) player.y -= 2
  if (btn(3) and player.y < 127) player.y += 2
  if btnp(4) then fire() end

  update_stars()
  update_player()
  update_enemies()
end

function _draw()
  cls()
  fps()
  draw_health()
  draw_stars()
  draw_player()
  draw_bullets()
  draw_enemies()
end




__gfx__
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