pico-8 cartridge // http://www.pico-8.com
version 29
__lua__
-- amico8 demo2
-- demoscene style

t=0
mode=0
mode_t=0
mode_dur=300

-- plasma palette
function make_pal()
 for i=1,15 do
  pal(i,({1,2,8,14,9,10,11,7,6,13,5,12,3,4,0})[i],1)
 end
end

-- mode 0: plasma
function draw_plasma()
 for y=0,127,2 do
  for x=0,127,2 do
   local v=sin(x/32+t/20)
          +sin(y/24-t/15)
          +sin((x+y)/40+t/25)
          +cos(x/16-t/30)
   v=flr((v+4)*2)%16
   rectfill(x,y,x+1,y+1,v)
  end
 end
 print("plasma",48,2,7)
end

-- mode 1: tunnel
function draw_tunnel()
 local cx=64+sin(t/60)*20
 local cy=64+cos(t/45)*20
 for y=0,127,2 do
  for x=0,127,2 do
   local dx=x-cx
   local dy=y-cy
   local d=max(1,sqrt(dx*dx+dy*dy))
   local a=atan2(dx,dy)
   local u=flr(128/d+t/5)%16
   local v=flr(a*16+t/10)%16
   local c=(u+v)%16
   rectfill(x,y,x+1,y+1,c)
  end
 end
 print("tunnel",48,2,7)
end

-- mode 2: rotozoom
function draw_rotozoom()
 local a=t/50
 local s=sin(t/80)*2+3
 local ca=cos(a)
 local sa=sin(a)
 for y=0,127,2 do
  for x=0,127,2 do
   local dx=x-64
   local dy=y-64
   local u=flr((dx*ca-dy*sa)/s)
   local v=flr((dx*sa+dy*ca)/s)
   local c=(u%8<4)==(v%8<4) and 12 or 1
   if (u+v)%16<8 then c=c==12 and 7 or 2 end
   rectfill(x,y,x+1,y+1,c)
  end
 end
 -- scrolltext
 local msg="amico8 - pico-8 for amiga!   greets to all amiga users!   "
 local off=flr(t/2)%((#msg)*4)
 for i=1,#msg do
  local cx=i*4-off
  if cx>-4 and cx<132 then
   local cy=110+sin((cx+t*2)/80)*8
   print(sub(msg,i,i),cx,cy,7)
  end
 end
 print("rotozoom",44,2,7)
end

-- mode 3: starfield 3d
sx={}
sy={}
sz={}
for i=1,80 do
 sx[i]=rnd(256)-128
 sy[i]=rnd(256)-128
 sz[i]=rnd(100)+1
end

function draw_stars3d()
 cls(0)
 for i=1,80 do
  sz[i]-=2
  if sz[i]<1 then
   sx[i]=rnd(256)-128
   sy[i]=rnd(256)-128
   sz[i]=100
  end
  local px=sx[i]*128/sz[i]+64
  local py=sy[i]*128/sz[i]+64
  local r=max(0,3-sz[i]/30)
  if px>0 and px<128 and py>0 and py<128 then
   if r>1 then
    circfill(px,py,r,7)
   else
    pset(px,py,6)
   end
  end
 end
 -- 3d text
 local msg="amico8"
 for i=1,#msg do
  local cx=30+i*10
  local cy=58+sin(t/20+i/3)*10
  print(sub(msg,i,i),cx,cy,({8,9,10,11,12,14})[i])
 end
 print("starfield",43,2,7)
end

-- mode 4: copper bars
function draw_copper()
 for y=0,127 do
  local c=0
  for b=1,5 do
   local by=64+sin(t/30+b*0.2)*40+cos(t/20+b*0.3)*20
   local d=abs(y-by)
   if d<8 then
    local cols={1,2,8,14,7,14,8,2}
    c=cols[flr(d)+1] or 0
   end
  end
  line(0,y,127,y,c)
 end
 -- big logo
 local lx=20
 local ly=30+sin(t/25)*10
 print("\142",lx,ly,7)
 print("amico8",lx+2,ly+12,7)
 print("pico-8 for amiga",26,ly+22,6)
 print("copper bars",40,2,7)
end

-- main
function _update()
 t+=1
 mode_t+=1
 if mode_t>mode_dur then
  mode=(mode+1)%5
  mode_t=0
 end
 -- press z to skip
 if btnp(4) then
  mode=(mode+1)%5
  mode_t=0
 end
end

function _draw()
 cls(0)
 make_pal()
 if mode==0 then
  draw_plasma()
 elseif mode==1 then
  draw_tunnel()
 elseif mode==2 then
  draw_rotozoom()
 elseif mode==3 then
  draw_stars3d()
 elseif mode==4 then
  draw_copper()
 end
 pal()
 rectfill(0,120,127,127,0)
 print("z=next  mode "..(mode+1).."/5",16,122,5)
end