-- ImageGen supplies the pose. Preserve limb lengths; only the heels rise.
local src=app.open(app.params.source)
local img=Image(src.cels[1].image)
local cells=dofile(app.params.boxes)
for p in img:pixels() do
  local c=p()
  if app.pixelColor.rgbaA(c)>=192 then p(app.pixelColor.rgba(app.pixelColor.rgbaR(c),app.pixelColor.rgbaG(c),app.pixelColor.rgbaB(c),255)) else p(0) end
end
local maxw,maxh=0,0
for _,b in ipairs(cells) do maxw,maxh=math.max(maxw,b.w),math.max(maxh,b.h) end
local factor=math.min(40/maxw,44/maxh)
local atlas=Image(144,64,ColorMode.RGB)
local frames={}
local neutral,raised
for i,b in ipairs(cells) do
  local crop=Image(b.w,b.h,ColorMode.RGB);crop:drawImage(img,Point(-b.x,-b.y))
  local tmp=Sprite(b.w,b.h,ColorMode.RGB);tmp.cels[1].image=crop
  local w,h=math.floor(b.w*factor+0.5),math.floor(b.h*factor+0.5)
  app.command.SpriteSize{ui=false,width=w,height=h,method='nearest-neighbor'}
  local base=Image(48,64,ColorMode.RGB)
  base:drawImage(tmp.cels[1].image,Point(math.floor((48-w)/2),61-h));tmp:close()
  if i==1 then
    neutral=Image(base)
  elseif i==2 then
    -- Source pose 3 also drew longer trousers. Keep the complete neutral
    -- head, torso and legs; borrow only the bent sleeves/forearms from pose 2.
    local arms=base
    base=Image(neutral)
    for y=35,51 do
      for x=0,18 do base:putPixel(x,y,arms:getPixel(x,y)) end
      for x=30,47 do base:putPixel(x,y,arms:getPixel(x,y)) end
    end
    raised=Image(base)
  else
    base=Image(raised)
  end
  local out=Image(48,64,ColorMode.RGB)
  local lift=i-1
  -- Move the complete figure by 0/1/2 pixels. Every shin/thigh/torso row
  -- retains its original size. The short toe contacts stay on the floor;
  -- only the underside of the boots changes as his heels lift.
  out:drawImage(base,Point(0,-lift))
  for y=61-lift,60 do
    for x=0,47 do out:putPixel(x,y,base:getPixel(x,60)) end
  end
  frames[i]=out;atlas:drawImage(out,Point((i-1)*48,0))
end
src:close()
local sheet=Sprite(144,64,ColorMode.RGB);sheet.cels[1].image=atlas;sheet:saveAs(app.params.output);sheet:close()
if app.params.preview_sheet then
  local strip=Sprite(144,64,ColorMode.RGB);strip.cels[1].image=atlas
  app.command.SpriteSize{ui=false,width=432,height=192,method='nearest-neighbor'}
  strip:saveAs(app.params.preview_sheet);strip:close()
end
local gif=Sprite(48,64,ColorMode.RGB)
local sequence={1,2,3,2,1}
local durations={0.65,0.12,1.0,0.12,0.3}
for i,index in ipairs(sequence) do
  if i>1 then gif:newFrame() end
  gif.cels[i].image=frames[index];gif.frames[i].duration=durations[i]
end
app.command.SpriteSize{ui=false,width=144,height=192,method='nearest-neighbor'}
gif:saveAs(app.params.preview);gif:close()
print('Tiptoe heel lift0/1/2px; full figure translated without stretching limbs.')