-- Replace side direction drawings only. Keep front/back contact repairs.
local src=app.open('art/sprites/fiddler_walk_contacts_v1.png')
local atlas=Image(src.cels[1].image);src:close()
for row,name in ipairs({'west','east'}) do
 local path=app.params[name]
 local source=app.open(path)
 local keys=Image(source.cels[1].image);source:close()
 for col=0,3 do
  local frame=Image(48,64,ColorMode.RGB)
  frame:drawImage(keys,Point(-col*48,0))
  -- Depth shading identifies the near/far legs when their contact silhouettes
  -- overlap. The opposite half-cycle swaps which leg crosses in front.
  if name=='east' and col>=2 then
   for y=46,61 do for x=12,39 do
    local c=frame:getPixel(x,y)
    local r,g,b,a=app.pixelColor.rgbaR(c),app.pixelColor.rgbaG(c),app.pixelColor.rgbaB(c),app.pixelColor.rgbaA(c)
    if a>0 and r>g and g>=b then
     local far=(col==2 and x>=24) or (col==3 and x<=26)
     local mult=far and 0.73 or 1.22
     frame:drawPixel(x,y,app.pixelColor.rgba(math.min(255,math.floor(r*mult)),math.min(255,math.floor(g*mult)),math.min(255,math.floor(b*mult)),a))
    end
   end end
  end
  for phase=0,1 do
   local index=col*2+phase
   local shifted=Image(48,64,ColorMode.RGB)
   local bob=(col%2==1 and phase==0) and -1 or 0
   shifted:drawImage(frame,Point(0,bob))
   if bob~=0 then
    local bottom=-1
    for pixel in frame:pixels() do if app.pixelColor.rgbaA(pixel())>0 then bottom=math.max(bottom,pixel.y) end end
    for x=0,47 do shifted:drawPixel(x,bottom,frame:getPixel(x,bottom)) end
   end
   for y=0,63 do for x=0,47 do atlas:drawPixel(index*48+x,row*64+y,shifted:getPixel(x,y)) end end
  end
 end
end
local out=Sprite(384,256,ColorMode.RGB);out.cels[1].image=atlas
out:saveAs(app.params.output);out:close()