sprite renderer and parallax drifting thing renderer

vacation.p8

@@ -1485,9 +1485,72 @@ function spark:draw()
  spr(48+self.f\2, self.x, self.y)
 end
 
+-- other fields: level, item
+-- level must provide:
+--  function :pdone(item)
+--  field .pdx (scrolling parallax dx)
+-- item must provide:
+--  drawable api
+--  .x readwrite (draw coord)
+--  .w (width)
+parallax = {
+ dx=0,
+ z=1,
+}
+mknew(parallax)
+
+function parallax:u()
+ local item = self.item
+ if item:u() then
+  self.level:pdone(self)
+  return true
+ end
+
+ item.x += self.dx
+ item.x += self.level.pdx * self.z
+
+ if item.x > 256 or item.x + item.w < -128 then
+  self.level:pdone(self)
+  return true
+ end
+end
+
+function parallax:draw()
+ self.item:draw()
+end
+
+spritem = {
+ s = {0},
+ sw = 1,
+ sh = 1,
+ i = 1,
+ xf = -1,
+ f = 4,
+ x = 0,
+ y = 0,
+}
+mknew(spritem, function(self)
+ self.w = (self.sw or spritem.sw) << 3
+ self.h = (self.sh or spritem.sh) << 3
+end)
+
+function spritem:u()
+ self.xf += 1
+ if self.xf > self.f then
+  self.i += 1
+  if (self.i > #self.s) self.i = 1
+  self.xf = 0
+ end
+end
+
+function spritem:draw()
+ spr(self.s[self.i], self.x, self.y, self.sw, self.sh, self.flipx, self.flipy)
+end
+ 
 arcade_level = {
  score=0,
  wordwait = 90,
+ pdx=0,
 }
 mknew(arcade_level, function(x)
  x.phin = toyphin.new{