breath signal layer

might want to make it more subtle later but I'm zonking myself with it
for now. can just add a fuzz stage to it if I want. these colors are not
final, but I think I do not want to do anything clever with bitplane
interference at this time -- this effect is good as-is.

vacation.p8

@@ -482,6 +482,76 @@ function fuzzy_stripey:draw()
  end
 end
 
+
+--@musurca & @felice
+function cminskycirc(r,c)
+ local j,k,rat=r,0,1/r
+ poke(0x5f25,c) --set color
+ for i=1,r*0.785 do
+  k-=rat*j
+  j+=rat*k
+  pset(63.5+j,63.5+k)
+  pset(63.5+j,63.5-k)
+  pset(63.5-j,63.5+k)
+  pset(63.5-j,63.5-k)
+  pset(63.5+k,63.5+j)
+  pset(63.5+k,63.5-j)
+  pset(63.5-k,63.5+j)
+  pset(63.5-k,63.5-j)
+ end
+ pset(63.5,63.5-r)
+ pset(63.5,63.5+r)
+ pset(63.5-r,63.5)
+ pset(63.5+r,63.5)
+end
+
+breather = {
+ colors = {1,2,4,2,1},
+ sep = 5,
+ speed=240,
+ f=0,
+}
+mknew(breather)
+
+function breather:update()
+ local f = self.f + 1
+ if (not self.on) f = 0
+ if (f >= self.speed) f = -self.speed
+ if f == 0 and self.nextspeed then
+  self.speed = self.nextspeed
+  self.nextspeed = nil
+ end
+ self.f = f
+end
+
+function easeinout(t)
+ if(t<.5) then
+     return t*t*t*4
+ else
+     t-=1
+     return 1-t*t*t*-4
+ end
+end
+
+function breather:draw()
+ fillp(0)
+ local cols, f, spd, sep = self.colors, self.f, self.speed, self.sep
+ local stall = sep * (#cols - 1)
+ local cap = spd-stall
+ if (f >= 0) f += stall
+ for i,c in ipairs(cols) do
+  local ef = f - (i-1)*sep
+  ef = abs(ef) - stall
+  if ef <= cap and ef > 0 then
+   cminskycirc(easeinout(ef/cap)<<6,c)
+  end
+ end
+end
+
+function breather:starting_reverse()
+ return self.f + self.speed < self.sep * #self.colors
+end
+
 -->8
 -- awakener
 
@@ -1027,7 +1097,11 @@ function start_game()
    f = function()
     pal()
     clear_alt_pal_bits()
-    return view.of{bg.new(), fuzzy_stripey.new{interval=7, tries=5}}
+    return view.of{
+     bg.new(),
+     fuzzy_stripey.new{interval=7, tries=5},
+     breather.new{on=true},
+    }
    end,
   },
  }