diff --git a/chameleonic.p8 b/chameleonic.p8
index c03b108..d99a15d 100644
--- a/chameleonic.p8
+++ b/chameleonic.p8
@@ -214,6 +214,17 @@ function level:anchor_points()
  return pairs(self._anch)
 end
 
+function level:anchors_in(px0,py0,px1,py1)
+ ancs={}
+ for ax=px0\4,(px1+3)\4 do
+  for ay=py0\4,(py1+3)\4 do
+   local anc=self._anch[_amix(ax,ay)]
+   if (anc!=nil) add(ancs, anc)
+  end
+ end
+ return ancs
+end
+
 function level:point_anchor(px,py)
  local ax,ay=self:p2a(px,py)
  local anc=self._anch[_amix(ax,ay)]
@@ -575,7 +586,6 @@ function rope:_make_consistent()
   )
 
   if #self.latch.rec.todo==0 then
-   self:_tidy_up_gen()
    for i=0,#self.ancs do
     local a0=self:_anc(i)
     local a1=self:_anc(i+1)
@@ -665,49 +675,83 @@ function rope:drag(
  i,x,y
 )
  local anc=self:_anc(i())
+ local busy=self:busy()
+
  for x,y in self:_rast(
   anc.x,anc.y,x,y
  ) do
-  self:_drag1(i(),x,y)
-  self:_tidy_up_gen()
- end
-end
-
-function rope:_tidy_up_gen()
- if (self:busy()) return
-
- for i=0,#self.ancs+1 do
-  local a=self:_anc(i)
-  a.dirty=true
- end
-
- local a=0
- while a<=#self.ancs+1 do
-  local anc=self:_anc(a)
-  if anc.dirty and #anc.todo==0 then
-   while not self.under_destruction and (
-    self:_find_needed_anchors(a) or 
-    self:_find_touched_anchors(a) or
-    self:_elide_point(a) 
-   ) do end
-
-   anc.dirty=false
-   a=0
-  else
-   a+=1
+  local a=self:_anc(i())
+  if not (_point_eq(a,{x=x,y=y})) then
+   a.x=x
+   a.y=y
+   a.dirty=true
+   self.dirty=true
+   if (not busy) self:_tidy_up_gen()
   end
  end
 end
 
-function rope:_drag1(
- i,x,y
-)
- local a_old=self:_anc(i)
- local a_new={x=x,y=y}
- if (_point_eq(a_old, a_new)) return
- 
- a_old.x=x
- a_old.y=y
+function rope:_tidy_up_gen()
+ if (self.under_destruction) return
+ if (not self.dirty) return
+
+ local settled=true
+ local touched={}
+ local loop=function(f)
+  local a=0
+  while a<=#self.ancs+1 do
+   local anc=self:_anc(a)
+   if anc.dirty then
+    anc.seen=true
+    if self[f](self,a) then
+     settled=false anc.changed=true 
+    end
+   end
+   a+=1
+  end
+ end
+
+ local mark_unseen=function()
+  touched={}
+  for a=0,#self.ancs+1,1 do
+   local anc=self:_anc(a)
+   anc.seen=false
+   anc.changed=false
+  end
+ end
+
+ local propagate_dirty=function(f)
+  for a=0,#self.ancs+1,1 do
+   local a1=self:_anc(a)
+   if a1.dirty then
+    local a0=self:_anc(a-1)
+    if (a0!=nil) a0.dirty=true
+
+    local a2=self:_anc(a+1)
+    if (a2!=nil) a2.dirty=true
+   end
+  end
+ end
+
+ while true do
+  settled=true
+
+  mark_unseen()
+  propagate_dirty()
+
+  loop("_find_needed_anchors")
+  loop("_find_touched_anchors")
+  loop("_elide_point")
+
+  for a=0,#self.ancs+1,1 do
+   local anc=self:_anc(a)
+   if (anc.seen) anc.dirty=anc.changed
+  end
+
+  if (settled) break
+ end
+
+ self.dirty=false
 end
 
 function rope:_find_needed_anchors(i)
@@ -724,14 +768,8 @@ function rope:_find_needed_anchors(i)
  local anchors_bydist={}
  local x0,x2=_mnmx(a0.x,a2.x)
  local y0,y2=_mnmx(a0.y,a2.y)
- for _,a1 in level:anchor_points() do
-  -- the new anchor point must be in the bounding box
-  -- of the old line
-  -- note: this fudge never turned out necessary
-  -- i just would be ok with it
-  if x0-1<=a1.x and a1.x<=x2+1 and y0-1<=a1.y and a1.y<=y2+1 then
-   add(anchors_bydist,{el=a1,key=_linedist(a0,a1,a2)})
-  end
+ for a1 in all(level:anchors_in(x0-1,y0-1,x2+1,y2+1)) do
+  add(anchors_bydist,{el=a1,key=_linedist(a0,a1,a2)})
  end
  shellsort(anchors_bydist)
 
@@ -741,11 +779,9 @@ function rope:_find_needed_anchors(i)
    self:_can_stretch(a1,a2)
   then
    local id=self.id
-   add(self.ancs,{id=id,x=a1.x,y=a1.y,todo={}},i)
+   add(self.ancs,{id=id,x=a1.x,y=a1.y,dirty=true,todo={}},i)
    self.id+=1
 
-   self:_anc(i-1).dirty=true
-   self:_anc(i+1).dirty=true
    return true
   end
  end
@@ -758,19 +794,20 @@ function rope:_find_touched_anchors(i)
  local a0=self:_anc(i-1)
  local a2=self:_anc(i)
 
+ if (level:pcoll(a0.x,a0.y)) return false
+ if (level:pcoll(a2.x,a2.y)) return false
+
  for bx,by in self:_rast(a0.x,a0.y,a2.x,a2.y) do
   local a1=level:point_anchor(bx,by)
-  if a1!=nil and not _point_eq(a0,a1) and not _point_eq(a1,a2)
-   and _linedist(a0,a1,a2) < 0.01
+  if 
+   a1!=nil and not _point_eq(a0,a1) and not _point_eq(a1,a2)
+   and _linedist(a0,a1,a2) == 0.0
    -- and self:_can_stretch(p,a2)
   then
    local id=self.id
-   add(self.ancs,{id=id,x=a1.x,y=a1.y,todo={}},i)
+   add(self.ancs,{id=id,x=a1.x,y=a1.y,dirty=true,todo={}},i)
    self.id+=1
 
-   self:_anc(i-1).dirty=true
-   self:_anc(i+1).dirty=true
-
    return true
   end
  end
@@ -808,12 +845,15 @@ function rope:_elide_point(i)
  end
  
  deli(self.ancs,i)
- self:_anc(i-1).dirty=true
- self:_anc(i).dirty=true
  return true
 end
 
 function rope:_can_move_midpoint(a0,a1_0,a1_1,a2)
+ if (level:pcoll(a0.x,a0.y)) return false
+ if (level:pcoll(a2.x,a2.y)) return false
+ if (level:pcoll(a1_0.x,a1_0.y)) return false
+ if (level:pcoll(a1_1.x,a1_1.y)) return false
+
  if not self:_can_stretch(a1_0, a1_1) then
   return false
  end
@@ -823,7 +863,7 @@ function rope:_can_move_midpoint(a0,a1_0,a1_1,a2)
  if not self:_can_stretch(a1_1,a2) then
   return false
  end
- for x,y in self:_rastm(a1_0.x,a1_0.y,a1_1.x,a1_1.y) do
+ for x,y in self:_rastn(a1_0.x,a1_0.y,a1_1.x,a1_1.y,8,8) do
   local tm={x=x,y=y}
   if not self:_can_stretch(a0,tm) then
    return false
@@ -879,11 +919,26 @@ end
 function rope:_can_stretch(
  p1,p2
 )
+ -- faster implementation for straight lines
+ if p1.y\8==p2.y\8 then
+  local my=p2.y\8
+  for mx=p1.x\8,p2.x\8 do
+   if (level:mcoll(mx,my)) return false
+  end
+ end
+
+ if p1.x\8==p2.x\8 then
+  local mx=p2.x\8
+  for my=p1.y\8,p2.y\8 do
+   if (level:mcoll(mx,my)) return false
+  end
+ end
+
  if (level:pcoll(p1.x,p1.y)) return false
  if (level:pcoll(p2.x,p2.y)) return false
 
  local res=true
- for x,y in self:_rastm(p1.x,p1.y,p2.x,p2.y) do
+ for x,y in self:_rastn(p1.x,p1.y,p2.x,p2.y,8,8) do
   if level:pcoll(x,y) then
    res=false
    break
@@ -893,8 +948,8 @@ function rope:_can_stretch(
  return res
 end
 
-function rope:_rastm(
- x0,y0,x1,y1
+function rope:_rastn(
+ x0,y0,x1,y1,dx,dy
 )
  -- todo: more optimized implementation?
  local iter=self:_rast(x0,y0,x1,y1)
@@ -907,8 +962,8 @@ function rope:_rastm(
 
    if (x==nil) done=true return x1, y1
 
-   local x8 = x\8
-   local y8 = y\8
+   local x8 = x\dx
+   local y8 = y\dy
    if not (x8==prevx and y8==prevy) then 
     prevx,prevy=x8,y8
     return x,y
@@ -931,34 +986,27 @@ function rope:_rast(
  if (y0<y1) sy=1
 	
  local done=false,err
- local queue={}
  if dx>dy then
   err=dx/2.0
   return function()
-   if (queue==nil) return 
-   if (x==x1) queue=nil return x1,y1
-   if #queue==0 then
-    add(queue,{x,y})
-    err-=dy
-    if (err<0) y+=sy add(queue,{x,y}) err+=dx
-    x+=sx
-   end
-   return unpack(deli(queue,1))
+   if (done) return 
+   if (x==x1) done=true return x1,y1
+   local oldx,oldy=x,y
+   err-=dy
+   if (err<0) y+=sy err+=dx
+   x+=sx
+   return oldx,oldy
   end
  else
   err=dy/2.0
   return function()
-   if (queue==nil) return
-   if (y==y1) queue=nil return x1,y1
-   if #queue==0 then
-    add(queue,{x,y})
-   
-    local oldx,oldy=x,y
-    err-=dx
-    if (err<0) x+=sx add(queue,{x,y}) err+=dy
-    y+=sy
-   end
-   return unpack(deli(queue,1))
+   if (done) return
+   if (y==y1) done=true return x1,y1
+   local oldx,oldy=x,y
+   err-=dx
+   if (err<0) x+=sx err+=dy
+   y+=sy
+   return oldx,oldy
   end
  end
 end
@@ -1034,7 +1082,7 @@ function rope:_tug()
       if force or not level:pcoll(x,y) then
        s.x=x
        s.y=y
-       s.dirty=true
+       self.dirty=true
       end
       return true
      end}
@@ -1048,7 +1096,6 @@ function rope:_tug()
    end 
    for node=ancs[i-1].ix-1,ancs[i].ix+1 do
     local anc=self:_anc(node)
-    if (anc!=nil) anc.dirty=true
    end
    return
   end
@@ -1088,6 +1135,8 @@ function rope:_tug()
     mx0,my0,
     dmx,dmy
    ) 
+   -- be busy for 4 ticks while the crate moves
+   self:_anc(0).todo={{},{},{},{}}
   end
  end
 end