diff --git a/chameleonic.p8 b/chameleonic.p8
index 3401e84..ae900a5 100644
--- a/chameleonic.p8
+++ b/chameleonic.p8
@@ -234,10 +234,10 @@ function level:reinit(n)
  self.ix=n
  self.todo={}
  self.bigx,self.bigy=n%8,n\8
+ self.dirty=false
 
  self:load_dynobjs()
- self:recollide()
- self:reanchor(true)
+ self:recollide_reanchor()
  self:spawn_exit()
 end
 
@@ -309,10 +309,12 @@ function level:update()
  end
  for cix in all(remove) do
   self._crates[cix]=nil
+  self.dirty=true
  end
- if #remove>0 then
-  self:recollide()
-  self:reanchor()
+
+ if self.dirty then
+  self:recollide_reanchor()
+  self.dirty=false
  end
 end
 
@@ -344,7 +346,7 @@ function level:load_dynobjs()
  end
 end
 
-function level:recollide()
+function level:recollide_reanchor()
  self._coll={}
  for mx=0,15 do
   for my=0,15 do
@@ -354,9 +356,7 @@ function level:recollide()
     self._crates[mxy]
   end
  end
-end
 
-function level:reanchor()
  local anch_new={}
  for dxy in all{{-1,-1},{1,-1},{-1,1},{1,1}} do
   local dx,dy=unpack(dxy)
@@ -575,8 +575,7 @@ function level:tug_crate(mx0,my0,dmx,dmy)
  local px1,py1=mx1*8,my1*8
  existing.todo={
   {px=px1+dmx,py=py1+dmy,mx=mx1,my=my1,update=function()
-   self:recollide()
-   self:reanchor()
+   self.dirty=true
    return true
   end},
   {px=px1,py=py1}
@@ -1007,16 +1006,11 @@ function rope:draw(artificial_px,artificial_py)
   local n2=n1.next
   if n0!=nil and n2!=nil then
    if anch then
-    local _,_,_,adx,ady=would_stick(anch,n0.ax,n0.ay,n1.ax,n1.ay,n2.ax,n2.ay)
-    assert(adx==-1 or adx==0 or adx==1)
-    assert(ady==-1 or ady==0 or ady==1)
-    --assert(not (adx==0 and ady==0))
+    local _,_,_=would_stick(anch,n0.ax,n0.ay,n1.ax,n1.ay,n2.ax,n2.ay)
 
     local c=3
     if (anch.dropped) c=4
     rectfill(x+2,y+2,x+4,y+4,c)
-    pset(x+adx*2,y,9)
-    pset(x,y+ady*2,9)
    else
    rectfill(x+2,y+2,x+4,y+4,2)
    end
@@ -1163,33 +1157,35 @@ function rope:_check_sane()
 end
 
 function would_stick(anchor,x0,y0,x1,y1,x2,y2)
- if (x1==nil or y1==nil) x1,y1=anchor.ax,anchor.ay
-
- local dx=x2-x0
- local dy=y2-y0
+ x1,y1=x1 or anchor.ax,y1 or anchor.ay
 
+ local dx,dy=x2-x0,y2-y0
  if (x1==x0 and y1==y0) return 
  if (x1==x2 and y1==y2) return 
 
- local adx,ady
- local x1_new,y1_new
- if abs(dx)>abs(dy) then
-  if (x0>x2) dx,x0,y0,x2,y2=-dx,x2,y2,x0,y0
-  local dprop=(x1-x0)/dx
-  x1_new,y1_new=x1,y0+dprop*(y2-y0)
-  ady=sgn0(y1_new-y1)
-  adx=sgn0(y0-y2)*ady
- else
-  if (y0>y2) dy,x0,y0,x2,y2=-dy,x2,y2,x0,y0
-  local dprop=(y1-y0)/dy
-  x1_new,y1_new=x0+dprop*(x2-x0),y1
-  adx=sgn0(x1_new-x1)
-  ady=sgn0(x0-x2)*adx
+ local function switch_ends() 
+  dx,dy,x0,y0,x2,y2=-dx,-dy,x2,y2,x0,y0
  end
 
- local wouldnt=anchor==nil or (anchor.adx!=adx or anchor.ady!=ady)
+ local function signs(douter,dinner)
+  local adb=sgn0(dinner)
+  return -sgn0(douter)*adb,adb
+ end
 
- return not wouldnt,x1_new,y1_new,adx,ady
+ local adx,ady,x1_new,y1_new
+ if abs(dx)>abs(dy) then
+  if (x0>x2) switch_ends()
+  x1_new,y1_new=x1,y0+(x1-x0)/dx*dy
+  adx,ady=signs(dy,y1_new-y1)
+ else
+  if (y0>y2) switch_ends()
+  x1_new,y1_new=x0+(y1-y0)/dy*dx,y1
+  ady,adx=signs(dx,x1_new-x1)
+ end
+
+ return 
+  anchor and anchor.adx==adx and anchor.ady==ady,
+  x1_new,y1_new
 end
 
 function rope:experience_anchor_moves(moves)