diff --git a/chameleonic.p8 b/chameleonic.p8
index f4a065b..9518c31 100644
--- a/chameleonic.p8
+++ b/chameleonic.p8
@@ -331,7 +331,7 @@ function level:draw()
 
  for _,pit in pairs(self._pits) do
   local px,py=pit.px,pit.py
-  local pr=self._pits[_mix(px+1,py)]
+  local pr=self._pits[_mix{px+1,py}]
 
   spr(pit.s,px,py)
   if pit.full then
@@ -362,7 +362,7 @@ function level:update()
   _apply(crate, crate.todo)
 
   if #crate.todo==0 then 
-   local pit=self._pits[_mix(crate.mx,crate.my)]
+   local pit=self._pits[_mix{crate.mx,crate.my}]
    if pit and not pit.full then
     add(remove,cix)
     crate.dead=true
@@ -388,7 +388,7 @@ function level:load_dynobjs()
  local crate_id=1
  for mx=0,15,1 do
   for my=0,15,1 do
-   local mxy=_mix(mx,my)
+   local mxy=_mix{mx,my}
    local px,py=mx*8,my*8
    local s=self:_mget(mx,my)
    local def=self:_get_cratedef(s)
@@ -413,7 +413,7 @@ function level:recollide_reanchor()
  self._coll={}
  for mx=0,15 do
   for my=0,15 do
-   local mxy=_mix(mx,my)
+   local mxy=_mix{mx,my}
    self._coll[mxy]=
     fget(self:_mget(mx,my),7) or
     self._crates[mxy]
@@ -434,7 +434,7 @@ function level:recollide_reanchor()
      not self:mcoll(mx1,my0) and
      not self:mcoll(mx1,my1)
     ) then
-     local key="GEOM"..mx0..","..my0..","..dx..","..dy
+     local key=_mix{"GEOM",mx0,my0,dx,dy}
      anch_new[key]= {
       max(mx0,mx1),max(my0,my1),adx=-dx,ady=-dy
      }
@@ -443,7 +443,7 @@ function level:recollide_reanchor()
   end
 
   for _,cr in pairs(self._crates) do
-   local key="CRATE"..cr.id..","..dx..","..dy
+   local key=_mix{"CRATE",cr.id,dx,dy}
    local mx0,my0=cr.mx,cr.my
    local mx1,my1=mx0+dx,my0+dy
    anch_new[key]={
@@ -462,11 +462,13 @@ function level:recollide_reanchor()
  end
  self._anch=anch_new
  self._anch_keys={}
- self._anch_by_position={}
+ self._anch_by={}
  for k,v in pairs(self._anch) do
+  local ax,ay=_anch_unpack(v)
   add(self._anch_keys,{key=k})
-  local pkey=_mix(_anch_unpack(v))
-  self._anch_by_position[pkey]=self._anch_by_position[pkey] or v
+  local pkey=_mix{ax,ay}
+  self._anch_by[pkey]=self._anch_by[pkey] or v
+  self._anch_by[_mix{ax,ay,v.adx,v.ady}]=v
  end
  shellsort(self._anch_keys)
  shellsort(moves)
@@ -481,7 +483,7 @@ function level:recollide_reanchor()
 end
 
 function level:win_at(mx,my)
- return self._wins[_mix(mx,my)]
+ return self._wins[_mix{mx,my}]
 end
 
 function level:anchor_points()
@@ -494,11 +496,17 @@ function level:anchor_points()
 end
 
 function level:anchor_at(point)
- return self._anch_by_position[_mix(_anch_unpack(point))]
+ return self._anch_by[_mix{_anch_unpack(point)}]
+end
+
+function level:anchor_at_tension(point,tension)
+ local ax,ay=_anch_unpack(point)
+ local adx,ady=_anch_unpack(tension)
+ return self._anch_by[_mix{ax,ay,adx,ady}]
 end
 
 function level:get_open_pit(mx,my)
- local pit=self._pits[_mix(mx,my)]
+ local pit=self._pits[_mix{mx,my}]
  if (pit and not pit.full) return pit
 end
 
@@ -520,7 +528,7 @@ function level:spawn_exit()
     -- next check: is at least one of
     -- nx or ny out of range [0, 15]?
     if (nx | ny) & 0xFFF0 ~= 0 then
-     self._wins[_mix(nx,ny)]=true
+     self._wins[_mix{nx,ny}]=true
     end
    end
   end
@@ -534,11 +542,11 @@ end
 
 function level:mcoll(mx,my)
  if ((mx | my) & 0xFFF0!=0) return true
- return self._coll[_mix(mx,my)]
+ return self._coll[_mix{mx,my}]
 end
 
 function level:get_crate(mx,my)
- return self._crates[_mix(mx,my)]
+ return self._crates[_mix{mx,my}]
 end
 
 function level:_mget(mx,my)
@@ -548,8 +556,10 @@ function level:_mget(mx,my)
  )
 end
 
-function _mix(mx,my)
-  return mx..","..my
+function _mix(arg)
+ local out=arg[1]
+ for i=2,#arg do out..=","..arg[i] end
+ return out
 end
 
 -- crate spec:
@@ -568,7 +578,7 @@ end
 
 function level:get_latch(dx,dy,px,py)
  local mx,my=px\8,py\8
- local mxy=_mix(mx,my)
+ local mxy=_mix{mx,my}
  
  local crate=self._crates[mxy]
  local dx1,dy1=-sgn0(dx),-sgn0(dy)
@@ -625,7 +635,7 @@ function level:can_move(
 end
 
 function level:tug_crate(mx0,my0,dmx,dmy)
- local mxy0=_mix(mx0,my0)
+ local mxy0=_mix{mx0,my0}
  local existing=self._crates[mxy0]
  if (not existing) return
  
@@ -640,7 +650,7 @@ function level:tug_crate(mx0,my0,dmx,dmy)
   {px=px1,py=py1}
  }
 
- self._crates[_mix(mx1,my1)]=existing
+ self._crates[_mix{mx1,my1}]=existing
 end
 
 -->8
@@ -1088,7 +1098,7 @@ function rope:draw(artificial_px,artificial_py)
 	 pset(x+p.adx,y,11)
 	 pset(x,y+p.ady,11)
 	end
- ]]
+ ]]--
 end
 
 function rope:drag_dst(xy)
@@ -1122,9 +1132,9 @@ function rope:relax()
   local n2=n1.next
   if (not n2) return
 
-  local anch=level:anchor_at(n1)
-  local wouldstick,position_new=would_stick(anch,n0,n1,n2)
-  if not (wouldstick or _anch_eq(n1,position_new)) then
+  local adxy,position_new=calc_tension(n0,n1,n2)
+  local anch=level:anchor_at_tension(n1,adxy)
+  if not anch or _anch_eq(n1,position_new) then
    self:_drag(n1,position_new,{_anch_unpack(n1)})
    _anch_del(n1)
   else n0=n0.next end
@@ -1200,9 +1210,9 @@ function rope:_check_pinch()
  return true
 end
 
-function would_stick(anchor,xy0,xy1,xy2)
+function calc_tension(xy0,xy1,xy2)
  local x0,y0=_anch_unpack(xy0)
- local x1,y1=_anch_unpack(xy1 or anchor)
+ local x1,y1=_anch_unpack(xy1)
  local x2,y2=_anch_unpack(xy2)
 
  local dx,dy=x2-x0,y2-y0
@@ -1226,10 +1236,12 @@ function would_stick(anchor,xy0,xy1,xy2)
   x1_new,y1_new=x0+(y1-y0)/dy*dx,y1
   ady,adx=signs(dx,x1_new-x1)
  end
+ return {adx,ady},{x1_new,y1_new}
+end
 
- return 
-  anchor and anchor.adx==adx and anchor.ady==ady,
-  {x1_new,y1_new}
+function would_stick(anch,tens)
+ adx,ady=unpack(tens)
+ return anch.adx==adx and anch.ady==ady
 end
 
 function rope:experience_anchor_moves(moves)
@@ -1293,7 +1305,7 @@ function rope:_be_pushed_by1(anch_old,anch_new)
 
    (_which_side(anch_old,n0,n1)!= 
     _which_side(anch_new,n0,n1) 
-   ) and would_stick(anch_new,n0,nil,n1)
+   ) and would_stick(anch_new,calc_tension(n0,anch_new,n1))
   then
    local nx05,ny05
    if ax_new==ax_old then
@@ -1331,7 +1343,7 @@ function rope:_drag(n1,new,removing)
      local side_orig=_which_side(anchor,pivot,point_orig)
      local side_final=_which_side(anchor,pivot,point_final)
 
-     if (side_orig!=side_final and would_stick(anchor,pivot,nil,point_final)) add(eligible,{anchor,side_final})
+     if (side_orig!=side_final and would_stick(anchor,calc_tension(pivot,anchor,point_final))) add(eligible,{anchor,side_final})
     end
    end