Elide points as needed

chameleonic.p8

@@ -1047,9 +1047,9 @@ function rope:draw(artificial_dx,artificial_dy)
   local color=8
   if (highlight==0) color=12
   if self.latch.dx==-1 and self.latch.dy==0 then
-   rectfill(x+1,y,x+3,y+1,color)
+   rectfill(x+1,y-1,x+3,y,color)
   elseif self.latch.dx==1 and self.latch.dy==0 then
-   rectfill(x-1,y,x-3,y+1,color)
+   rectfill(x-1,y-1,x-3,y,color)
   elseif self.latch.dx==0 and self.latch.dy==-1 then
    rectfill(x,y+1,x-1,y+3,color)
   elseif self.latch.dx==0 and self.latch.dy==1 then
@@ -1090,17 +1090,69 @@ function rope:drag_src(x,y)
  self:drag(self.src,x,y)
 end
 
-function rope:drag(
+function rope:drag(n1,ax_new,ay_new)
- n1,ax_new,ay_new
-)
  -- TODO: stepwise?
- rope:_drag1(n1,ax_new,ay_new)
+ self:_relax()
+ self:_drag(n1,ax_new,ay_new)
+ self:_relax()
+end
+
+function rope:_relax()
+ local n0=self.src
+ while true do
+  if (n0==nil) return
+  local n1=n0.next
+  if (n1==nil) return
+  local n2=n1.next
+  if (n2==nil) return
+
+  if n1.associated_with!=nil then
+   local x0,y0=n0.ax,n0.ay
+   local x1,y1=n1.ax,n1.ay
+   local x2,y2=n2.ax,n2.ay
+
+   if (x0>x2) x0,y0,x2,y2=x2,y2,x0,y0
+
+   local dx=x2-x0
+   local dy=y2-y0
+
+   local adx,ady
+   local x1_new,y1_new
+   if abs(dx)>abs(dy) then
+    local dprop=(x1-x0)/dx
+    x1_new,y1_new=x1,y0+dprop*(y2-y0)
+    ady=sgn0(y1_new-y1)
+    adx=0
+    if (y0>y2) adx=ady
+    if (y0<y2) adx=-ady
+   else
+    local dprop=(y1-y0)/dy
+    x1_new,y1_new=x0+dprop*(x2-x0),y1
+    adx=sgn0(x1_new-x1)
+    ady=0
+    if (y0>y2) ady=adx
+    if (y0<y2) ady=-adx
+   end
+
+   if adx!=0 and ady!=0 and (n1.associated_with.adx!=adx or n1.associated_with.ady!=ady) then
+    --self:_drag(n1,x1_new,y1_new)
+    n0=n1.prev
+    n2=n1.next
+    n0.next=n2
+    n2.prev=n0
+    n1.next=nil
+    n1.prev=nil
+   else n0=n0.next end
+  else n0=n0.next end
+ end
 end
 
 -- TODO: Upon adding a point, start from there to see if we need another
 -- rather than adding at most one
-function rope:_drag1(n1,ax1_new,ay1_new)
+function rope:_drag(n1,ax1_new,ay1_new)
  local function _sweep_radar(ax_pivot,ay_pivot,ax_far0,ay_far0,ax_far1,ay_far1)
+  if (ax_far0==ax_far1 and ay_far0==ay_far1) return nil
+
   if ax_far0==ax_far1 then
    local ax_far=ax_far0
    local ax0,ax1=_mnmx(ax_pivot,ax_far)
@@ -1126,6 +1178,8 @@ function rope:_drag1(n1,ax1_new,ay1_new)
    for ax_far_new in _stepfrom(ax_far0,ax_far1) do
     for _,anchor in level:anchor_points() do
      if 
+      -- anchor.ax!=ax_pivot and anchor.ay!=ay_pivot and
+      -- anchor.ax!=ax_new and anchor.ay!=ay_new and
       (ay0<=anchor.ay and anchor.ay<=ay1) and 
       _which_side(anchor.ax,anchor.ay,ax_pivot,ay_pivot,ax_far_old,ay_far)!=
       _which_side(anchor.ax,anchor.ay,ax_pivot,ay_pivot,ax_far_new,ay_far)
@@ -1141,13 +1195,17 @@ function rope:_drag1(n1,ax1_new,ay1_new)
  end
 
  local ax1_old,ay1_old=n1.ax,n1.ay
+ n1.ax=ax1_new
+ n1.ay=ay1_new
 
  local n0=n1.prev
  while true do
   if (n0==nil) break
   local anch=_sweep_radar(n0.ax,n0.ay,ax1_old,ay1_old,ax1_new,ay1_new)
   if (anch==nil) break
-  local n05={ax=anch.ax,ay=anch.ay,prev=n0,next=n1}
+  if (anch.ax==n0.ax and anch.y==n0.ay) break
+  if (anch.ax==n1.ax and anch.y==n1.ay) break
+  local n05={ax=anch.ax,ay=anch.ay,associated_with=anch,prev=n0,next=n1}
   n0.next=n05
   n1.prev=n05
   n0=n05
@@ -1158,14 +1216,13 @@ function rope:_drag1(n1,ax1_new,ay1_new)
   if (n2==nil) break
   local anch=_sweep_radar(n2.ax,n2.ay,ax1_old,ay1_old,ax1_new,ay1_new)
   if (anch==nil) break
-  local n15={ax=anch.ax,ay=anch.ay,prev=n1,next=n2}
+  if (anch.ax==n1.ax and anch.y==n1.ay) break
+  if (anch.ax==n2.ax and anch.y==n2.ay) break
+  local n15={ax=anch.ax,ay=anch.ay,associated_with=anch,prev=n1,next=n2}
   n1.next=n15
   n2.prev=n15
   n2=n15
  end
-
- n1.ax=ax1_new
- n1.ay=ay1_new
 end
 
 function _stepfrom(x0,x1)