Again, reduce the level of useless work

chameleonic.p8

@@ -679,8 +679,13 @@ function rope:drag(
  for x,y in self:_rast(
   anc.x,anc.y,x,y
  ) do
-  self:_drag1(i(),x,y)
+  local a=self:_anc(i())
-  self:_tidy_up_gen()
+  if not (_point_eq(a, {x=x,y=y})) then
+   a.x=x
+   a.y=y
+   a.dirty=true
+   self:_tidy_up_gen()
+  end
  end
 end
 
@@ -748,17 +753,6 @@ function rope:_tidy_up_gen()
  end
 end
 
-function rope:_drag1(
- i,x,y
-)
- local a=self:_anc(i)
- if (_point_eq(a, {x=x,y=y})) return
- 
- a.x=x
- a.y=y
- a.dirty=true
-end
-
 function rope:_find_needed_anchors(i)
  if (i<=0) return false
  if (#self.ancs+1<i) return false
@@ -799,6 +793,9 @@ 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)
@@ -850,6 +847,11 @@ function rope:_elide_point(i)
 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
@@ -915,6 +917,21 @@ 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