fix paths

segment/path update logic was somewhat backwards.

the result is definitely good enough for the kind of movements I want!

vacuum_gambit.p8

@@ -653,17 +653,17 @@ end
 
 function destination:anchor(fx, fy)
  local af = self.anchor_frac
- if (af == -1) return 55,63
- return lerp(fx, primary_ship.x + 4, af), lerp(fy, primary_ship.y + 4, af)
+ if (af == -1) return 51,59
+ return lerp(fx, primary_ship.x, af), lerp(fy, primary_ship.y, af)
 end
 
 function destination:target_from(fx, fy)
  local rx, ry = self:anchor(fx, fy)
  local xf, yf = self.x_off_frac, self.y_off_frac
  if (xf < 0) rx = lerp(rx, 0, -xf)
- if (xf > 0) rx = lerp(rx, 112, xf)
+ if (xf > 0) rx = lerp(rx, 104, xf)
  if (yf < 0) ry = lerp(ry, 0, -yf)
- if (yf > 0) ry = lerp(ry, 128, yf)
+ if (yf > 0) ry = lerp(ry, 120, yf)
  return rx, ry, self.accel_frac
 end
 
@@ -686,21 +686,21 @@ segment = mknew{
  -- dest_x, dest_y: stored
  --  current destination to
  --  figure out approach/depart
- -- [1..n]: destinations
+ -- dests[1..n]: destinations
  init = function(x)
   x.init = segment.reset
   mknew(x)
   if not x.mirror then
-   local mirrored = {mirror=x, init=segment.reset}
-   for i, v in ipairs(x) do
-    mirrored[i] = destination.new{
+   local mdests = {}
+   for i, v in ipairs(x.dests) do
+    mdests[i] = destination.new{
      anchor_frac=v.anchor_frac,
      accel_frac=v.accel_frac,
      x_off_frac=-v.x_off_frac,
      y_off_frac=v.y_off_frac,
     }
    end
-   x.mirror = mknew(x.new(mirrored))
+   x.mirror = mknew(x.new{mirror=x, init=segment.reset, dests=mdests})
   end
  end
 }
@@ -714,7 +714,7 @@ function segment:reset()
 end
 
 function segment:target_from(fx, fy)
- local rx, ry, af = self[self.current_idx]:target_from(fx, fy)
+ local rx, ry, af = self.dests[self.current_idx]:target_from(fx, fy)
  self.dest_x, self.dest_y = rx, ry
  return rx, ry, af
 end
@@ -725,7 +725,8 @@ function segment:update(x, y)
  if (rem > 0) rem -= 1
 
  if self:should_step(x, y) then
-  if self.current_idx == #self then
+  self.prev_x, self.prev_y, self.was_approaching = false, false, false
+  if self.current_idx == #self.dests then
    self.current_idx = self.loop_idx
    if (rem < 0) rem += 1
   else
@@ -737,45 +738,40 @@ function segment:update(x, y)
 end
 
 function segment:should_step(x, y)
- local dest_x, dest_y, ret = self.dest_x, self.dest_y, false
+ local dest_x, dest_y = self.dest_x, self.dest_y
  local dx1, dy1 = x - dest_x, y-dest_y
- if abs(dx1) <= 4 and abs(dy1) <= 4 then
-  self.was_approaching = false
-  ret = true
- end
+ if (abs(dx1) <= 1.5 and abs(dy1) <= 1.5) return true
  if self.prev_x then
   local dx0, dy0 = self.prev_x - dest_x, self.prev_y - dest_y
-  if dx1 * dx1 + dy1 * dy1 > dx0 * dx0 + dy0 * dy0 then
-   if self.was_approaching then
-    self.was_approaching = false
-    ret = true
-   end
+  local d12, d02 = dx1 * dx1 + dy1 * dy1, dx0 * dx0 + dy0 * dy0
+  if d12 > d02 then
+   if (self.was_approaching) return true
   else
+   if (d12 == d02 and self.was_approaching) return true
    self.was_approaching = true
   end
  end
  self.prev_x, self.prev_y = x, y
- return ret
+ return false
 end
 
 path = mknew {
  loop_idx = 1,
- -- [1..n]: destinations
+ -- segs[1..n]: segments or subpaths
  init=function(x)
   if not x.mirror then
-   local mirrored = {
-    mirror = x,
-    loop_idx = x.loop_idx,
-   }
-   for i, v in ipairs(x) do
-    mirrored[i]=v.mirror
+   local msegs = {}
+   for i, v in ipairs(x.segs) do
+    msegs[i]=v.mirror
    end
-   x.mirror = path.new(mirrored)
+   x.mirror = path.new{mirror=x, loop_idx=x.loop_idx, segs=msegs}
   end
   x.init = function(y)
-   for i, v in ipairs(x) do
-    y[i]=v.new{}
+   local ysegs = {}
+   for i, v in ipairs(x.segs) do
+    ysegs[i]=v.new{}
    end
+   y.segs = ysegs
    y:reset()
   end
   mknew(x)
@@ -784,22 +780,27 @@ path = mknew {
 
 function path:reset()
  self.current_idx = 1
+ for s in all(self.segs) do
+  s:reset()
+ end
 end
 
 function path:target_from(fx, fy)
- return self[self.current_idx]:target_from(fx, fy)
+ return self.segs[self.current_idx]:target_from(fx, fy)
 end
 
 function path:update(x, y)
- local idx = self.current_idx
- if self[idx]:update(x, y) then
-  if idx == #self then
+ local idx, segs = self.current_idx, self.segs
+ if not segs[idx]:update(x, y) then
+  segs[idx]:reset()
+  if idx == #segs then
    self.current_idx = self.loop_idx
-   return true
+   return
   else
    self.current_idx = idx+1
   end
  end
+ return true
 end
 
 -->8
@@ -1498,14 +1499,33 @@ ship_f = mknew(ship_m.new{
 })
 
 diamond_loop = segment.new{
- destination.new{
-  x_off_frac=0.25
- }, destination.new{
-  y_off_frac=0.25
- }, destination.new {
-  x_off_frac = -0.25
- }, destination.new {
-  y_off_frac = -0.25
+ dests = {
+  destination.new{
+   x_off_frac=0.25
+  }, destination.new{
+   y_off_frac=0.25
+  }, destination.new {
+   x_off_frac = -0.25
+  }, destination.new {
+   y_off_frac = -0.25
+  },
+ },
+}
+
+park = segment.new{
+ dests = {
+  destination.new{
+   accel_frac = 0
+  }
+ }
+}
+
+diamond_bounce = path.new{
+ segs = {
+  park,
+  diamond_loop,
+  park,
+  diamond_loop.mirror,
  },
 }
 
@@ -1530,17 +1550,15 @@ ship_skirmisher = mknew(ship_f.new{
  fire_off_y = 7,
  xmin = -8,
  xmax = 112,
- path = diamond_loop,
+ path = diamond_bounce,
 })
 
 function ship_skirmisher:reset_bounds()
- self.xmin, self.xmax, self.ymin, self.ymax = -8, 112, 0, 120
+ self.xmin, self.xmax, self.ymin, self.ymax = -8, 112, 0, 128
 end
 
 function ship_skirmisher:act()
- local tx, ty, af = self.path:target_from(self.want_x+4, self.want_y+4)
- tx -= 4
- ty -= 4
+ local tx, ty, af = self.path:target_from(self.want_x, self.want_y)
  if af <= 0 then
   self.xmin, self.xmax, self.ymin, self.ymax = tx,tx,ty,ty
   return 0,0
@@ -1553,7 +1571,7 @@ end
 
 function ship_skirmisher:move()
  if (not ship_f.move(self)) return
- if (not self.path:update(self.x+4, self.y+4)) self.path:reset()
+ if (not self.path:update(self.x, self.y)) self.path:reset()
  return true
 end