staggered "xp", "hp" labels in UI

"x" looks pretty bad with a drop shadow! will tweak soon anyway

autobrake_test.p8

@@ -81,9 +81,10 @@ function _draw()
  print("dx: ".. the_ship.dx, 20, 86, 7)
  meter(80, 86, 128, 90, the_ship.dx/the_ship.maxspd/2)
  print("x: "..the_ship.x, 24, 92, 7)
+ print("bx: "..gbx, 20, 98, 7)
 
- print("xmin:"..tostr(constraints.xmin), 12, 102, 7)
+ print("xmin:"..tostr(constraints.xmin), 12, 108, 7)
- print("xmax:"..tostr(constraints.xmax), 12, 108, 7)
+ print("xmax:"..tostr(constraints.xmax), 12, 114, 7)
 end
 
 function meter(x0, y0, x1, y1, frac)
@@ -127,26 +128,24 @@ function ship:draw()
   spr(1,self.x,self.y)
  end
 
- if (self.dx == 0) return
+ --if (self.dx == 0) return
  local bd, f = brake_dist(self.dx, self.thrust + self.drag)
- local bdx = self.x+bd-2
+ gbx = self.x+bd
- spr(3, bdx,self.y-2)
+ spr(3, gbx-2,self.y-2)
- print(tostr(f), bdx, self.y - 8, 14)
+ print(tostr(f), gbx-2, self.y - 8, 14)
 end
 
 function calc_velocity(v0, t, vmax, drag)
- local v1 = v0 + t
+ v0 = mid(v0 + t, vmax, -vmax)
- local sg = sgn(v1)
+ return v0 - mid(drag, -drag, v0)
- v1 -= sg*drag
- if (sgn(v1) != sg) return 0
- if (abs(v1) > vmax) return sg*vmax
- return v1
 end
 
 function ship:update()
  local t = btn(0) and -1 or btn(1) and 1 or 0
  t *= self.thrust
  t = constraints:constrain(self, t)
+ -- t = constraints:constrain(self, t)
+ -- t = constraints:constrain(self, t)
  local s = calc_velocity(self.dx, t, self.maxspd, self.drag)
 
  self.x += s
@@ -165,10 +164,31 @@ constraints = {
 
 function constraints:constrain(s, want)
  self.color=10
+ if (not self.xmin) return want
 
- local v1 = calc_velocity(s.dx, want, s.maxspd, s.drag)
+ -- bmx: brake max
- local bd, bf = brake_dist(v1, s.thrust + s.drag)
+ local v1, bmx = calc_velocity(s.dx, want, s.maxspd, s.drag), s.thrust + s.drag
-
+ local bd, bf = brake_dist(v1, bmx)
+ local bx, txm = s.x + bd + v1, self.xmax
+ if bx < self.xmin then
+  -- predicted brake point left
+  -- of xmin; apply max reverse
+  -- thrust, treat xmin as our
+  -- max target, and handle
+  -- overbraking by coalescing
+  -- with past +xmax case
+  self.color = 9
+  want = s.thrust
+  txm = self.xmin
+  v1 = calc_velocity(s.dx, want, s.maxspd, s.drag)
+  bd, bf = brake_dist(v1, bmx)
+  bx  = bd + s.x + v1
+ end
+ if (bx <= txm) return want
+ self.color = 8
+ local overage = bx - txm
+ want -= overage/max(bf,1)
+ if (want < -s.thrust) want = -s.thrust
  return want
 end