fix remaining vulcan-family bug

next step is to pick a real direction -- MMBN-like (+STS-like) or
Survivors-like -- and adapt to match. I am likely to completely remove
the energy system and use permanent autofire, freeing both fire buttons
for more interesting tasks. It loses the opportunity to create a dynamic
around baiting an enemy to keep shooting so its shields don't recover,
but I don't think it loses a lot else.

Either energy management needs to become really important and the game
becomes strategic and tactical, or it needs to be a non-issue and it is
an arcade game. Tyrian itself did not make the energy system interesting
and it was just a tax, so making it interesting would be doing something
new. But I think it's a kind of "interesting" that almost nobody would
adopt unless I go _very hard_ into creating a tactical/strategic shmup.
A shmup that is actually a strange kind of RTS sounds... really cool,
actually, but I'm not at all confident I could design it.

Removing energy entirely gives us a button _and_ a meter back, which
can be used for XP (Survivors-like) or rearm time (MMBN-like).

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
@@ -170,18 +169,26 @@ function constraints:constrain(s, want)
  -- bmx: brake max
  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, self.xmax
+ 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
+  bx  = bd + s.x + v1
  end
- if (bx < txm) return want
+ if (bx <= txm) return want
  self.color = 8
- -- TODO: implement overshot constraint
+ local overage = bx - txm
+ want -= overage/max(bf,1)
+ if (want < -s.thrust) want = -s.thrust
  return want
 end
 

vacuum_gambit.p8

@@ -1,5 +1,5 @@
 pico-8 cartridge // http://www.pico-8.com
-version 41
+version 42
 __lua__
 -- vacuum gambit
 -- by kistaro windrider
@@ -18,6 +18,11 @@ function csv(s)
  end
  return ret
 end
+function const_fxn(x)
+ return function()
+  return x
+ end
+end
 
 -- generate standard "overlay"
 -- constructor for type tt.
@@ -118,7 +123,7 @@ end
 function _init()
  init_blip_pals()
 	wipe_level()
-	primary_ship.main_gun = zap_gun.new()
+	primary_ship.main_gun = zap_gun_p.new()  -- redundant?
 	load_level(example_level_csv)
 	state = game
 	pal(2,129)
@@ -320,6 +325,7 @@ function drawgame()
 end
 
 powcols=split"170,154,153,148,68"
+shlcols = split"204,220,221"
 function drawhud()
  -- 112-and-right is hud zone
  rectfill(112, 0, 127, 127,0x56)
@@ -328,21 +334,30 @@ function drawhud()
  line(113,127)
  
  draw_gun_info("❎",1,116,3,primary_ship.main_gun)
- draw_gun_info("🅾️",2,116,31,primary_ship.special_gun)
+ draw_gun_info("🅾️",1,116,31,primary_ship.special_gun)
  
- dropshadow("pwr",114,59,1)
+ dropshadow("p h",114,59,1)
- inset(114,66,125,92)
+ inset(114,66,119,125)
  fillp(0x5a5a)
- vertmeter(115,67,124,91,primary_ship.power, primary_ship.max_power, powcols)
+ vertmeter(115,67,118,124,primary_ship.power, primary_ship.max_power, powcols)
 
- 
+ inset(120,66,125,125)
- dropshadow("h s",114,97,1)
+ -- 57 px vertically
- inset(114,104,125,125)
+ local mxs, cs, mxh, ch = primary_ship.maxshield, primary_ship.shield, primary_ship.maxhp, primary_ship.hp
- line(119,105,119,124,119)
+ if (mxs > 0) and (mxh > 0) then
- line(120,105,120,125,85)
+  local split = 57 * (mxs / (mxs + mxh)) \ 1 + 66
- vertmeter(115,105,118,124,primary_ship.hp, primary_ship.maxhp, hpcols)
+  line(121, split, 124, split, 0xba)
- vertmeter(121,105,124,124,primary_ship.shield, primary_ship.maxshield,{204,220,221})
+  vertmeter(121,67,124,split-1,cs, mxs,shlcols)
- fillp(0)
+  vertmeter(121,split+1,124,124,ch, mxh, hpcols)
+ elseif mxs > 0 then
+  vertmeter(121,67,124,124,cs,mxs,shlcols)
+ elseif mxh > 0 then
+  vertmeter(121,67,124,124,ch,mxh,hpcols)
+ else
+  print("!", 122, 94, 9)
+  print("!", 121, 93, 8)
+ end
+  fillp(0)
 end
 
 function draw_gun_info(lbl,fgc,x,y,gun)
@@ -368,9 +383,9 @@ function draw_gun_info(lbl,fgc,x,y,gun)
 end
 
 function vertmeter(x0,y0,x1,y1,val,maxval,cols)
- if (val <= 0) return
+ if ((val <= 0) or (maxval <= 0)) return
  local h = y1-y0
- local px = -flr(-(h*val)\maxval)
+ local px = val/maxval * h \ 1
  local ncols = #cols
  local firstcol = ((h-px)*ncols\h)+1
  local lastbottom = y0+(h*firstcol\ncols)
@@ -408,51 +423,86 @@ ship_m = {
  shield = 0,
  maxshield = 0,
  shieldcost = 32767.9,
- shieldcooldown =  0x0.00a0,
+ shieldcooldown =  0x0.003c,--1s
+ shieldpenalty = 0x0.012c, --5s
  
- -- default generator behavior:
+ max_power = 120,
- -- 10 seconds for a full charge
+ power = 120,
- max_power = 600,
+ generator = 2, -- power gen per frame
- power = 600,
- generator = 1, -- power gen per frame
  
  slip = true,  -- most enemies slide
  
  xmomentum = 0,
  ymomentum = 0,
+
+ -- xmin, xmax, ymin, ymax:
+ --   movement constraints
+ --   enforced by `constrain`.
+ xmin = 0, xmax = 104,
+ -- ymin, ymax default to nil
+ --   pship needs more constraint 
 }
 mknew(ship_m)
 
 function ship_m:die()
  self.dead = true
- if (self.hp <= 0) boom(self.x+self.size*4, self.y+self.size*4,12*self.size, self.boss)
+ if (self.hp < 0) boom(self.x+self.size*4, self.y+self.size*4,12*self.size, self.boss)
+end
+
+function ship_m:calc_velocity(v0, t)
+ v0 = mid(v0 + t, self.maxspd, -self.maxspd)
+ return v0 - mid(self.drag, -self.drag, v0)
+end
+
+function ship_m:brake_dist(v0)
+ local brake_max = self.thrust + self.drag
+ local tri_frames = abs(v0\brake_max)
+ local chunks = tri_frames * (tri_frames - 1) >> 1
+ local chunk_zone = chunks * brake_max
+ local overage = abs(v0) - tri_frames * brake_max
+ return (chunk_zone + overage * (tri_frames + 1)) * sgn(v0), (overage > 0) and tri_frames + 1 or tri_frames
+end
+
+function ship_m:constrain(p, dp, pmin, pmax, want)
+ if (not pmin) return want
+ local v1, bd, bf, bp
+ function calc_targets()
+  -- velocity after move
+  v1 = self:calc_velocity(dp, want)
+  -- brake distance and frames
+  bd, bf = self:brake_dist(v1)
+  -- brake point
+  bp = p + bd + v1
+ end
+ calc_targets()
+ if bp < pmin then
+  -- undershoot. max thrust,
+  -- then treat as overshoot
+  -- targeting minimum bound
+  want, pmax = self.thrust, pmin
+  calc_targets()
+ end
+ if (bp <= pmax) return want
+ -- spread overshoot across frames
+ want -= (bp - pmax)/max(bf,1)
+ return max(want, -self.thrust)
 end
 
 function ship_m:move()
  self:refresh_shield()
  self.power = min(self.max_power, self.power + self.generator)
  local dx, dy, shoot_spec, shoot_main = self:act()
+ dx = self:constrain(self.x, self.xmomentum, self.xmin, self.xmax, dx)
+ dy = self:constrain(self.y, self.ymomentum, self.ymin, self.ymax, dy)
  if (shoot_main) self:maybe_shoot(self.main_gun)
  if (shoot_spec) self:maybe_shoot(self.special_gun)
  if (dx ~= 0 or dy ~= 0) spark(self.sparks, self.x + 4*self.size, self.y + 4*self.size, dx*2.5, dy*2.5, self.sparkodds)
- self.xmomentum += dx
+ self.xmomentum = self:calc_velocity(self.xmomentum, dx)
- self.ymomentum += dy
+ self.ymomentum = self:calc_velocity(self.ymomentum, dy)
- self.xmomentum = mid(-self.maxspd, self.maxspd, self.xmomentum)
- self.ymomentum = mid(-self.maxspd, self.maxspd, self.ymomentum)
 
  self.x += self.xmomentum
  self.y += self.ymomentum
  
- if self == primary_ship then
-  self.x = mid(0, 112 - 8 * self.size, self.x)
-  self.y = mid(0, 128 - 8 * self.size, self.y)
- end
- 
- --friction
- local d = self.drag
- self.xmomentum -= mid(d, -d, self.xmomentum)
- self.ymomentum -= mid(d, -d, self.ymomentum)
- 
  -- "scrolling" behavior
  if self.slip then
   self.y += scrollrate
@@ -497,7 +547,7 @@ end
 
 function ship_m:hitsomething(dmg)
  if (dmg <= 0) return false
- self.shield_refresh_ready = lframe + self.shieldcooldown
+ self.shield_refresh_ready = lframe + self.shieldpenalty
  if self.shield >= dmg then
   self.shield -= dmg
   self:ow(true)
@@ -506,7 +556,7 @@ function ship_m:hitsomething(dmg)
  dmg -= self.shield
  self.shield = 0
  self.hp -= dmg
- if self.hp <= 0 then
+ if self.hp < 0 then
   self:die()
   return true
  end
@@ -527,6 +577,7 @@ function ship_m:refresh_shield()
  if (lframe < self.shield_refresh_ready) return
  if (self.power < self.shieldcost) return
  self.shield += 1
+ self.shield = min(self.shield, self.maxshield)
  self.power -= self.shieldcost
  self.shield_refresh_ready = lframe + self.shieldcooldown
 end
@@ -534,9 +585,15 @@ end
 -->8
 -- bullet and gun behaviors
 
-bullet_base = {
+function player_blt_cat()
- enemyspd = 0.5
+ return pbullets
-}
+end
+
+function enemy_blt_cat()
+ return ebullets
+end
+
+bullet_base = { }
 mknew(bullet_base)
 
 gun_base = { 
@@ -555,18 +612,10 @@ end
 
 function bullet_base:move()
  self.x += self.dx
- if self.enemy then
+ self.y += self.dy
-  self.y += self.dy
+ if (self.y > 128) or (self.y < -8 * self.height) then
-  if self.y > 128 then
+  self:die()
-   self:die()
+  return true
-   return true
-  end
- else
-  self.y -= self.dy
-  if self.y < -8*self.height then
-   self:die()
-   return true
-  end
  end
  return false
 end
@@ -575,19 +624,20 @@ function bullet_base:draw()
  spr(self.sprite, self.x, self.y, self.width, self.height)
 end
 
-function bullet_base:spawn_at(x, y)
+-- An `actually_shoot` factory
- self.x = x - self.center_x_off
+-- for trivial guns
- if self.enemy then
+function spawn_one(t)
-  self.dx *= self.enemyspd
+ return function(gun, x, y)
-  self.dy *= self.enemyspd
+  t.new{}:spawn_at(x, y)
-  self.y = y + self.top_y_off
-  ebullets:push_back(self)
- else
-  self.y = y - (8 * self.height) + self.bottom_y_off
-  pbullets:push_back(self)
  end
 end
 
+function bullet_base:spawn_at(x, y)
+ self.x = x - self.x_off
+ self.y = y - self.y_off
+ self.category():push_back(self)
+end
+
 function gun_base:shoot(x, y)
  if (lframe < self.shoot_ready) return false
  if self.ammo then
@@ -599,23 +649,12 @@ function gun_base:shoot(x, y)
  return true
 end
 
-function gun_base:actually_shoot(x, y)
- local typ = self.t
- local b = typ.new{
-  enemy = self.enemy,
-  sprite = self.enemy and typ.esprite or typ.psprite,
- }
- b:spawn_at(x, y)
- return true
-end
-
 -->8
 -- bullets and guns
 
-zap = bullet_base.new{
+zap_e = bullet_base.new{
  --shape
- psprite = 8, --index of player ammo sprite
+ sprite = 9, --index of enemy ammo sprite
- esprite = 9, -- index of enemy ammo sprite
  width = 1, --in 8x8 blocks
  height = 1,
  hurt = { -- hurtbox - where this ship can be hit
@@ -624,33 +663,43 @@ zap = bullet_base.new{
   width = 2,
   height = 8
  },
- center_x_off = 1, -- how to position by ship
+ x_off = 1, -- how to position by ship
- bottom_y_off = 0,
+ y_off = 8,
- top_y_off = 0,
  
  damage = 1,
  dx = 0,  -- px/frame
- dy = 8,
+ dy = 4,
 
- hitship = function(_, _)
+ hitship = const_fxn(true),
-  return true
+
- end
+ category = enemy_blt_cat,
 }
-mknew(zap)
+mknew(zap_e)
 
-zap_gun = gun_base.new{
+zap_p = zap_e.new{
- enemy = false,
+ sprite = 8,
+ dy = -8,
+ y_off = 0,
+ category = player_blt_cat,
+}
+mknew(zap_p)
+
+zap_gun_e = gun_base.new{
  power = 20, -- power consumed per shot
  cooldown = 0x0.000a, -- frames between shots
  ammo = nil, -- unlimited ammo - main gun
- t = zap -- metatable of bullet to fire
+ actually_shoot = spawn_one(zap_e),
 }
-mknew(zap_gun)
+mknew(zap_gun_e)
+
+zap_gun_p = zap_gun_e.new{
+ actually_shoot = spawn_one(zap_p),
+}
+mknew(zap_gun_p)
 
 blast = bullet_base.new{
  --shape
- psprite = 12, --index of player ammo sprite
+ sprite = 12, --index of player ammo sprite
- esprite = 3, -- index of enemy ammo sprite
  width = 1, --in 8x8 blocks
  height = 1,
  hurt = { -- hurtbox - where this ship can be hit
@@ -659,13 +708,12 @@ blast = bullet_base.new{
   width = 6,
   height = 6
  },
- center_x_off = 4, -- how to position by ship
+ x_off = 4, -- how to position by ship
- bottom_y_off = 0,
+ y_off = 0,
- top_y_off = 0,
  
  damage = 4,
  dx = 0,  -- px/frame
- dy = 2,
+ dy = -2,
  awaitcancel = false,
 
  -- disable damage for 2 frames
@@ -690,25 +738,24 @@ blast = bullet_base.new{
     self.awaitcancel = false
    end)
   end
- end
+ end,
+ category=player_blt_cat
 }
 mknew(blast)
 
 blast_gun = gun_base.new{
  icon = 13,
- enemy = false,
+ power = 0, -- only cost is ammo
- power = 0, -- ammo, not power
  cooldown = 0x0.0020, -- frames between shots
  ammo = 5,
  maxammo = 5,
- t = blast -- type of bullet to fire
+ actually_shoot = spawn_one(blast),
 }
 mknew(blast_gun)
 
-protron = bullet_base.new{
+protron_e = bullet_base.new{
  --shape
- psprite = 23, --index of player ammo sprite
+ sprite = 24,
- esprite = 24, -- index of enemy ammo sprite
  width = 1, --in 8x8 blocks
  height = 1,
  hurt = { -- hurtbox - where this ship can be hit
@@ -717,56 +764,63 @@ protron = bullet_base.new{
   width = 2,
   height = 2
  },
- center_x_off = 1, -- how to position by ship
+ x_off = 1, -- how to position by ship
- bottom_y_off = 4,
+ y_off = 4,
- top_y_off = 0,
  
  damage = 1,
- dx = 0,  -- px/frame
+ dym = 0.5, -- gun sets dy;
- dy = 3,
+             -- this is mult
+ category = enemy_blt_cat,
 }
-mknew(protron)
+mknew(protron_e)
 
-protron_gun = gun_base.new{
+protron_p = protron_e.new{
+ sprite=23,
+ dym = -1,
+ y_off = 0,
+ category=player_blt_cat,
+}
+mknew(protron_p)
+
+protron_gun_e = gun_base.new{
  icon = 25,
- enemy = false,
+ power = 60,
- power = 35,
  cooldown = 0x0.000f, -- frames between shots
  ammo = nil,
  maxammo = nil,
- actually_shoot = function(self, x, y)
+ munition = protron_e
-  local sprite = protron.psprite
-  if (self.enemy) sprite=protron.esprite
-  for i=1,3 do
-   local b = protron.new{
-    enemy=self.enemy,
-    sprite=sprite,
-    dx = i,
-    dy = 4-i
-   }
-   b:spawn_at(x,y)
-   local b2 = protron.new{
-    enemy=self.enemy,
-    sprite=sprite,
-    dx = -i,
-    dy = 4-i
-   }
-   b2:spawn_at(x,y)
-  end
-  local bup = protron.new{
-   enemy=self.enemy,
-   sprite=sprite,
-   dy=4
-  }
-  bup:spawn_at(x,y)
- end
 }
-mknew(protron_gun)
+mknew(protron_gun_e)
 
-vulcan = bullet_base.new{
+function protron_gun_e:actually_shoot(x, y)
+ local m = self.munition.dym
+ for i=1,3 do
+  local b = self.munition.new{
+   dx = i*m,
+   dy = (4-i)*m,
+  }
+  b:spawn_at(x,y)
+  local b2 = self.munition.new{
+   dx = -i*m,
+   dy = (4-i)*m,
+  }
+  b2:spawn_at(x,y)
+ end
+ local bup = self.munition.new{
+  dx=0,
+  dy=4*m,
+ }
+ bup:spawn_at(x,y)
+end
+
+protron_gun_p = protron_gun_e.new{
+ munition = protron_p,
+}
+mknew(protron_gun_p)
+
+vulcan_e = bullet_base.new{
  --shape
- psprite = 22, --index of player ammo sprite
+ sprite = 21,
- esprite = 21, -- index of enemy ammo sprite
  width = 1, --in 8x8 blocks
  height = 1,
  hurt = { -- hurtbox - where this ship can be hit
@@ -775,31 +829,37 @@ vulcan = bullet_base.new{
   width = 1,
   height = 4
  },
- center_x_off = 0.5, -- how to position by ship
+ x_off = 0.5, -- how to position by ship
- bottom_y_off = 4,
+ y_off = 0,
- top_y_off = 0,
  
  damage = 0.5,
- dx = 0,  -- px/frame
+ -- dx from gun
- dy = 4,
+ dy = 2,
+ category=enemy_blt_cat
 }
-mknew(vulcan)
+mknew(vulcan_e)
 
-vulcan_gun = gun_base.new{
+vulcan_p = vulcan_e.new{
+ sprite=22,
+ y_off = 4,
+ dy = -4,
+ category=player_blt_cat
+}
+mknew(vulcan_p)
+
+vulcan_gun_e = gun_base.new{
  icon = 37,
  enemy = false,
  power = 8,
  cooldown = 0x0.0002, -- frames between shots
  ammo = nil,
  maxammo = nil,
+ munition=vulcan_e,
  dxs = {0.35, -0.35, -0.7, 0.7, 0.35, -0.35},
  xoffs = {1, 0, -1, 1, 0, -1},
  dxidx = 1,
  actually_shoot = function(self, x, y)
-  local sprite = self.enemy and vulcan.esprite or vulcan.psprite
+  local b = self.munition.new{
-  local b = vulcan.new{
-   enemy=self.enemy,
-   sprite=sprite,
    dx = self.dxs[self.dxidx],
   }
   b:spawn_at(self.xoffs[self.dxidx]+x,y)
@@ -807,7 +867,12 @@ vulcan_gun = gun_base.new{
   if (self.dxidx > #self.dxs) self.dxidx = 1
  end
 }
-mknew(vulcan_gun)
+mknew(vulcan_gun_e)
+
+vulcan_gun_p = vulcan_gun_e.new{
+ munition=vulcan_p,
+}
+mknew(vulcan_gun_p)
 
 -->8
 --ships, including player
@@ -834,8 +899,8 @@ player = ship_m.new{
  maxhp = 3, -- player only; other ships never heal
  shield = 2, -- regenerates, using power
  maxshield = 2,
- shieldcost = 300, -- power cost to refill shield
+ shieldcost = 60, -- power cost to refill shield
- generator = 1.5,  -- 1 feels too slow
+ generator = 2, 
 
  -- gun
  main_gun = nil, -- assign at spawn time
@@ -850,6 +915,7 @@ player = ship_m.new{
  ymomentum = 0,
  maxspd = 2.5, -- momentum cap
  thrust = 0.25, -- momentum added from button
+ ymin = 0, ymax = 120, -- stay on screen
  drag = 0.125, -- momentum lost per frame
  slip = false, -- does not slide down screen
  act = function(self)  -- fetch buttons
@@ -868,7 +934,13 @@ player = ship_m.new{
 }
 mknew(player,
  function(p)
-  p.main_gun = zap_gun.new()
+  p.main_gun = zap_gun_p.new()
+  -- ONE HIT MODE
+  --
+  -- p.hp = 0
+  -- p.maxhp = 0
+  -- p.shield = 0
+  -- p.maxshield = 0
  end
 )
 
@@ -886,7 +958,7 @@ frownie = ship_m.new{
  sparkodds = 8,
  
  -- health and power
- hp = 1, -- enemy ships need no max hp
+ hp = 0.5, -- enemy ships need no max hp
 
  -- position
  x=60, -- x and y are for upper left corner
@@ -908,7 +980,7 @@ mknew(frownie)
 
 blocky = frownie.new{
  sprite = 10,
- hp = 2,
+ hp = 1.5,
  hurt = {
   x_off = 0,
   y_off = 0,
@@ -917,7 +989,7 @@ blocky = frownie.new{
  },
  
  ow = function(self)
-  if self.hp <= 1 then
+  if self.hp < 1 then
    self.sprite = 11
   else
    self.sprite = 10
@@ -936,7 +1008,7 @@ spewy = frownie.new{
   width=8,
   height=5
  },
- hp=1,
+ hp=0.5,
  maxpower=70,
  generator=0.5,
  fire_off_x=4,
@@ -947,7 +1019,7 @@ spewy = frownie.new{
  end
 }
 mknew(spewy, function(ship)
- ship.main_gun=ship.main_gun or protron_gun.new{enemy=true}
+ ship.main_gun=ship.main_gun or protron_gun_e.new{enemy=true}
 end)
 
 chasey = ship_m.new{
@@ -961,7 +1033,7 @@ chasey = ship_m.new{
  },
  sparks = smokespark,
  sparkodds = 8,
- hp = 2,
+ hp = 1.5,
  shield = 1,
  maxshield = 1,
  shieldcost = 180,
@@ -975,14 +1047,13 @@ chasey = ship_m.new{
  slip = true,
 }
 mknew(chasey, function(ship)
- ship.main_gun=ship.main_gun or zap_gun.new{enemy=true}
+ ship.main_gun=ship.main_gun or zap_gun_e.new{}
 end)
 
 function chasey:act()
- local dx = 0
+ self.xmin = max(primary_ship.x-8, 0)
- if (self.x < primary_ship.x) dx=self.thrust
+ self.xmax = min(primary_ship.x + 8, 112 - 8*self.size)
- if (self.x > primary_ship.x) dx=-self.thrust
+ return 0, 0, false, self.x - 16 < primary_ship.x and self.x + 16 > primary_ship.x
- return dx, 0, false, self.x - 16 < primary_ship.x and self.x + 16 > primary_ship.x
 end
 
 xl_chasey=chasey.new{
@@ -994,7 +1065,9 @@ xl_chasey=chasey.new{
   width = 12,
   height = 10
  },
- hp = 20,
+ fire_off_x = 8,
+ fire_off_y = 15,
+ hp = 19.5,
  shield = 5,
  boss = true,
  slip = false,
@@ -1010,7 +1083,7 @@ xl_chasey=chasey.new{
  end,
 }
 mknew(xl_chasey, function(ship)
- ship.main_gun=ship.main_gun or zap_gun.new{enemy=true}
+ ship.main_gun=ship.main_gun or zap_gun_e.new{}
 end)
 -->8
 -- collisions
@@ -1219,9 +1292,9 @@ end
 
 function spawn_bonus_vulcan_chasey()
  local c = spawn_chasey()
- c.main_gun=vulcan_gun.new{enemy=true}
+ c.main_gun=vulcan_gun_e.new{enemy=true}
  c.die = function(self)
-  spawn_main_gun_at(self.x-1, self.y-1, vulcan_gun)
+  spawn_main_gun_at(self.x-1, self.y-1, vulcan_gun_p)
   chasey.die(self)
  end
  c.sprite=4
@@ -1324,7 +1397,7 @@ example_level_csv=[[1,spawn_frownie
 310,spawn_blocking_blocky
 310,spawn_blocking_blocky
 311,spawn_frownie
-350,spawn_main_gun_at,70,-11,protron_gun
+350,spawn_main_gun_at,70,-11,protron_gun_p
 401,spawn_frownie
 420,spawn_blocking_frownie
 430,spawn_bonus_vulcan_chasey
@@ -1434,8 +1507,9 @@ bullets
   shots much easier to dodge
 * damage - damage per hit;
   used by ships
-* psprite, esprite - index of
+* sprite - sprite index.
-  player or enemy sprite.
+* x_off, y_off - renamed for
+  the next two vars. may revert
 * center_off_x - the horizontal
   centerpoint of the bullet,
   for positioning when firing.
@@ -1522,10 +1596,12 @@ shields - ship.shieldcost per
 point of shields. shieldcooldown
 is the interval between
 restoring shield points, which
-is reset when a ship takes
+is reset to shieldpenalty when a
-damage (regardless of whether
+ship takes damage (regardless of
-that damage is stopped by the
+whether that damage is stopped
-shield or not).
+by the shield or not).
+shieldpenalty is much worse than
+shieldcooldown (hALO shield).
 
 therefore:
 * damaged ships spend power
@@ -1822,7 +1898,7 @@ powerup = bullet_base.new{
  -- easy to pick up
  dx = 0,
  dy = 1.5, -- 0.75 after enemyspd
- enemy = true, -- collides with player ship
+ category = enemy_blt_cat, -- collides with player ship
  damage = 0,
  
  anim_speed = 2,
@@ -1855,9 +1931,8 @@ repair = powerup.new{
   width = 12,
   height = 12
  },
- center_x_off = 4,
+ x_off = 4,
- top_y_off = 0,
+ y_off = 0,
- bottom_y_off = 0,
  sprites = sheen8x8,
  hitship = function(self, ship)
   if (ship ~= primary_ship) return false
@@ -1883,9 +1958,8 @@ gun_swap = powerup.new{
   height = 16
  },
  -- gun = gun_type.new{}
- center_x_off = 6,
+ x_off = 6,
- top_y_off = 0,
+ y_off = 0,
- bottom_y_off = 4,
  width = 2,
  height = 2,
  sprites = {64, 66, 68, 70, 72, 74, 76, 78},