Remove power mechanics. Replace with XP stub.

Also a few random comments and cleanups along the way.

vacuum_gambit.p8

@@ -342,7 +342,7 @@ function drawhud()
  dropshadow("p h",114,59,1)
  inset(114,66,119,125)
  fillp(0x5a5a)
- vertmeter(115,67,118,124,primary_ship.power, primary_ship.max_power, powcols)
+ vertmeter(115,67,118,124,primary_ship.xp, primary_ship.xptarget, powcols)
 
  inset(120,66,125,125)
  -- 57 px vertically
@@ -425,14 +425,9 @@ ship_m = mknew{
  -- ships have no shield by default
  shield = 0,
  maxshield = 0,
- shieldcost = 32767.9,
  shieldcooldown =  0x0.003c,--1s
  shieldpenalty = 0x0.012c, --5s
  
- max_power = 120,
- power = 120,
- generator = 2, -- power gen per frame
- 
  slip = true,  -- most enemies slide
  
  xmomentum = 0,
@@ -492,7 +487,6 @@ 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)
@@ -534,9 +528,7 @@ end
 
 function ship_m:maybe_shoot(gun)
  if (not gun) return
- if (self.power < gun.power) return
- if (not gun:shoot(self.x + self.fire_off_x, self.y + self.fire_off_y)) return
- self.power -= gun.power
+ return gun:shoot(self.x + self.fire_off_x, self.y + self.fire_off_y)
 end
 
 function ship_m:hitship(other)
@@ -577,10 +569,8 @@ end
 function ship_m:refresh_shield()
  if (self.shield >= self.maxshield) return
  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
 
@@ -595,6 +585,28 @@ function enemy_blt_cat()
  return ebullets
 end
 
+-- x, y: position
+-- dx, dy: movement (linear)
+-- f: frames remaining; nil for no limit
+-- sprite: what sprite to draw
+-- hurt -- hurtbox
+-- width, height -- in sprites
+-- x_off, y_off -- how to
+--   initially position relative
+--   to firing point. weird
+--   details, check impl
+-- damage -- damage to do to
+--   a ship that gets hit
+-- category -- function that
+--   returns which bullet list
+--   to spawn onto
+-- hitship -- event handler,
+--   takes ship as argument.
+--   default: die, return true.
+--   returns whether to delete
+--   the bullet
+-- die -- on-removal event,
+--   default no-op
 bullet_base = mknew{ }
 
 gun_base = mknew{ 
@@ -613,7 +625,8 @@ end
 function bullet_base:move()
  self.x += self.dx
  self.y += self.dy
- if (self.y > 128) or (self.y < -8 * self.height) then
+ if (self.f) self.f -= 1
+ if (self.y > 128) or (self.y < -8 * self.height) or (self.f and self.f < 0) then
   self:die()
   return true
  end
@@ -654,7 +667,7 @@ end
 
 zap_e = mknew(bullet_base.new{
  --shape
- sprite = 9, --index of enemy ammo sprite
+ sprite = 9, --index of ammo sprite
  width = 1, --in 8x8 blocks
  height = 1,
  hurt = { -- hurtbox - where this ship can be hit
@@ -683,7 +696,6 @@ zap_p = mknew(zap_e.new{
 })
 
 zap_gun_e = mknew(gun_base.new{
- power = 20, -- power consumed per shot
  cooldown = 0x0.000a, -- frames between shots
  ammo = nil, -- unlimited ammo - main gun
  actually_shoot = spawn_one(zap_e),
@@ -740,7 +752,6 @@ blast = mknew(bullet_base.new{
 
 blast_gun = mknew(gun_base.new{
  icon = 13,
- power = 0, -- only cost is ammo
  cooldown = 0x0.0020, -- frames between shots
  ammo = 5,
  maxammo = 5,
@@ -776,7 +787,6 @@ protron_p = mknew(protron_e.new{
 
 protron_gun_e = mknew(gun_base.new{
  icon = 25,
- power = 60,
  cooldown = 0x0.000f, -- frames between shots
  ammo = nil,
  maxammo = nil,
@@ -838,7 +848,6 @@ vulcan_p = mknew(vulcan_e.new{
 vulcan_gun_e = mknew(gun_base.new{
  icon = 37,
  enemy = false,
- power = 8,
  cooldown = 0x0.0002, -- frames between shots
  ammo = nil,
  maxammo = nil,
@@ -880,13 +889,16 @@ player = mknew(ship_m.new{
  sparkodds = 2,
  boss = true,  -- dramatic special effects
  
- -- health and power
+ -- health
  hp = 3, -- current health, non-regenerating
  maxhp = 3, -- player only; other ships never heal
- shield = 2, -- regenerates, using power
+ shield = 2, -- regenerates
  maxshield = 2,
- shieldcost = 60, -- power cost to refill shield
- generator = 2, 
+
+ -- xp, increments of 0x0.01
+ xp = 0,
+ xptarget = 0x0.05,
+ level = 1,
 
  -- gun
  main_gun = nil, -- assign at spawn time
@@ -942,7 +954,7 @@ frownie = mknew(ship_m.new{
  sparks = smokespark,
  sparkodds = 8,
  
- -- health and power
+ -- health
  hp = 0.5, -- enemy ships need no max hp
 
  -- position
@@ -984,7 +996,6 @@ blocky = mknew(frownie.new{
 
 spewy = mknew(frownie.new{
  sprite=26,
- power=-20,
  hurt = {
   x_off=0,
   y_off=1,
@@ -992,13 +1003,11 @@ spewy = mknew(frownie.new{
   height=5
  },
  hp=0.5,
- maxpower=70,
- generator=0.5,
  fire_off_x=4,
- fire_off_y = 7,
+ fire_off_y=7,
  act=function(self)
   local dx,dy,shoot_spec=frownie.act(self)
-  return dx, dy, shoot_spec, true
+  return dx, dy, shoot_spec, self.y > 10
  end,
  init = function(ship)
   ship.main_gun=ship.main_gun or protron_gun_e.new{}
@@ -1019,7 +1028,6 @@ chasey = mknew(ship_m.new{
  hp = 1.5,
  shield = 1,
  maxshield = 1,
- shieldcost = 180,
 
  fire_off_x = 4,
  fire_off_y = 7,
@@ -1037,7 +1045,7 @@ chasey = mknew(ship_m.new{
 function chasey:act()
  self.xmin = max(primary_ship.x-8, 0)
  self.xmax = min(primary_ship.x + 8, 112 - 8*self.size)
- return 0, 0, false, self.x - 16 < primary_ship.x and self.x + 16 > primary_ship.x
+ return 0, 0, false, self.y > 10 and self.x - 16 < primary_ship.x and self.x + 16 > primary_ship.x
 end
 
 xl_chasey=mknew(chasey.new{
@@ -1455,10 +1463,6 @@ algorithm expressed.
 
 guns
 ----
-* power - cost in generator
-  power to fire. may be 0.
-  field directly read by ships;
-  required in all guns.
 * t - metatable for bullet type.
   fired once in the bullet's
   default direction per shot.
@@ -1486,11 +1490,6 @@ actually_shoot to change
 projectile logic while keeping
 cooldown and ammo logic.
 
-ships manage generator power
-before asking the gun to shoot.
-this behavior is in
-ship_m:maybe_shoot.
-
 bullets
 -------
 * dx, dy - movement per frame.
@@ -1577,39 +1576,19 @@ or less hp calls self:die() and
 tells the main game loop to
 remove it.
 
-ships have power, from 0 to
-ship.maxpower, increasing by
-ship.generator per frame.
-in maybe_shoot, ships check that
-they have power to fire before
-trying to fire (the gun itself
-checks ammo and cooldown), and
-spend that power if they fire.
-
-power is also used to restore
-shields - ship.shieldcost per
-point of shields. shieldcooldown
-is the interval between
-restoring shield points, which
-is reset to shieldpenalty when a
-ship takes damage (regardless of
-whether that damage is stopped
-by the shield or not).
-shieldpenalty is much worse than
-shieldcooldown (hALO shield).
-
-therefore:
-* damaged ships spend power
-  repairing shields, which may
-  affect ability to fire guns.
-  this looks like a slow firing
-  rate because the ship will
-  eventually recover enough
-  energy to fire.
-* a ship firing nonstop will
-  typically be unable to recover
-  any shields because it will
-  not have energy to do so.
+shieldcooldown is the interval
+between restoring shield points.
+shieldpenalty is the delay
+before restoring points after
+any damage, reset to this value
+on every damaging hit (whether
+it is absorbed by the shield or
+not) -- shield behaves like
+halo and other shooters in its
+heritage, where it recovers if
+you avoid damage for a while.
+not that there is any safe cover
+in this kind of game.
 
 ships do not repair hp on their
 own. negative-damage bullets