vulcan_gun as trig gun

causes x offset to reverse for negative aim; may need to be careful
with how I make aiming guns actually work, but this should work for
deriving player guns from enemy guns (by using negative aim)!

vacuum_gambit.p8

@@ -876,7 +876,7 @@ end
 
 trig_gun = mknew(gun_base.new{
  veloc = 1,
- aim = 0.75, -- down; 0.25 is up
+ aim = 0.75, -- down; 0.25, or -0.75, is up
  shot_idx = 0,
  -- shots: list<list<[3]num>>
  --  describing a cycling
@@ -887,10 +887,10 @@ trig_gun = mknew(gun_base.new{
  --  1 ammo; sequential
  -- each shot: angle (turns,
  --  relative to `aim`),
- --  velocity, firing x-offset;
- --  if velocity is nil, use
- --  self.veloc instead;
- --  if x-offset is nil, use 0
+ --  firing x-offset, velocity;
+ --   if x-offset is nil, use 0;
+ --   if velocity is nil, use
+ --    self.veloc instead
  init = function(self)
   if (not self.shots) self.shots = {{{0}}}
  end
@@ -902,8 +902,11 @@ function trig_gun:actually_shoot(x, y)
  self.shot_idx = idx
  shots = shots[idx]
  for s in all(shots) do
-  local a,v,xo = unpack(s)
+  local a,xo,v = unpack(s)
   v = v or veloc
+  xo = xo or 0
+  -- reverse x-offset for negative base angle
+  if (aim < 0) xo = -xo
   a += aim
   -- todo: switch munition
   --  depending on angle
@@ -1124,48 +1127,37 @@ vulcan_e = mknew(bullet_base.new{
  y_off = 0,
  
  damage = 0.5,
- -- dx from gun
- dy = 2,
  category=enemy_blt_cat
 })
 
 vulcan_p = mknew(vulcan_e.new{
  sprite=22,
  y_off = 4,
- dy = -4,
  category=player_blt_cat
 })
 
-vulcan_gun_e = mknew(gun_base.new{
+vulcan_gun_e = mknew(trig_gun.new{
  icon = 37,
  cooldown = 0x0.0003, -- 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 b = self.munition.new{
-   dx = self.dxs[self.dxidx],
-  }
-  b:spawn_at(self.xoffs[self.dxidx]+x,y)
-  self.dxidx += 1
-  if (self.dxidx > #self.dxs) self.dxidx = 1
- end
+ veloc = 2,
+ shots = {{{0.02, 2}}, {{-0.02,0}}, {{-0.03, -2}}, {{0.03, 2}}, {{0.02, 0}}, {{-0.02, -2}}}
 })
 
 machine_gun_e = mknew(vulcan_gun_e.new{
  icon = 38,
  clip_size = 12,
  clip_interval = 0x0.005a,
- dxs = {0, 0},
- xoffs = {1, -1},
+ shots = {{{0, 2}}, {{0, -2}}}
 })
 
 vulcan_gun_p = mknew(vulcan_gun_e.new{
  munition=vulcan_p,
  maxammo = 100,
+ aim=-0.75,
+ veloc=4,
  hdr = "vULCAN",
  body = [[---------GUN
 
@@ -1880,6 +1872,7 @@ end
 
 -- add a new gun
 function spec_gun_opts()
+ -- todo: avoid duplicates
  return pick(spec_gunt, 2)
 end
 
@@ -1901,7 +1894,6 @@ end
 
 -- ordinary upgrades
 function small_opts()
- -- todo: include gun opts
  if(not primary_ship.special_guns) return pick(primary_ship:small_upgrade_opts(), 2)
  local opts = {rnd(primary_ship:small_upgrade_opts())}
  for g in all(primary_ship.special_guns) do
@@ -1982,7 +1974,10 @@ function rearm_mode:shuffle()
  -- until the upgrade deck
  -- is a thing that exists
  local lev = primary_ship.level + 1
- if lev == 4 or lev == 12 then
+
+ -- for testing: more guns really early
+ -- if lev == 4 or lev == 12 then
+ if lev == 2 or lev == 3 then
   self.options = spec_gun_opts()
  elseif lev % 4 == 0 then
   self.options = big_opts()