trig zap gun; fixes

use the trig gun for the zap gun

vacuum_gambit.p8

@@ -874,6 +874,54 @@ function gun_base:shoot(x, y)
  return true
 end
 
+trig_gun = mknew(gun_base.new{
+ veloc = 1,
+ aim = 0.75, -- down; 0.25 is up
+ shot_idx = 0,
+ -- shots: list<list<[3]num>>
+ --  describing a cycling
+ --  firing pattern. shot_idx
+ --  tracks offset into pattern.
+ -- each nested list: a burst
+ --  of shots to fire; takes
+ --  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
+ init = function(self)
+  if (not self.shots) self.shots = {{{0}}}
+ end
+})
+
+function trig_gun:actually_shoot(x, y)
+ local shots,veloc,aim,munition = self.shots,self.veloc,self.aim,self.munition
+ local idx = self.shot_idx % #shots + 1
+ self.shot_idx = idx
+ shots = shots[idx]
+ for s in all(shots) do
+  local a,v,xo = unpack(s)
+  v = v or veloc
+  a += aim
+  -- todo: switch munition
+  --  depending on angle
+  --  (allows for non-round
+  --   sprites and hitboxes on
+  --   shots from guns with
+  --   widely varying angles)
+  local m = munition.new{}
+  -- todo: automatically make
+  -- high velocity shots do
+  -- multiple collision checks
+  m.dy = sin(a) * veloc
+  m.dx = cos(a) * veloc
+  m:spawn_at(x+(xo or 0), y)
+ end
+end
+
+
 -->8
 -- bullets and guns
 
@@ -892,8 +940,6 @@ zap_e = mknew(bullet_base.new{
  y_off = 8,
  
  damage = 1,
- dx = 0,  -- px/frame
- dy = 4,
 
  hitship = const_fxn(true),
 
@@ -902,19 +948,21 @@ zap_e = mknew(bullet_base.new{
 
 zap_p = mknew(zap_e.new{
  sprite = 8,
- dy = -8,
  y_off = 0,
  category = player_blt_cat,
 })
 
-zap_gun_e = mknew(gun_base.new{
+zap_gun_e = mknew(trig_gun.new{
  cooldown = 0x0.0020, -- frames between shots
+ veloc = 4,
  munition = zap_e,
 })
 
 zap_gun_p = mknew(zap_gun_e.new{
  icon = 19,
  munition = zap_p,
+ veloc = 8,
+ aim = 0.25,
  hdr = "mAIN gUN",
 })