fix shield crash

now the bounce animation feels like it takes too long, trying to fix it

old_readme.md

@@ -0,0 +1,356 @@
+This file contains text that used to be in the cartridge itself, but
+I'm getting increasingly anxious about cartridge space so I'm moving
+it out ot a separate file.
+
+---
+
+main loop sequence
+==================
+1. level_frame
+2. events
+3. merge new_events into events
+4. update bg intangibles
+5. move ships (player first)
+6. move bullets (player first)
+7. calculate collisions
+ 1. pship on eship
+ 2. ebullet on pship
+ 3. pbullet on eship
+8. update fg intangibles
+9. check for end of level
+
+draw order
+----------
+bottom to top:
+1. intangibles_bg
+2. player bullets
+3. player ships
+4. enemy ships
+5. enemy bullets
+6. intangibles_fg
+
+notes
+-----
+intangibles_fg move()s after
+all collisions and other moves
+are processed. if an intangible
+is added to the list as a result
+of a collision or move, it will
+itself be move()d before it is
+drawn.
+
+data-driven items
+=================
+guns and bullets both allow the
+most common behaviors to be
+expressed with data alone.
+ships only need a movement
+algorithm expressed.
+
+guns
+----
+* t - metatable for bullet type.
+  fired once in the bullet's
+  default direction per shot.
+* enemy - if true, fired bullets
+  are flagged as enemy bullets.
+* icon - sprite index of an
+  8x8 sprite to display in the
+  hud when the player has this
+  gun. default is 20, a generic
+  crosshair bullseye thing.
+* cooldown - min frames between
+  shots.
+* ammo, maxammo - permitted
+  number of shots. 0 is empty
+  and unfireable. maxammo = 0
+  will cause a divide by zero
+  so don't do that. if nil,
+  ammo is infinite.
+
+default guns manage ammo and
+cooldown in shoot, then call
+actually_shoot to create the
+projectile. override only
+actually_shoot to change
+projectile logic while keeping
+cooldown and ammo logic.
+
+bullets
+-------
+* dx, dy - movement per frame.
+  player bullets use -dy
+  instead.
+* enemyspd - multiplier for dx
+  and dy on enemy bullets.
+  default is 0.5, making enemy
+  shots much easier to dodge
+* damage - damage per hit;
+  used by ships
+* sprite - sprite index.
+* 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.
+  assume a pixel's coordinates
+  refer to the upper left corner
+  of the pixel; the center of
+  a 2-width bullet with an
+  upper left corner at 0 is 1,
+  not 0.5.
+* top_off_y, bottom_off_y -
+  also for positioning when
+  firing. positive distance from
+  top or bottom edge to image.
+  top_off_y will usually be 0,
+  bottom_off_y will not be when
+  bullets are smaller than
+  the sprite box.
+* width, height - measured in
+  full sprites (8x8 boxes), not
+  pixels. used for drawing.
+
+bullets despawn when above or
+below the screen (player or
+enemy bullets, respectively).
+
+by default, bullets despawn
+when they hit something.
+override hitship to change this.
+
+ships
+____
+
+ships move by calculating
+momentum, then offsetting their
+position by that momentum, then
+clamping their position to the
+screen (horizontally only for
+ships that autoscroll). ships
+that autoscroll (slip==true)
+then slide down by scrollspeed.
+fractional coordinates are ok.
+after movement, ships lose
+momentum (ship.drag along each
+axis). abs(momentum) can't
+exceed ship.maxspeed.
+
+ships gain momentum by acting
+like a player pushing buttons.
+the player ship actually reads
+buttons for this.
+
+act -- returns new acceleration:
+dx, dy, shoot_spec, shoot_main.
+dx and dy are change in momentum
+in px/frame. this is controls
+only -- friction is handled in
+ship:move (`drag` value).
+
+ships hitting another ship take
+1 damage per frame of overlap.
+ships hitting a bullet check
+bullet.damage to find out how
+much damage they take. damage
+is applied to shields, then hp.
+damaged ships flash briefly -
+blue (12) if all damage was
+shielded, white (7) if hp was
+damaged. a ship that then has 0
+or less hp calls self:die() and
+tells the main game loop to
+remove it.
+
+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
+are treated as 0, but a bullet
+can choose to repair the ship
+it hits in its own hitship
+method, or otherwise edit it
+(changing weapons, refilling
+weapon ammo). powerups are
+therefore a kind of bullet.
+
+levels
+======
+
+a level is a table mapping
+effective frame number to
+functions. when a level starts,
+it sets lframe ("level frame")
+and distance to 0.
+
+every frame, level_frame
+increments lframe by 0x0.0001.
+then if the level is not frozen,
+it increments distance by 1.0
+and runs the function in the
+level table for exactly that
+frame number (if any). distance
+is therefore "nonfrozen frames",
+and is used to trigger level
+progress. lframe always
+increments. ships are encouraged
+to use lframe to control
+animation and movement, and may
+use distance to react to level
+progress separately from overall
+time. remember to multiply
+lframe-related stuff by 0x0001.
+
+a special sentinel value, eol,
+marks the end of the level.
+(the level engine doesn't know
+when it's out of events, so
+without eol, the level will
+simply have no events forever.)
+when it finds eol, level_frame
+throws away the current level
+and tells the main loop that it
+might be done. the main loop
+agrees the level is over and the
+player has won when the level
+has reached eol and there are
+no more enemy ships, enemy
+bullets, or background events
+remaining. player ships, player
+bullets, and intangibles are
+not counted.
+
+level freezing
+--------------
+the level is frozen when the
+global value freeze > 0.
+generally, something intending
+to block level progress (a
+miniboss, a minigame, etc.)
+increments freeze and prepares
+some means of decrementing it
+when it no longer wants to block
+level progress.
+
+most commonly, we want to block
+until some specific ship or
+group of ships has died. for
+these ships, override ship:die
+to decrement freeze. make sure
+to set ship.dead in any new
+ship:die method so anything else
+looking at it can recognize
+the ship as dead.
+
+for anything else, you probably
+want an event to figure out when
+to unfreeze.
+
+levels start at 1
+-----------------
+
+distance is initialized to 0
+but gets incremented before the
+first time the engine looks for
+events. therefore, the first
+frame of the level executes
+level[1]. since levelframe
+executes before anything else,
+level[1] sets up the first frame
+drawn in the level. the player
+does not see a blank world
+before level[1] runs.
+level[1] can therefore be used
+to reconfigure the player ship,
+set up backgrounds, start music,
+kick off some kind of fade-in
+animation, etc.
+
+
+events
+======
+the global list "events" stores
+0-argument functions which are
+called every frame. if they
+return true, they are removed
+from the list and not run again;
+if they return false, they stay
+and will be called in later
+frames. the level does not end
+while the events table is
+nonempty.
+
+events are most commonly used
+to set up something for later
+(for example, blip uses an event
+to remove the fx_pallete from
+the flashing ship when the blip
+expires), but can also be used
+to implement a "level within a
+level" that does something
+complicated until it's done. if
+you froze the level when
+creating the event, remember
+to thaw it (freeze -= 1) on all
+paths that return true.
+
+to do complex stuff in events,
+use a closure or a metatable
+that specifies __call.
+
+to avoid editing the events
+list while it is being iterated,
+events that create new events
+must add those events to
+new_events rather than events.
+new_events is only valid during
+the "event execution" stage, so
+events created at any other time
+must go directly on events
+without using new_events.
+
+intangibles
+===========
+
+the intangibles_fg and
+intangibles_bg lists contain
+items with :move and :draw.
+like ships and bullets, they
+move during _update60 and
+draw during _draw. they are
+not checked for collisions.
+
+intangibles_bg moves/draws
+before anything else moves or
+draws. intangibles_fg
+moves/draws last. this controls
+whether your intangible object
+draws in front of or behind
+other stuff. you probably want
+intangibles_bg for decorative
+elements and intangibles_fg
+for explosions, score popups,
+etc.
+
+there's no scrolling background
+engine but intangibles_bg could
+be used to create one, including
+using the map (otherwise unused
+in this engine) for the purpose.
+
+intangibles do not prevent the
+level from ending. like bullets
+and ships, if :move returns
+true, they are dropped.

rearm_prototype.p8

@@ -0,0 +1,223 @@
+pico-8 cartridge // http://www.pico-8.com
+version 42
+__lua__
+-- vacuum gambit
+-- by kistaro windrider
+
+-- stdlib
+
+-- generate standard "overlay"
+-- constructor for type tt.
+-- if tt.init is defined, generated
+-- new calls tt.init(ret) after
+-- ret is definitely not nil,
+-- before calling setmetatable.
+-- use to initialize mutables.
+--
+-- if there was a previous new,
+-- it is invoked on the new
+-- object *after* more, because
+-- this works better with the
+-- `more` impls i use.
+function mknew(tt)
+ local mt,oldnew,more = {__index=tt},tt.new,rawget(tt, "init")
+ tt.new=function(ret)
+  if(not ret) ret = {}
+  if(more) more(ret)
+  if(oldnew) oldnew(ret)
+  setmetatable(ret, mt)
+  return ret
+ end
+ return tt
+end
+
+function easeoutbounce(t)
+	local n1=7.5625
+	local d1=2.75
+
+	if (t<1/d1) then
+		return n1*t*t;
+	elseif(t<2/d1) then
+		t-=1.5/d1
+		return n1*t*t+.75;
+	elseif(t<2.5/d1) then
+		t-=2.25/d1
+		return n1*t*t+.9375;
+	else
+		t-=2.625/d1
+		return n1*t*t+.984375;
+	end
+end
+
+-->8
+-- entry points
+function _draw()
+ cls()
+ draw_hud_placeholder()
+ left_pane:draw()
+ right_pane:draw()
+ rearm_pane_instance:draw()
+end
+
+function _init()
+ item=1
+ bfm=1
+ crt_frm = 1
+ left_pane = weapon_pane.new{}
+ right_pane = weapon_pane.new{
+  is_left=false,
+  s = 2,
+  hdr = "vulc",
+  body = "   rate\n\n  faster\n  firing\n   rate",
+  hot = function() return item == 2 end}
+ rearm_pane_instance = rearm_pane.new{hot=function() return item < 0 end}
+end
+
+function _update60()
+ crt_frm += 0.25
+ if (crt_frm >= 9) crt_frm = 1
+ if (btn(3) and item > 0 or btn(2) and item < 0) item = -item
+ if (btn(0)) item = 1
+ if (btn(1)) item = 2
+ if (btn() & 0xF ~= 0) and bfm >= 10 or bfm >= 30 then
+  bfm = 1
+ else
+  bfm += 1
+ end
+
+ if btnp(4) then
+  left_pane.pos = -1
+  right_pane.pos = -1
+  rearm_pane_instance.pos = -1
+ end
+
+ if btnp(5) then 
+  left_pane.pos = 1
+  right_pane.pos = 1
+  rearm_pane_instance.pos = 1
+ end
+
+ left_pane:update()
+ right_pane:update()
+ rearm_pane_instance:update()
+end
+
+function draw_hud_placeholder()
+ rectfill(112, 0, 127, 127,0x56)
+ rect(112,0,127,127,7)
+ line(127,1,127,127,5)
+ line(113,127)
+end
+
+-->8
+-- rearm pane drawing
+
+crt={-91,-166,-2641,-1441,-23041,23295,-20491,24570}
+
+function glow_box(x0, y0, x1, y1, c, cf)
+ for i,v in ipairs{c[1],c[2],c[1],0} do
+  i -= 1
+  rect(x0+i,y0+i,x1-i,y1-i,v)
+ end
+ fillp(crt[crt_frm&0xff])
+ rectfill(x0+4, y0+4, x1-4, y1-4, cf)
+ fillp()
+end
+
+function frame_col(hot)
+ if (not hot) return {4,10}
+ if (bfm<=16) return {14,7}
+ return {2,8}
+end
+
+function draw_weap_opt(x, y, c, s, hdr, body)
+ camera(-x,-y)
+ glow_box(0,0,55,100,c,1)
+ spr(s,5, 5)
+ print(hdr, 13, 8, 7)
+ print(body, 5, 15, 6)
+ camera()
+end
+
+function draw_rearm(c)
+ glow_box(0,101,111,127,c,1)
+ spr(5,15,107,4,2)
+ print("full ammo\nfull shield\n+50% health",54, 106, 6)
+end
+
+-->8
+-- rearm pane objects
+easing_pane = mknew{
+ -- to enter: pos = -1; to exit: pos = 1
+ -- runs for 32 frames in, 16 frames out
+}
+
+function easing_pane:frac()
+ local pos = self.pos
+ if (not pos) return
+ if (pos < 0) return 1-easeoutbounce(1+pos)
+ if (pos > 0) return (1-pos)*(1-pos)
+ return 0
+end
+
+function easing_pane:update()
+ local pos = self.pos
+ if (not pos or pos == 0) return
+ if (pos < 0) pos = min(pos + 0x0.05, 0)
+ if pos > 0 then
+  pos -= 0x0.1
+  if (pos <= 0) pos = nil
+ end
+ self.pos = pos
+end
+
+weapon_pane = mknew(easing_pane.new{
+ is_left = true,
+ s = 1,
+ hdr = "hull",
+ body = "\n    +1\n   max\n  health",
+ hot = function() return item == 1 end,
+})
+
+function weapon_pane:draw()
+ local frac, is_left = self:frac(), self.is_left
+ if (not frac) return
+ camera(
+  frac * (is_left and 55 or -128) + (1-frac) * (is_left and 0 or -56),
+  0)
+ glow_box(0,0,55,100,frame_col(self:hot()),1)
+ spr(self.s,5, 5)
+ print(self.hdr, 13, 8, 7)
+ print(self.body, 5, 15, 6)
+ camera()
+end
+
+rearm_pane = mknew(easing_pane.new{})
+
+function rearm_pane:draw()
+ local frac = self:frac()
+ if (not frac) return
+ camera(0, -28 * frac)
+ glow_box(0,101,111,127,frame_col(self:hot()),1)
+ spr(5,15,107,4,2)
+ print("full ammo\nfull shield\n+50% health",54, 106, 6)
+ camera()
+end
+
+__gfx__
+000000000b00000000000a0007700770000aa0000444440004444444000000000000000000000000000000000000000000000000000000000000000000000000
+00000000bba80880000008000aa00aa00a0880a0447777700477777a000000000000000000000000000000000000000000000000000000000000000000000000
+007007000aaa28780a0000000990099008000080477aaa7a0477aaaa000000000000000000000000000000000000000000000000000000000000000000000000
+0007000008a8887808000000099009900080080047a0047a047a0000000000000000000000000000000000000000000000000000000000000000000000000000
+00007000088888820000a000088008800000000047a0447a047a0000000000000000000000000000000000000000000000000000000000000000000000000000
+00700700008888200000800008800880a000000a47a4477a047a4440000000000000000000000000000000000000000000000000000000000000000000000000
+000000000008820000a0000008800880080aa080477777a00477777a000000000000000000000000000000000000000000000000000000000000000000000000
+0000000000002000008000000880088000088000477770000422aaaa222200020000020000000000000000000000000000000000000000000000000000000000
+0d5000000000000000000000000000000000000047a77700022ee0002eeee002e00022e000000000000000000000000000000000000000000000000000000000
+d00000000000000000000000000000000000000047a4777002ea2e002e002e02ee022ee000000000000000000000000000000000000000000000000000000000
+500000000000000000000000000000000000000047a0477a22ea2e002e002e02e2e2e2e000000000000000000000000000000000000000000000000000000000
+000000000000000000000000000000000000000047a0047a2e2222e02e222e02e02e02e000000000000000000000000000000000000000000000000000000000
+000000000000000000000000000000000000000047a0047a2eeeeeea2eeee002e02e02e000000000000000000000000000000000000000000000000000000000
+00000000000000000000000000000000000000000aa000aa2e7aa2ea2e00e002e02e02e000000000000000000000000000000000000000000000000000000000
+0000000000000000000000000000000000000000000000002e0002e02e002e02e02e02e000000000000000000000000000000000000000000000000000000000
+0000000000000000000000000000000000000000000000000e0000e00e000e00e00e00e000000000000000000000000000000000000000000000000000000000

vacuum_gambit.p8

@@ -124,11 +124,12 @@ function linked_list:pop_front()
 end
 
 function _init()
+ mode = game_mode
  init_blip_pals()
 	wipe_level()
 	primary_ship.main_gun = zap_gun_p.new()  -- redundant?
 	load_level(example_level_csv)
-	state = game
+	game_state = game
 	pal(2,129)
 	pal()
 end
@@ -157,6 +158,7 @@ function init_hpcols()
 end
 
 function wipe_level()
+ xpwhoosh = nil
  primary_ship = player.new()
  init_hpcols()
  pships = linked_list.new()
@@ -171,7 +173,7 @@ function wipe_level()
 end
 
 function _update60()
- updategame()
+ mode:update()
 end
 
 function call_f(x)
@@ -248,20 +250,40 @@ function updategame()
  intangibles_fg:strip(call_move)
 
 	if leveldone and not eships.next and not ebullets.next and not events.next then
-	  state = win
+	  game_state = win
 	end
-	if (not pships.next) state = lose
+	if (not pships.next) game_state = lose
+
+ if primary_ship.xp >= primary_ship.xptarget then
+  if not xpwhoosh then
+   xpwhoosh = 0
+  else
+   xpwhoosh += 1
+   if (xpwhoosh > 60) xpwhoosh = 0
+  end
+ else
+  xpwhoosh = nil
+ end
 end
 
 function _draw()
+ mode:draw()
+end
+
+function drawgame_top()
  fillp(0)
  drawgame()
- if (state == game) fadelvl = -45
- if (state == win) dropshadow("win",50,61,11)
- if (state == lose) dropshadow("fail",48,61,8)
+ if (game_state == game) fadelvl = -45
+ if (game_state == win) dropshadow("win",50,61,11)
+ if (game_state == lose) dropshadow("fail",48,61,8)
  fadescreen()
 end
 
+game_mode = {
+ update = updategame,
+ draw = drawgame_top,
+}
+
 fadetable = split"0,1.5,1025.5,1029.5,1285.5,1413.5,9605.5,9637.5,-23130.5,-23066.5,-18970.5,-18954.5,-2570.5,-2568.5,-520.5,-8.5,-0.5"
 
 function fadescreen()
@@ -340,14 +362,24 @@ function drawhud()
  draw_gun_info("🅾️",1,116,29,primary_ship.special_gun)
  
  inset(114,57,119,118)
- rectfill(119,57,125,58,13)
+ rectfill(119,57,124,58,13)
  inset(120,64,125,125)
- rectfill(114,124,120,125,13)
- print("XP",120,56,1)
- print("HP",113,121,1)
+ rectfill(114,124,120,125,7)
+ print("XP",119,55,1)
+ print("HP",114,122,1)
  fillp(0x5a5a)
- vertmeter(115,58,118,117,primary_ship.xp, primary_ship.xptarget, powcols)
- -- 59 px vertically
+ if xpwhoosh then
+  clip(115,58,4,60)
+  rectfill(115,58,118,117,0xaa)
+  local voff = 5*xpwhoosh+6
+  rectfill(115,118-voff,118,117-voff+10,0xbb)
+  rectfill(115,118-voff+11,118,117-voff+20,0xba)
+  clip()
+ else
+  vertmeter(115,58,118,117,primary_ship.xp, primary_ship.xptarget, powcols)
+ end
+ -- 59 px vertically? or 60? off-by-1 error somewhere here or in vertmeter?
+ -- it's here. I think
  local mxs, cs, mxh, ch = primary_ship.maxshield, primary_ship.shield, primary_ship.maxhp, primary_ship.hp
  if (mxs > 0) and (mxh > 0) then
   local split = 59 * (mxs / (mxs + mxh)) \ 1 + 64
@@ -389,6 +421,7 @@ end
 
 function vertmeter(x0,y0,x1,y1,val,maxval,cols)
  if ((val <= 0) or (maxval <= 0)) return
+ val=min(val, maxval)
  local h = y1-y0
  local px = val/maxval * h \ 1
  local ncols = #cols
@@ -409,7 +442,7 @@ function inset(x0,y0,x1,y1)
  -- fillp
  rect(x0,y0,x1,y1,119)
  line(x1,y0,x0,y0,85)
- line(x0,y1,85)
+ line(x0,y1-1,85)
 end
 
 function dropshadow(str, x, y, col)
@@ -429,6 +462,7 @@ ship_m = mknew{
  maxshield = 0,
  shieldcooldown =  0x0.003c,--1s
  shieldpenalty = 0x0.012c, --5s
+ shield_refresh_ready = 0,
  
  slip = true,  -- most enemies slide
  
@@ -445,7 +479,26 @@ ship_m = mknew{
 
 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) return
+
+ -- blow up and drop xp
+ local sz4 = self.size * 4
+ local cx, cy, xp, z = self.x + sz4, self.y + sz4, self.xp or 0, 0
+ boom(cx, cy, 3*sz4, self.boss)
+ if xp > 499 then
+  -- spawn a huge gem with all
+  -- overage XP, min 100
+  spawn_xp_at(cx, cy, 0, xp-399)
+  xp = 399
+  z += 1
+ end
+ for gsz in all{100, 25, 5, 1} do
+  while xp >= gsz do
+   spawn_xp_at(cx, cy, z, gsz)
+   xp -= gsz
+   z += 1
+  end
+ end
 end
 
 function ship_m:calc_velocity(v0, t)
@@ -628,7 +681,7 @@ function bullet_base:move()
  self.x += self.dx
  self.y += self.dy
  if (self.f) self.f -= 1
- if (self.y > 128) or (self.y < -8 * self.height) or (self.f and self.f < 0) then
+ if (self.y > 145) or (self.y < -8 * self.height) or (self.f and self.f < 0) then
   self:die()
   return true
  end
@@ -897,9 +950,9 @@ player = mknew(ship_m.new{
  shield = 2, -- regenerates
  maxshield = 2,
 
- -- xp, increments of 0x0.01
+ -- xp; watch out for 16-bit range limits
  xp = 0,
- xptarget = 0x0.05,
+ xptarget = 4,
  level = 1,
 
  -- gun
@@ -956,8 +1009,8 @@ frownie = mknew(ship_m.new{
  sparks = smokespark,
  sparkodds = 8,
  
- -- health
  hp = 0.5, -- enemy ships need no max hp
+ xp = 1,
 
  -- position
  x=60, -- x and y are for upper left corner
@@ -979,6 +1032,7 @@ frownie = mknew(ship_m.new{
 blocky = mknew(frownie.new{
  sprite = 10,
  hp = 1.5,
+ xp = 2,
  hurt = {
   x_off = 0,
   y_off = 0,
@@ -998,6 +1052,7 @@ blocky = mknew(frownie.new{
 
 spewy = mknew(frownie.new{
  sprite=26,
+ xp = 3,
  hurt = {
   x_off=0,
   y_off=1,
@@ -1018,6 +1073,7 @@ spewy = mknew(frownie.new{
 
 chasey = mknew(ship_m.new{
  sprite = 5,
+ xp = 4,
  size = 1,
  hurt = {
   x_off = 1,
@@ -1052,6 +1108,7 @@ end
 
 xl_chasey=mknew(chasey.new{
  size=2,
+ xp = 10,
  maxspd=1.25,
  hurt = {
   x_off = 2,
@@ -1415,362 +1472,6 @@ example_level_csv=[[1,spawn_frownie
 720,spawn_blocking_boss_chasey
 721,eol]]
 
--->8
--- readme.md
-
---[[
-
-main loop sequence
-==================
-1. level_frame
-2. events
-3. merge new_events into events
-4. update bg intangibles
-5. move ships (player first)
-6. move bullets (player first)
-7. calculate collisions
- 1. pship on eship
- 2. ebullet on pship
- 3. pbullet on eship
-8. update fg intangibles
-9. check for end of level
-
-draw order
-----------
-bottom to top:
-1. intangibles_bg
-2. player bullets
-3. player ships
-4. enemy ships
-5. enemy bullets
-6. intangibles_fg
-
-notes
------
-intangibles_fg move()s after
-all collisions and other moves
-are processed. if an intangible
-is added to the list as a result
-of a collision or move, it will
-itself be move()d before it is
-drawn.
-
-data-driven items
-=================
-guns and bullets both allow the
-most common behaviors to be
-expressed with data alone.
-ships only need a movement
-algorithm expressed.
-
-guns
-----
-* t - metatable for bullet type.
-  fired once in the bullet's
-  default direction per shot.
-* enemy - if true, fired bullets
-  are flagged as enemy bullets.
-* icon - sprite index of an
-  8x8 sprite to display in the
-  hud when the player has this
-  gun. default is 20, a generic
-  crosshair bullseye thing.
-* cooldown - min frames between
-  shots.
-* ammo, maxammo - permitted
-  number of shots. 0 is empty
-  and unfireable. maxammo = 0
-  will cause a divide by zero
-  so don't do that. if nil,
-  ammo is infinite.
-
-default guns manage ammo and
-cooldown in shoot, then call
-actually_shoot to create the
-projectile. override only
-actually_shoot to change
-projectile logic while keeping
-cooldown and ammo logic.
-
-bullets
--------
-* dx, dy - movement per frame.
-  player bullets use -dy
-  instead.
-* enemyspd - multiplier for dx
-  and dy on enemy bullets.
-  default is 0.5, making enemy
-  shots much easier to dodge
-* damage - damage per hit;
-  used by ships
-* sprite - sprite index.
-* 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.
-  assume a pixel's coordinates
-  refer to the upper left corner
-  of the pixel; the center of
-  a 2-width bullet with an
-  upper left corner at 0 is 1,
-  not 0.5.
-* top_off_y, bottom_off_y -
-  also for positioning when
-  firing. positive distance from
-  top or bottom edge to image.
-  top_off_y will usually be 0,
-  bottom_off_y will not be when
-  bullets are smaller than
-  the sprite box.
-* width, height - measured in
-  full sprites (8x8 boxes), not
-  pixels. used for drawing.
-
-bullets despawn when above or
-below the screen (player or
-enemy bullets, respectively).
-
-by default, bullets despawn
-when they hit something.
-override hitship to change this.
-
-ships
-____
-
-ships move by calculating
-momentum, then offsetting their
-position by that momentum, then
-clamping their position to the
-screen (horizontally only for
-ships that autoscroll). ships
-that autoscroll (slip==true)
-then slide down by scrollspeed.
-fractional coordinates are ok.
-after movement, ships lose
-momentum (ship.drag along each
-axis). abs(momentum) can't
-exceed ship.maxspeed.
-
-ships gain momentum by acting
-like a player pushing buttons.
-the player ship actually reads
-buttons for this.
-
-act -- returns new acceleration:
-dx, dy, shoot_spec, shoot_main.
-dx and dy are change in momentum
-in px/frame. this is controls
-only -- friction is handled in
-ship:move (`drag` value).
-
-ships hitting another ship take
-1 damage per frame of overlap.
-ships hitting a bullet check
-bullet.damage to find out how
-much damage they take. damage
-is applied to shields, then hp.
-damaged ships flash briefly -
-blue (12) if all damage was
-shielded, white (7) if hp was
-damaged. a ship that then has 0
-or less hp calls self:die() and
-tells the main game loop to
-remove it.
-
-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
-are treated as 0, but a bullet
-can choose to repair the ship
-it hits in its own hitship
-method, or otherwise edit it
-(changing weapons, refilling
-weapon ammo). powerups are
-therefore a kind of bullet.
-
-levels
-======
-
-a level is a table mapping
-effective frame number to
-functions. when a level starts,
-it sets lframe ("level frame")
-and distance to 0.
-
-every frame, level_frame
-increments lframe by 0x0.0001.
-then if the level is not frozen,
-it increments distance by 1.0
-and runs the function in the
-level table for exactly that
-frame number (if any). distance
-is therefore "nonfrozen frames",
-and is used to trigger level
-progress. lframe always
-increments. ships are encouraged
-to use lframe to control
-animation and movement, and may
-use distance to react to level
-progress separately from overall
-time. remember to multiply
-lframe-related stuff by 0x0001.
-
-a special sentinel value, eol,
-marks the end of the level.
-(the level engine doesn't know
-when it's out of events, so
-without eol, the level will
-simply have no events forever.)
-when it finds eol, level_frame
-throws away the current level
-and tells the main loop that it
-might be done. the main loop
-agrees the level is over and the
-player has won when the level
-has reached eol and there are
-no more enemy ships, enemy
-bullets, or background events
-remaining. player ships, player
-bullets, and intangibles are
-not counted.
-
-level freezing
---------------
-the level is frozen when the
-global value freeze > 0.
-generally, something intending
-to block level progress (a
-miniboss, a minigame, etc.)
-increments freeze and prepares
-some means of decrementing it
-when it no longer wants to block
-level progress.
-
-most commonly, we want to block
-until some specific ship or
-group of ships has died. for
-these ships, override ship:die
-to decrement freeze. make sure
-to set ship.dead in any new
-ship:die method so anything else
-looking at it can recognize
-the ship as dead.
-
-for anything else, you probably
-want an event to figure out when
-to unfreeze.
-
-levels start at 1
------------------
-
-distance is initialized to 0
-but gets incremented before the
-first time the engine looks for
-events. therefore, the first
-frame of the level executes
-level[1]. since levelframe
-executes before anything else,
-level[1] sets up the first frame
-drawn in the level. the player
-does not see a blank world
-before level[1] runs.
-level[1] can therefore be used
-to reconfigure the player ship,
-set up backgrounds, start music,
-kick off some kind of fade-in
-animation, etc.
-
-
-events
-======
-the global list "events" stores
-0-argument functions which are
-called every frame. if they
-return true, they are removed
-from the list and not run again;
-if they return false, they stay
-and will be called in later
-frames. the level does not end
-while the events table is
-nonempty.
-
-events are most commonly used
-to set up something for later
-(for example, blip uses an event
-to remove the fx_pallete from
-the flashing ship when the blip
-expires), but can also be used
-to implement a "level within a
-level" that does something
-complicated until it's done. if
-you froze the level when
-creating the event, remember
-to thaw it (freeze -= 1) on all
-paths that return true.
-
-to do complex stuff in events,
-use a closure or a metatable
-that specifies __call.
-
-to avoid editing the events
-list while it is being iterated,
-events that create new events
-must add those events to
-new_events rather than events.
-new_events is only valid during
-the "event execution" stage, so
-events created at any other time
-must go directly on events
-without using new_events.
-
-intangibles
-===========
-
-the intangibles_fg and
-intangibles_bg lists contain
-items with :move and :draw.
-like ships and bullets, they
-move during _update60 and
-draw during _draw. they are
-not checked for collisions.
-
-intangibles_bg moves/draws
-before anything else moves or
-draws. intangibles_fg
-moves/draws last. this controls
-whether your intangible object
-draws in front of or behind
-other stuff. you probably want
-intangibles_bg for decorative
-elements and intangibles_fg
-for explosions, score popups,
-etc.
-
-there's no scrolling background
-engine but intangibles_bg could
-be used to create one, including
-using the map (otherwise unused
-in this engine) for the purpose.
-
-intangibles do not prevent the
-level from ending. like bullets
-and ships, if :move returns
-true, they are dropped.
-]]
 -->8
 -- standard events
 
@@ -1855,6 +1556,61 @@ end
 -->8
 -- powerups
 
+xp_gem = mknew(bullet_base.new{
+ dx = 0,
+ dy = 0.75,
+ width=1, -- not used for spr but
+ height=1,-- bullet_base uses it
+ category = enemy_blt_cat,
+ damage = 0,
+ hurt = {
+  x_off = -2,
+  y_off = -2,
+  width = 8,
+  height = 8,
+ },
+ x_off = 2,
+ y_off = 2,
+})
+
+function xp_gem:draw()
+ local s,qx,qy = self.qsprite,0,0
+ -- sprite map position:
+ -- sprite id to x and y,
+ -- offset shifts specific low
+ -- bits of lframe up to the the
+ -- bit with value 4 as a cheap
+ -- way to pick an anim frame
+ if (lframe&0x0.003 == 0) qx, qy = (lframe&0x0.0004)<<16, (lframe&0x0.0008)<<15
+ sspr(
+  (s%16<<3)+qx,
+  (s\16<<3)+qy,
+  4, 4,
+  self.x, self.y
+ )
+end
+
+-- todo: "magnetic" behavior
+-- when near player ship
+
+function xp_gem:hitship(ship)
+ if (ship ~= primary_ship) return false
+ primary_ship.xp += self.val
+ primary_ship.last_xp_frame = lframe
+ return true
+end
+
+-- small gems for 1, 5, 25
+-- exactly; else huge
+function spawn_xp_at(x, y, off, amt)
+ x += rnd(off+off)-off
+ y += rnd(off+off)-off
+ xp_gem.new{
+  qsprite=amt == 1 and 32 or amt == 5 and 33 or amt == 25 and 34 or 35,
+  val = amt,
+ }:spawn_at(mid(x, 0, 124),mid(y,-4,125))
+end
+
 powerup = mknew(bullet_base.new{
  -- animated sprite array: "sprites"
  -- to draw under or over anim,
@@ -1870,7 +1626,7 @@ powerup = mknew(bullet_base.new{
  -- but powerups should feel
  -- easy to pick up
  dx = 0,
- dy = 1.5, -- 0.75 after enemyspd
+ dy = 0.75,
  category = enemy_blt_cat, -- collides with player ship
  damage = 0,
  
@@ -1881,11 +1637,6 @@ powerup = mknew(bullet_base.new{
 -- sprite indexes for "sheen" animation
 sheen8x8 = split"2,54,55,56,57,58,59,60,61"
 
--- todo: draw two sprites
--- on top of each other here
--- so all powerups can share
--- the "sheen" animation?
-
 function powerup:draw()
  spr(self.sprites[max(1,
        ((lframe<<16)\self.anim_speed)
@@ -1992,6 +1743,7 @@ function spawn_spec_gun_at(x, y, gunt)
  }
  gun_p:spawn_at(x, y)
 end
+
 __gfx__
 00000000000650000000000000000000bb0b50b59909209200cc0c00000000003b00000082000000e00e8002e00e800200333300002222000000000000000000
 00000000006765000000000000cccc00b50b3055920940220c0000c000bbbb0037000000a2000000e0e8880240e8480403bbbb30028888200000000000000000
@@ -2009,14 +1761,14 @@ __gfx__
 000000005666657576667650000000000b0000b000000000000000000000000000000000000dd0009092220200000000c111111d656667650000000000000000
 0000000056565066665656500000000000bbbb0000000000000000000000000000000000000000000090020000000000c111111d650650650000000000000000
 00000000565000566500065000000000b000000b000000000000000000000000000000000000000000a00a0000000000cddddddd650000650000000000000000
-000000000000000000000000000000000000000000a0008000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000000000000000000000000000000000000090008000000000000000000000000000000000000000000000000000000000000000000000000000000000
-000000000000000000000000000000000000000000800a0000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000000000000000000000000000000000000080090000000000000000000000000000000000000000000000000000000000000000000000000000000000
-0000000000000000000000000000000000000000000a080000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000000000000000000000000000000000000009080000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+000000000c00070006000700066007600000000000a0008000000000000000000000000000000000000000000000000000000000000000000000000000000000
+0c000700ccd07cd06cd07cd06ccd7ccd000000000090008000000000000000000000000000000000000000000000000000000000000000000000000000000000
+0d000d000d000d006cd06cd06ccd6ccd0000000000800a0000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00000000000000000d000d000dd00dd0000000000080090000000000000000000000000000000000000000000000000000000000000000000000000000000000
+000000000c000c00060006000670066000000000000a080000000000000000000000000000000000000000000000000000000000000000000000000000000000
+0c000c00c7d0cc7067d06cd067cd6ccd000000000009080000000000000000000000000000000000000000000000000000000000000000000000000000000000
+07000c000d0007007cd06c707ccd6c77000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00000000000000000d0007000dd00d70000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000cccccccccccccccc77000000007700000000770000000077000000000000000000000000000000000000000000000000
 00000000000000000000000000000000c116611dc11ee11d70000000077000000007700000000770000000070000000000000000000000000000000000000000
 00000000000000000000000000000000c1611c1dc11ee11d00000000770000000077000000007700000000770000000700000000000000000000000000000000