bulletml/impl.py

   1 """BulletML implementation."""
   2
   3 from __future__ import division
   4
   5 import math
   6
   7 from bulletml import parser
   8
   9 PI_2 = math.pi * 2
  10
  11 __all__ = ["Action", "Bullet"]
  12
  13 class Action(object):
  14     """Running action implementation.
  15
  16     To implement new actions,
  17
  18     - Add a new element/class pair to parser.ActionDef.CONSTRUCTORS.
  19       It should support FromXML, __getstate__, and __setstate__.
  20     - Subclass impl.Action and override the 'handle' method to handle
  21       your custom action type.
  22     - Pass the impl.Bullet constructor your Action subclass when
  23       creating your root Bullet.
  24     """
  25
  26     def __init__(self, owner, parent, actions, params, rank, repeat=1):
  27         self.actions = actions
  28         self.parent = parent
  29         self.repeat = repeat
  30         self.wait_frames = 0
  31         self.speed = 0
  32         self.speed_frames = 0
  33         self.direction = 0
  34         self.direction_frames = 0
  35         self.aiming = False
  36         self.mx = 0
  37         self.my = 0
  38         self.accel_frames = 0
  39         self.previous_fire_direction = 0
  40         self.previous_fire_speed = 0
  41         self.params = params
  42         self.pc = -1
  43         self.finished = False
  44         if parent:
  45             self.copy_state(parent)
  46
  47     def __repr__(self):
  48         return "%s(pc=%r, actions=%r)" % (
  49             type(self).__name__, self.pc, self.actions)
  50
  51     def vanish(self):
  52         """End this action and its parents."""
  53         if self.parent:
  54             self.parent.vanish()
  55         self.pc = None
  56         self.finished = True
  57
  58     def copy_state(self, other):
  59         """Copy fire/movement state from other to self."""
  60         self.direction_frames = other.direction_frames
  61         self.direction = other.direction
  62         self.aiming = other.aiming
  63         self.speed_frames = other.speed_frames
  64         self.speed = other.speed
  65         self.accel_frames = other.accel_frames
  66         self.mx = other.mx
  67         self.my = other.my
  68         self.previous_fire_direction = other.previous_fire_direction
  69         self.previous_fire_speed = other.previous_fire_speed
  70
  71     def step(self, owner, created, sin=math.sin, cos=math.cos):
  72         """Advance by one frame."""
  73         s_params = self.params
  74         rank = owner.rank
  75
  76         if self.speed_frames > 0:
  77             self.speed_frames -= 1
  78             owner.speed += self.speed
  79
  80         if self.direction_frames > 0:
  81             # The Noiz implementation was a little weird here, I think
  82             # there was a bug in it that prevented it from working if
  83             # the frame count was 1. I'm still not sure what the aim
  84             # check is supposed to do, exactly.
  85             self.direction_frames -= 1
  86             if self.aiming and self.direction_frames <= 0:
  87                 owner.direction += owner.aim
  88             else:
  89                 owner.direction += self.direction
  90
  91         if self.accel_frames > 0:
  92             self.accel_frames -= 1
  93             owner.mx += self.mx
  94             owner.my += self.my
  95
  96         if self.pc is None:
  97             return
  98
  99         if self.wait_frames > 0:
 100             self.wait_frames -= 1
 101             return
 102
 103         while True:
 104             self.pc += 1
 105
 106             try:
 107                 action = self.actions[self.pc]
 108             except IndexError:
 109                 self.repeat -= 1
 110                 if self.repeat <= 0:
 111                     self.pc = None
 112                     self.finished = True
 113                     if self.parent is not None:
 114                         self.parent.copy_state(self)
 115                         owner.replace(self, self.parent)
 116                     break
 117                 else:
 118                     self.pc = 0
 119                     action = self.actions[self.pc]
 120
 121             if isinstance(action, parser.Repeat):
 122                 repeat, (actions, params) = action(s_params, rank)
 123                 child = self.__class__(
 124                     owner, self, actions, params, rank, repeat)
 125                 owner.replace(self, child)
 126                 child.step(owner, created, sin, cos)
 127                 break
 128
 129             elif isinstance(action, (parser.ActionDef, parser.ActionRef)):
 130                 actions, params = action(s_params, rank)
 131                 child = self.__class__(owner, self, actions, params, rank)
 132                 owner.replace(self, child)
 133                 child.step(owner, created, sin, cos)
 134                 break
 135
 136             elif isinstance(action, (parser.FireDef, parser.FireRef)):
 137                 direction, speed, actions, offset = action(s_params, rank)
 138                 if direction:
 139                     direction, type = direction
 140                     if type == "aim" or type is None:
 141                         direction += owner.aim
 142                     elif type == "sequence":
 143                         direction += self.previous_fire_direction
 144                     elif type == "relative":
 145                         direction += owner.direction
 146                 else:
 147                     direction = owner.aim
 148                 self.previous_fire_direction = direction
 149
 150                 if speed:
 151                     speed, type = speed
 152                     if type == "sequence":
 153                         speed += self.previous_fire_speed
 154                     elif type == "relative":
 155                         # The reference Noiz implementation uses
 156                         # prvFireSpeed here, but the standard is
 157                         # pretty clear -- "In case of the type is
 158                         # "relative", ... the speed is relative to the
 159                         # speed of this bullet."
 160                         speed += owner.speed
 161                 else:
 162                     speed = 1
 163                 self.previous_fire_speed = speed
 164
 165                 x, y = owner.x, owner.y
 166                 if offset:
 167                     off_x, off_y = offset(s_params, rank)
 168                     if offset.type == "relative":
 169                         s = sin(direction)
 170                         c = cos(direction)
 171                         x += c * off_x + s * off_y
 172                         y += s * off_x - c * off_y
 173                     else:
 174                         x += off_x
 175                         y += off_y
 176
 177                 bullet = owner.__class__(
 178                     x, y, direction, speed, owner.target, actions, rank)
 179                 created.append(bullet)
 180
 181             elif isinstance(action, parser.ChangeSpeed):
 182                 frames, (speed, type) = action(s_params, rank)
 183                 self.speed_frames = frames
 184                 if frames <= 0:
 185                     if type == "absolute":
 186                         owner.speed = speed
 187                     elif type == "relative":
 188                         owner.speed += speed
 189                 elif type == "sequence":
 190                     self.speed = speed
 191                 elif type == "relative":
 192                     self.speed = speed / frames
 193                 else:
 194                     self.speed = (speed - owner.speed) / frames
 195
 196             elif isinstance(action, parser.ChangeDirection):
 197                 frames, (direction, type) = action(s_params, rank)
 198                 self.direction_frames = frames
 199                 self.aiming = False
 200                 if type == "sequence":
 201                     self.direction = direction
 202                 else:
 203                     if type == "absolute":
 204                         direction -= owner.direction
 205                     elif type != "relative": # aim or default
 206                         self.aiming = True
 207                         direction += owner.aim - owner.direction
 208
 209                     # Normalize to [-pi, pi).
 210                     direction = (direction + math.pi) % PI_2 - math.pi
 211                     if frames <= 0:
 212                         owner.direction += direction
 213                     else:
 214                         self.direction = direction / frames
 215
 216             elif isinstance(action, parser.Accel):
 217                 frames, horizontal, vertical = action(s_params, rank)
 218                 self.accel_frames = frames
 219                 if horizontal:
 220                     mx, type = horizontal
 221                     if frames <= 0:
 222                         if type == "absolute":
 223                             owner.mx = mx
 224                         elif type == "relative":
 225                             owner.mx += mx
 226                     elif type == "sequence":
 227                         self.mx = mx
 228                     elif type == "absolute":
 229                         self.mx = (mx - owner.mx) / frames
 230                     elif type == "relative":
 231                         self.mx = mx / frames
 232                 if vertical:
 233                     my, type = vertical
 234                     if frames <= 0:
 235                         if type == "absolute":
 236                             owner.my = my
 237                         elif type == "relative":
 238                             owner.my += my
 239                     elif type == "sequence":
 240                         self.my = my
 241                     elif type == "absolute":
 242                         self.my = (my - owner.my) / frames
 243                     elif type == "relative":
 244                         self.my = my / frames
 245
 246             elif isinstance(action, parser.Tag):
 247                 owner.tags.add(action.tag)
 248
 249             elif isinstance(action, parser.Untag):
 250                 try:
 251                     owner.tags.remove(action.tag)
 252                 except KeyError:
 253                     pass
 254
 255             elif isinstance(action, parser.Wait):
 256                 self.wait_frames = action(s_params, rank)
 257                 break
 258
 259             elif isinstance(action, parser.Vanish):
 260                 owner.vanish()
 261                 break
 262
 263             else:
 264                 self.handle(action, owner, created, sin, cos)
 265
 266     def handle(self, action, owner, created, sin, cos):
 267         """Override in subclasses for new action types."""
 268         raise NotImplementedError(action.__class__.__name__)
 269
 270 class Bullet(object):
 271     """Simple bullet implementation.
 272
 273     Attributes:
 274     x, y - current X/Y position
 275     px, py - X/Y position prior to the last step
 276     mx, my - X/Y axis-oriented speed modifier ("acceleration")
 277     direction - direction of movement, in radians
 278     speed - speed of movement, in units per frame
 279     target - object with .x and .y fields for "aim" directions
 280     vanished - set to true by a <vanish> action
 281     rank - game difficulty, 0 to 1, default 0.5
 282     tags - string tags set by the running actions
 283
 284     Contructor Arguments:
 285     x, y, direction, speed, target, rank - same as the attributes
 286     actions - internal action list
 287     parent - parent of actions, None for manually-created bullets
 288
 289
 290     """
 291
 292     def __init__(self, x=0, y=0, direction=0, speed=0, target=None,
 293                  actions=(), rank=0.5, Action=Action):
 294         self.x = self.px = x
 295         self.y = self.py = y
 296         self.mx = 0
 297         self.my = 0
 298         self.direction = direction
 299         self.speed = speed
 300         self.vanished = False
 301         self.target = target
 302         self.rank = rank
 303         self.tags = set()
 304         # New bullets reset the parent hierarchy.
 305         self._actions = [Action(self, None, action, params, rank)
 306                          for action, params in actions]
 307
 308     def __repr__(self):
 309         return ("%s(%r, %r, accel=%r, direction=%r, speed=%r, "
 310                 "actions=%r, target=%r, vanished=%r)") % (
 311             type(self).__name__, self.x, self.y, (self.mx, self.my),
 312             self.direction, self.speed, self._actions, self.target,
 313             self.vanished)
 314
 315     @property
 316     def aim(self):
 317         """Angle to the target, in radians."""
 318         if self.target is None:
 319             return self.direction
 320         else:
 321             return math.atan2(self.target.x - self.x, self.y - self.target.y)
 322
 323     @property
 324     def finished(self):
 325         """Check if this bullet is finished running.
 326
 327         A bullet is finished when it has vanished, and all its
 328         actions have finished.
 329
 330         If this is true, the bullet should be removed from the screen.
 331         (You will probably want to cull it under other circumstances
 332         as well).
 333         """
 334         if not self.vanished:
 335             return False
 336         for action in self._actions:
 337             if not action.finished:
 338                 return False
 339         return True
 340
 341     def vanish(self):
 342         """Vanish this bullet and stop all actions."""
 343         self.vanished = True
 344         for action in self._actions:
 345             action.vanish()
 346         self._actions = []
 347
 348     def replace(self, old, new):
 349         """Replace an active action with another.
 350
 351         This is mostly used by actions internally to queue children.
 352         """
 353         try:
 354             idx = self._actions.index(old)
 355         except ValueError:
 356             pass
 357         else:
 358             self._actions[idx] = new
 359
 360     def step(self, sin=math.sin, cos=math.cos):
 361         """Advance by one frame.
 362
 363         This updates the position and velocity, and may also set the
 364         vanished flag.
 365
 366         It returns any new bullets this bullet spawned during this step.
 367         """
 368         created = []
 369
 370         for action in self._actions:
 371             action.step(self, created, sin, cos)
 372
 373         self.px = self.x
 374         self.py = self.y
 375         self.x += self.mx + sin(self.direction) * self.speed
 376         self.y += self.my - cos(self.direction) * self.speed
 377
 378         return created