bastd.gameutils

  1# Released under the MIT License. See LICENSE for details.
  2#
  3"""Various utilities useful for gameplay."""
  4
  5from __future__ import annotations
  6
  7from typing import TYPE_CHECKING
  8
  9import ba
 10
 11if TYPE_CHECKING:
 12    pass
 13
 14
 15class SharedObjects:
 16    """Various common components for use in games.
 17
 18    Category: Gameplay Classes
 19
 20    Objects contained here are created on-demand as accessed and shared
 21    by everything in the current activity. This includes things such as
 22    standard materials.
 23    """
 24
 25    _STORENAME = ba.storagename()
 26
 27    def __init__(self) -> None:
 28        activity = ba.getactivity()
 29        if self._STORENAME in activity.customdata:
 30            raise RuntimeError(
 31                'Use SharedObjects.get() to fetch the'
 32                ' shared instance for this activity.'
 33            )
 34        self._object_material: ba.Material | None = None
 35        self._player_material: ba.Material | None = None
 36        self._pickup_material: ba.Material | None = None
 37        self._footing_material: ba.Material | None = None
 38        self._attack_material: ba.Material | None = None
 39        self._death_material: ba.Material | None = None
 40        self._region_material: ba.Material | None = None
 41        self._railing_material: ba.Material | None = None
 42
 43    @classmethod
 44    def get(cls) -> SharedObjects:
 45        """Fetch/create the instance of this class for the current activity."""
 46        activity = ba.getactivity()
 47        shobs = activity.customdata.get(cls._STORENAME)
 48        if shobs is None:
 49            shobs = SharedObjects()
 50            activity.customdata[cls._STORENAME] = shobs
 51        assert isinstance(shobs, SharedObjects)
 52        return shobs
 53
 54    @property
 55    def player_material(self) -> ba.Material:
 56        """a ba.Material to be applied to player parts. Generally,
 57        materials related to the process of scoring when reaching a goal, etc
 58        will look for the presence of this material on things that hit them.
 59        """
 60        if self._player_material is None:
 61            self._player_material = ba.Material()
 62        return self._player_material
 63
 64    @property
 65    def object_material(self) -> ba.Material:
 66        """A ba.Material that should be applied to any small,
 67        normal, physical objects such as bombs, boxes, players, etc. Other
 68        materials often check for the  presence of this material as a
 69        prerequisite for performing certain actions (such as disabling
 70        collisions between initially-overlapping objects)
 71        """
 72        if self._object_material is None:
 73            self._object_material = ba.Material()
 74        return self._object_material
 75
 76    @property
 77    def pickup_material(self) -> ba.Material:
 78        """A ba.Material; collision shapes used for picking things
 79        up will have this material applied. To prevent an object from being
 80        picked up, you can add a material that disables collisions against
 81        things containing this material.
 82        """
 83        if self._pickup_material is None:
 84            self._pickup_material = ba.Material()
 85        return self._pickup_material
 86
 87    @property
 88    def footing_material(self) -> ba.Material:
 89        """Anything that can be 'walked on' should have this
 90        ba.Material applied; generally just terrain and whatnot. A character
 91        will snap upright whenever touching something with this material so it
 92        should not be applied to props, etc.
 93        """
 94        if self._footing_material is None:
 95            self._footing_material = ba.Material()
 96        return self._footing_material
 97
 98    @property
 99    def attack_material(self) -> ba.Material:
100        """A ba.Material applied to explosion shapes, punch
101        shapes, etc.  An object not wanting to receive impulse/etc messages can
102        disable collisions against this material.
103        """
104        if self._attack_material is None:
105            self._attack_material = ba.Material()
106        return self._attack_material
107
108    @property
109    def death_material(self) -> ba.Material:
110        """A ba.Material that sends a ba.DieMessage() to anything
111        that touches it; handy for terrain below a cliff, etc.
112        """
113        if self._death_material is None:
114            mat = self._death_material = ba.Material()
115            mat.add_actions(
116                ('message', 'their_node', 'at_connect', ba.DieMessage())
117            )
118        return self._death_material
119
120    @property
121    def region_material(self) -> ba.Material:
122        """A ba.Material used for non-physical collision shapes
123        (regions); collisions can generally be allowed with this material even
124        when initially overlapping since it is not physical.
125        """
126        if self._region_material is None:
127            self._region_material = ba.Material()
128        return self._region_material
129
130    @property
131    def railing_material(self) -> ba.Material:
132        """A ba.Material with a very low friction/stiffness/etc
133        that can be applied to invisible 'railings' useful for gently keeping
134        characters from falling off of cliffs.
135        """
136        if self._railing_material is None:
137            mat = self._railing_material = ba.Material()
138            mat.add_actions(('modify_part_collision', 'collide', False))
139            mat.add_actions(('modify_part_collision', 'stiffness', 0.003))
140            mat.add_actions(('modify_part_collision', 'damping', 0.00001))
141            mat.add_actions(
142                conditions=('they_have_material', self.player_material),
143                actions=(
144                    ('modify_part_collision', 'collide', True),
145                    ('modify_part_collision', 'friction', 0.0),
146                ),
147            )
148        return self._railing_material