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"""
A simple particle engine implementation.
"""
from .compat import *
from .ebs import System
__all__ = ["Particle", "ParticleEngine"]
class Particle(object):
"""A simple particle component type.
The Particle component only contains information about a x- and
y-coordinate and its current life time. The life time will be
decreased by 1, everytime the particle is processed by the
ParticleEngine.
"""
def __init__(self, x, y, life):
"""Creates a new Particle with a x-/y-position and life time."""
super(Particle, self).__init__()
self.x = x
self.y = y
self.life = life
@property
def position(self):
"""The position of the Particle as tuple."""
return self.x, self.y
@position.setter
def position(self, value):
"""The position of the Particle as tuple."""
self.x = value[0]
self.y = value[1]
class ParticleEngine(System):
"""A simple particle processing system.
The ParticleEngine takes care of creating, updating and deleting
particles via callback functions. It only decreases the life of the
particles by itself and marks them as dead, once the particle's life
attribute has reached 0 or below.
"""
def __init__(self):
"""Creates a new ParticleEngine."""
super(ParticleEngine, self).__init__()
self.componenttypes = (Particle,)
self._createfunc = None
self._deletefunc = None
self._updatefunc = None
def process(self, world, components):
"""Processes all particle components, decreasing their life by 1.
Once the life of all particle components has been decreased
properly and the particles considered dead (life <= 0) are
identified, the creation, update and deletion callbacks are
invoked.
The creation callback takes the passed world as first and the
list of dead particles as second argument.
def particle_createfunc(world, list_of_dead_ones):
...
Afterwards the still living particles are passed to the update
callback, which also take the passed world as first and the
living particles as set as second argument.
def particle_updatefunc(world, set_of_living_ones):
...
Finally, the dead particles need to be deleted in some way or
another, which is done by the deletion callback, taking the
passed world as first and the list of dead particles as second
argument.
def particle_deletefunc(world, list_of_dead_ones):
...
"""
deadones = []
dappend = deadones.append
for p in components:
p.life -= 1
if p.life <= 0:
dappend(p)
self.createfunc(world, deadones)
self.updatefunc(world, set(components) - set(deadones))
self.deletefunc(world, deadones)
@property
def createfunc(self):
"""The function to be used for creating new particles."""
return self._createfunc
@createfunc.setter
def createfunc(self, value):
"""The function to be used for creating new particles."""
if not callable(value):
raise TypeError("createfunc must be callable")
self._createfunc = value
@property
def deletefunc(self):
"""The function to be used for deleting dead particles."""
return self._deletefunc
@deletefunc.setter
def deletefunc(self, value):
"""The function to be used for deletíng dead particles."""
if not callable(value):
raise TypeError("deletefunc must be callable")
self._deletefunc = value
@property
def updatefunc(self):
"""The function to be used for updating particles."""
return self._updatefunc
@updatefunc.setter
def updatefunc(self, value):
"""The function to be used for updating particles."""
if not callable(value):
raise TypeError("updatefunc must be callable")
self._updatefunc = value
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