1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
.. module:: sdl2.ext.particles
:synopsis: A simple particle system.
A simple particle system
========================
.. class:: ParticleEngine()
A simple particle processing system. The :class:`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.
.. attribute:: createfunc
Function for creating new particles. The function needs to take
two arguments, the ``world`` argument passed to :meth:`process()`
and a list of the particles considered dead (:attr:`Particle.life`
<= 0). ::
def creation_func(world, deadparticles):
...
.. attribute:: updatefunc
Function for updating existing, living particles. The function
needs to take two arguments, the ``world`` argument passed to
:meth:`process()` and a :class:`set` of the still living
particles. ::
def update_func(world, livingparticles):
...
.. attribute:: deletefunc
Function for deleting dead particles. The function needs to take
two arguments, the ``world`` argument passed to :meth:`process()`
and a list of the particles considered dead (:attr:`Particle.life`
<= 0). ::
def deletion_func(world, deadparticles):
...
.. method:: process(world : World, components : iterable) -> None
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):
...
.. class:: Particle(x, y, life : int)
A simple particle component type. It only contains information about
a x- and y-coordinate and its current life time. The life time will
be decreased by 1, every time the particle is processed by the
:class:`ParticleEngine`.
.. attribute:: x
The x coordinate of the particle.
.. attribute:: y
The y coordinate of the particle.
.. attribute:: life
The remaining life time of the particle.
.. attribute:: position
The x- and y-coordinate of the particle as tuple.
|
