dgt.particle source code

1 module dgt.particle;
2 import dgt.geom, dgt.texture, dgt.util;
3 
4 /**
5 Controls the behavior of particles when they collide with a tilemap
6 
7 Ignore means the particles will continue as normal, Die will mean the particle disappears, and Bounce will mean the particle rebounds from the wall
8 */
9 enum ParticleBehavior
10 {
11     Ignore, Die, Bounce
12 }
13 
14 /**
15 An individual instance of a particle
16 
17 If you want to spawn particles use Window.addParticleBurst
18 */
19 struct Particle
20 {
21     Texture region;
22     Vector position, velocity, acceleration, scale, scale_velocity;
23     float rotation = 0, rotational_velocity = 0;
24     int lifetime = 0;
25     ParticleBehavior behavior = ParticleBehavior.Ignore;
26 
27     ///Step a particle forward a frame
28     @safe @nogc nothrow pure public void update()
29     {
30         velocity = velocity + acceleration;
31         position = position + velocity;
32         scale = scale + scale_velocity;
33         rotation += rotational_velocity;
34         lifetime--;
35     }
36 }
37 
38 /**
39 A structure that allows particle spawn settings to be tweaked
40 */
41 struct ParticleEmitter
42 {
43     const(Texture[]) regions;
44     Vector top_left, bottom_right, velocity_min, velocity_max,
45         acceleration_min, acceleration_max, scale_min, scale_max,
46         scale_velocity_min, scale_velocity_max;
47     float rotation_min = 0, rotation_max = 0, rotational_velocity_min = 0,
48         rotational_velocity_max = 0;
49     int lifetime_min, lifetime_max;
50     int particle_min, particle_max;
51     ParticleBehavior behavior = ParticleBehavior.Ignore;
52 
53     @disable this();
54 
55     @nogc nothrow public:
56     /**
57     A list of all possible texture regions that the particles can source from
58     */
59     this(in Texture[] regions)
60     {
61         this.regions = regions;
62     }
63 
64     ///Create a single particle
65     Particle emit() const
66     {
67         return Particle(regions[randomRange(0, cast(int)regions.length)],
68              randomRange(top_left, bottom_right),
69              randomRange(velocity_min, velocity_max),
70              randomRange(acceleration_min, acceleration_max),
71              randomRange(scale_min, scale_max),
72              randomRange(scale_velocity_min, scale_velocity_max),
73              randomRange(rotation_min, rotation_max),
74              randomRange(rotational_velocity_min, rotational_velocity_max),
75              randomRange(lifetime_min, lifetime_max),
76              behavior);
77     }
78 }