Annotation of /examples/boids/boids.diderot

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1 :	lamonts	2125	/*! \file flock.diderot
2 :			*
3 :			* \author Lamont Samuels
4 :			*
5 :			* This example is an implementation of Chris Reynolds Boids algorithm. It represents an example of using Spatial communication
6 :			*/
7 :			/*
8 :			* COPYRIGHT (c) 2012 The Diderot Project (http://diderot-language.cs.uchicago.edu)
9 :			* All rights reserved.
10 :			*/
11 :			real{} initVelocities = load("data/velocities.nrrd");
12 :			int numBoids = length(initVelocities)/2;
13 :			int numBoids = length(initVelocities)/2;
14 :			int strandSize = 2;
15 :			real query_radius = 50;
16 :			int MAX_SPEED = 2;
17 :			real MAX_FORCE = 0.05;
18 :			int stepsMax = 10000;
19 :			real boundsFactor = 10.0;
20 :			input int width;
21 :			input int height;
22 :			int NORTH = 0;
23 :			int SOUTH = 1;
24 :			int WEST = 2;
25 :			int EAST = 3;
26 :
27 :			strand Boid(int i,real vx, real vy) {
28 :			vec2 pos = [real(width)/2.0,real(height)/2.0];
29 :			vec2 vel = [vx,vy];
30 :			int steps = 0;
31 :			int id = i;
32 :			output vec4 boidInfo = [pos[0],pos[1],vel[0],vel[1]];
33 :			update {
34 :			vec2 cohereVec = [0.0,0.0];
35 :			vec2 alignVec = [0.0,0.0];
36 :			vec2 seperateVec = [0.0,0.0];
37 :			vec4 wrapDimensions = [-boundsFactor,
38 :			height + boundsFactor,
39 :			-boundsFactor,
40 :			width + boundsFactor];
41 :			int count = 0;
42 :
43 :			foreach(Boid neighbor in sphere(query_radius)){
44 :			real d = dist(pos,neighbor.pos);
45 :
46 :			if(d > 0) {
47 :			cohereVec += neighbor.pos;
48 :			alignVec += neighbor.vel;
49 :			seperateVec = seperateVec + (normalize(pos-neighbor.pos)/d);
50 :			count+=1;
51 :			}
52 :			}
53 :
54 :			if(count > 0) {
55 :			cohereVec /= real(count);
56 :			alignVec /= real(count);
57 :			seperateVec /= real(count);
58 :			}
59 :
60 :			real isZero = alignVec • alignVec;
61 :
62 :			// limit the force
63 :			if ( isZero != 0 && |alignVec| > MAX_FORCE) {
64 :			alignVec = normalize(alignVec);
65 :			alignVec *= MAX_FORCE;
66 :			}
67 :
68 :
69 :			vec2 diff = cohereVec - pos;
70 :			isZero = cohereVec • cohereVec;
71 :
72 :			if(|diff| > 0 && isZero != 0){
73 :
74 :			cohereVec = normalize(cohereVec);
75 :
76 :			if(|diff| < 100.0) {
77 :			cohereVec *= (MAX_SPEED*(|diff|/100.0));
78 :			}else {
79 :			cohereVec *= MAX_SPEED;
80 :			}
81 :
82 :			cohereVec -= vel;
83 :
84 :			// limit the force
85 :			if (|cohereVec| > MAX_FORCE) {
86 :			cohereVec = normalize(cohereVec);
87 :			cohereVec *= MAX_FORCE;
88 :			}
89 :			}
90 :			else{
91 :			cohereVec = [0.0,0.0];
92 :			}
93 :
94 :
95 :			vec2 acceleration = cohereVec + alignVec + seperateVec;
96 :			vel += acceleration;
97 :
98 :			if (|vel| > MAX_SPEED){
99 :			vel = normalize(cohereVec);
100 :			vel *= MAX_SPEED;
101 :			}
102 :
103 :			pos += vel;
104 :
105 :			/* Wrapping Code, if a boid goes outside the window */
106 :			real posX = wrapDimensions[EAST] if pos[0] < wrapDimensions[WEST]
107 :			else wrapDimensions[WEST] if pos[0] > wrapDimensions[EAST]
108 :			else pos[0];
109 :
110 :			real posY = wrapDimensions[SOUTH] if pos[1] < wrapDimensions[NORTH]
111 :			else wrapDimensions[NORTH] if pos[1] > wrapDimensions[SOUTH]
112 :			else pos[1];
113 :
114 :			pos = [posX,posY];
115 :
116 :			boidInfo = [pos[0],pos[1], vel[0], vel[1]];
117 :			}
118 :			}
119 :
120 :			initially {Boid(i,initVelocities{i*2},initVelocities{i*2+1}) | i in 0 .. numBoids-1 };
121 :

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