/*! \file flock.diderot * * \author Lamont Samuels * * This example is an implementation of Chris Reynolds Boids algorithm. It represents an example of using Spatial communication */ /* * COPYRIGHT (c) 2012 The Diderot Project (http://diderot-language.cs.uchicago.edu) * All rights reserved. */ real{} initVelocities = load("velocities.nrrd"); int numBoids = length(initVelocities)/2; int strandSize = 2; real query_radius = 50; int MAX_SPEED = 2; real MAX_FORCE = 0.05; int stepsMax = 10000; real boundsFactor = 10.0; input int width; input int height; int NORTH = 0; int SOUTH = 1; int WEST = 2; int EAST = 3; strand Boid(int i,real vx, real vy) { vec2 pos = [real(width)/2.0,real(height)/2.0]; vec2 vel = [vx,vy]; int steps = 0; int id = i; output vec4 boidInfo = [pos[0],pos[1],vel[0],vel[1]]; update { vec2 cohereVec = [0.0,0.0]; vec2 alignVec = [0.0,0.0]; vec2 seperateVec = [0.0,0.0]; vec4 wrapDimensions = [-boundsFactor, height + boundsFactor, -boundsFactor, width + boundsFactor]; int count = 0; foreach(Boid neighbor in sphere(query_radius)){ real d = dist(pos,neighbor.pos); if(d > 0) { cohereVec += neighbor.pos; alignVec += neighbor.vel; seperateVec = seperateVec + (normalize(pos-neighbor.pos)/d); count+=1; } } if(count > 0) { cohereVec /= real(count); alignVec /= real(count); seperateVec /= real(count); } real isZero = alignVec • alignVec; // limit the force if ( isZero != 0 && |alignVec| > MAX_FORCE) { alignVec = normalize(alignVec); alignVec *= MAX_FORCE; } vec2 diff = cohereVec - pos; isZero = cohereVec • cohereVec; if(|diff| > 0 && isZero != 0){ cohereVec = normalize(cohereVec); if(|diff| < 100.0) { cohereVec *= (MAX_SPEED*(|diff|/100.0)); }else { cohereVec *= MAX_SPEED; } cohereVec -= vel; // limit the force if (|cohereVec| > MAX_FORCE) { cohereVec = normalize(cohereVec); cohereVec *= MAX_FORCE; } } else{ cohereVec = [0.0,0.0]; } vec2 acceleration = cohereVec + alignVec + seperateVec; vel += acceleration; if (|vel| > MAX_SPEED){ vel = normalize(cohereVec); vel *= MAX_SPEED; } pos += vel; /* Wrapping Code, if a boid goes outside the window */ real posX = wrapDimensions[EAST] if pos[0] < wrapDimensions[WEST] else wrapDimensions[WEST] if pos[0] > wrapDimensions[EAST] else pos[0]; real posY = wrapDimensions[SOUTH] if pos[1] < wrapDimensions[NORTH] else wrapDimensions[NORTH] if pos[1] > wrapDimensions[SOUTH] else pos[1]; pos = [posX,posY]; boidInfo = [pos[0],pos[1], vel[0], vel[1]]; } } initially {Boid(i,initVelocities{i*2},initVelocities{i*2+1}) | i in 0 .. numBoids-1 };
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The output has ended thus: 1]]; } } initially {Boid(i,initVelocities{i*2},initVelocities{i*2+1}) | i in 0 .. numBoids-1 };