80 lines
1.9 KiB
JavaScript
80 lines
1.9 KiB
JavaScript
import Vector from './vector.mjs';
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const findNeighbors = (boids, boid, radius) =>
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{
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const neighbors = [];
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for (let otherBoid of boids)
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{
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if (boid != otherBoid)
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{
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const dist = boid.pos.sub(otherBoid.pos).normSquared();
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if (dist < radius * radius)
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{
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neighbors.push(otherBoid);
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}
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}
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}
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return neighbors;
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};
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export const update = (boids, params, time) =>
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{
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for (let boid of boids)
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{
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const visible = findNeighbors(boids, boid, params.visibleDist);
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const close = findNeighbors(boids, boid, params.closeDist);
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// Attract towards center of visible flock
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const center = new Vector(0, 0);
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for (let otherBoid of visible)
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{
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center.addMut(otherBoid.pos);
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}
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if (visible.length >= 1)
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{
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center.divMut(visible.length);
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boid.vel.addMut(center.sub(boid.pos).mul(params.centerAccel));
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}
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// Attract toward center of screen
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boid.vel.addMut(boid.pos.mul(-0.01));
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// Repel away from close boids
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for (let otherBoid of close)
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{
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boid.vel.addMut(boid.pos
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.sub(otherBoid.pos)
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.mul(params.repelAccel));
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}
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// Match other boids’ velocity
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const velocity = new Vector(0, 0);
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for (let otherBoid of visible)
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{
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velocity.addMut(otherBoid.vel);
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}
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if (visible.length >= 1)
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{
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velocity.divMut(visible.length);
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boid.vel.addMut(velocity.sub(boid.vel).mul(params.matchAccel));
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}
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// Do not surpass maximum speed
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const speed = boid.vel.normSquared();
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if (speed > params.maxSpeed * params.maxSpeed)
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{
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boid.vel.divMut(Math.sqrt(speed)).mulMut(params.maxSpeed);
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}
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boid.pos.addMut(boid.vel.mul(time));
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}
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};
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