76 lines
2.0 KiB
JavaScript
76 lines
2.0 KiB
JavaScript
import Vector from './vector.mjs';
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const meanPos = new Vector(0, 0);
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const meanVel = new Vector(0, 0);
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const repelForce = new Vector(0, 0);
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export const update = (boids, params, time) =>
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{
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const boidsSize = boids.length;
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for (let i = 0; i < boidsSize; ++i)
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{
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const me = boids[i];
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meanPos.reset();
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meanVel.reset();
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repelForce.reset();
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let visibleSize = 0;
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for (let j = 0; j < boidsSize; ++j)
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{
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if (i != j)
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{
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const you = boids[j];
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const dist = Vector.distSquared(me.pos, you.pos);
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if (dist < params.visibleDist * params.visibleDist)
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{
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meanPos.add(you.pos);
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meanVel.add(you.vel);
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visibleSize += 1;
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if (dist < params.closeDist * params.closeDist)
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{
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repelForce.add(me.pos).sub(you.pos);
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}
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}
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}
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}
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// Attract towards center of visible flock
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if (visibleSize >= 1)
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{
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me.vel.add(meanPos.div(visibleSize)
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.sub(me.pos)
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.mul(params.centerAccel));
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}
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// Attract toward center of screen
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me.vel.addMul(me.pos, -0.01);
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// Repel away from close boids
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me.vel.add(repelForce.mul(params.repelAccel));
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// Match other boids’ velocity
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if (visibleSize >= 1)
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{
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me.vel.add(meanVel.div(visibleSize)
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.sub(me.vel)
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.mul(params.matchAccel));
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}
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// Do not surpass maximum speed
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const speed = me.vel.normSquared();
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if (speed > params.maxSpeed * params.maxSpeed)
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{
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me.vel.div(Math.sqrt(speed)).mul(params.maxSpeed);
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}
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// Integrate speed
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me.pos.addMul(me.vel, time);
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}
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};
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