lemmings/utils.js

"use strict"
const Vec2 = {
    add({x:x1, y:y1}, {x:x2, y:y2}) {
        return Object.freeze({x:x1+x2, y:y1+y2})
    },
    avg({x:x1, y:y1}, {x:x2, y:y2}) {
        return Object.freeze({x:(x1+x2)/2, y:(y1+y2)/2})
    },
    fromPolar({x,y}, radius, angle) {
        return Object.freeze({x: x + radius * Math.cos(angle),
                              y: y + radius * Math.sin(angle)})
    },
    sub({x:x1, y:y1}, {x:x2, y:y2}) {
        return Object.freeze({x:x1-x2, y: y1-y2})
    },
    angle({x, y}) {
        return Math.atan2(y, x)
    },
    len({x, y}) {
        return Math.sqrt((x*x) + (y*y))
    },
    dist(a, b) {
        return Vec2.len(Vec2.sub(a, b))
    },
    distLess(a, b, radius) {
        const {x, y} = Vec2.sub(a, b)
        return ((x*x) + (y*y)) < (radius * radius)
    },
    zero: Object.freeze({x:0, y:0})
};

function drawVertices(context, vertices, draw=true, close=true) {
    if (draw) context.beginPath();
    context.moveTo(vertices[0].x, vertices[0].y);
    vertices.slice(1).forEach(({x, y}) =>
                              context.lineTo(x, y))
    if (close) context.lineTo(vertices[0].x, vertices[0].y);
    if (draw) context.stroke();
}

function convrgb(values) {
    return 'rgb(' + values.map(x=>x|0).join(', ') + ')';
};

// apply mild noise on the sensor reading, and clamp between valid values
function gaussNoise(sigma=1) {
    const x0 = 1.0 - Math.random();
    const x1 = 1.0 - Math.random();
    return sigma * Math.sqrt(-2 * Math.log(x0)) * Math.cos(2 * Math.PI * x1);
};
const zip = (arr, ...arrs) => {
  return arr.map((val, i) => arrs.reduce((a, arr) => [...a, arr[i]], [val]));
}
const sum = (arr) => arr.reduce((a,b) => a+b)