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Alexander Rose authored
- ensure lines & points are at least 1 pixel big - look around center pixel in a spiral for hits
Alexander Rose authored- ensure lines & points are at least 1 pixel big - look around center pixel in a spiral for hits
misc.ts 1.67 KiB
/**
* Copyright (c) 2018-2021 mol* contributors, licensed under MIT, See LICENSE file for more info.
*
* @author Alexander Rose <alexander.rose@weirdbyte.de>
*/
export const halfPI = Math.PI / 2;
export const PiDiv180 = Math.PI / 180;
export function degToRad(deg: number) {
return deg * PiDiv180; // deg * Math.PI / 180
}
export function radToDeg(rad: number) {
return rad / PiDiv180; // rad * 180 / Math.PI
}
export function isPowerOfTwo(x: number) {
return (x !== 0) && (x & (x - 1)) === 0;
}
/** return the value that has the largest absolute value */
export function absMax(...values: number[]) {
let max = 0;
let absMax = 0;
for (let i = 0, il = values.length; i < il; ++i) {
const value = values[i];
const abs = Math.abs(value);
if (abs > absMax) {
max = value;
absMax = abs;
}
}
return max;
}
/** Length of an arc with angle in radians */
export function arcLength(angle: number, radius: number) {
return angle * radius;
}
/** Create an outward spiral of given `radius` on a 2d grid */
export function spiral2d(radius: number) {
let x = 0;
let y = 0;
const delta = [0, -1];
const size = radius * 2 + 1;
const halfSize = size / 2;
const out: [number, number][] = [];
for (let i = Math.pow(size, 2); i > 0; --i) {
if ((-halfSize < x && x <= halfSize) && (-halfSize < y && y <= halfSize)) {
out.push([x, y]);
}
if (x === y || (x < 0 && x === -y) || (x > 0 && x === 1 - y)) {
[delta[0], delta[1]] = [-delta[1], delta[0]]; // change direction
}
x += delta[0];
y += delta[1];
}
return out;
}