pocket-physics/esm/v2.js

Verlet physics extracted from pocket-ces demos

export function v2(x, y) {
    return { x: x || 0, y: y || 0 };
}
export const copy = (out, a) => {
    out.x = a.x;
    out.y = a.y;
    return out;
};
export const set = (out, x, y) => {
    out.x = x;
    out.y = y;
    return out;
};
export const add = (out, a, b) => {
    out.x = (a.x + b.x);
    out.y = (a.y + b.y);
    return out;
};
export const sub = (out, a, b) => {
    out.x = (a.x - b.x);
    out.y = (a.y - b.y);
    return out;
};
export const dot = (a, b) => a.x * b.x + a.y * b.y;
export const scale = (out, a, factor) => {
    out.x = (a.x * factor);
    out.y = (a.y * factor);
    return out;
};
export const distance = (v1, v2) => {
    const x = v1.x - v2.x;
    const y = v1.y - v2.y;
    return Math.sqrt(x * x + y * y);
};
export const distance2 = (v1, v2) => {
    const x = v1.x - v2.x;
    const y = v1.y - v2.y;
    return x * x + y * y;
};
export const magnitude = (v1) => {
    const x = v1.x;
    const y = v1.y;
    return Math.sqrt(x * x + y * y);
};
export const normalize = (out, a) => {
    const x = a.x;
    const y = a.y;
    let len = x * x + y * y;
    if (len > 0) {
        len = 1 / Math.sqrt(len);
        out.x = (a.x * len);
        out.y = (a.y * len);
    }
    return out;
};
/**
 * Compute the normal pointing away perpendicular from two vectors.
 * Given v1(0,0) -> v2(10, 0), the normal will be (0, 1)
 * */
export const normal = (out, v1, v2) => {
    out.y = (v2.x - v1.x);
    out.x = (v1.y - v2.y);
    return normalize(out, out);
};
// the perpendicular dot product, also known as "cross" elsewhere
// http://stackoverflow.com/a/243977/169491
export const perpDot = (v1, v2) => {
    return v1.x * v2.y - v1.y * v2.x;
};
/**
 * This is mostly useful for moving a verlet-style [current, previous]
 * by the same amount, translating them while preserving velocity.
 * @param by the vector to add to each subsequent vector
 * @param vN any number of vectors to translate
 */
export const translate = (by, ...vN) => {
    for (let i = 0; i < vN.length; i++) {
        const v = vN[i];
        add(v, v, by);
    }
};
/**
 *
 * @param v Print this vector for nice logs
 */
export function vd(v) {
    return `(${v.x}, ${v.y})`;
}
/**
 * Rotate a vector around another point. Taken nearly verbatim from gl-matrix
 */
export const rotate2d = (out, target, origin, rad) => {
    //Translate point to the origin
    const p0 = target.x - origin.x;
    const p1 = target.y - origin.y;
    const sinC = Math.sin(rad);
    const cosC = Math.cos(rad);
    //perform rotation and translate to correct position
    out.x = p0 * cosC - p1 * sinC + origin.x;
    out.y = p0 * sinC + p1 * cosC + origin.y;
    return out;
};
/**
 * Compute the Theta angle between a vector and the origin.
 */
export function angleOf(v) {
    return Math.atan2(v.y, v.x);
}