ridder/dist/rectangle.js

A straightforward game engine for simple data-driven games in JavaScript

import { random } from "./utils.js";
import { getVectorLength, setVector } from "./vector.js";
/**
 * Create a new rectangle data structure.
 * @param x - The x-coordinate.
 * @param y - The y-coordinate.
 * @param w - The width.
 * @param h - The height.
 */
export function rect(x = 0, y = 0, w = 0, h = 0) {
    return { x, y, w, h };
}
/**
 * Set the components of the rectangle and returns the rectangle.
 */
export function setRectangle(r, x, y, w, h) {
    r.x = x;
    r.y = y;
    r.w = w;
    r.h = h;
    return r;
}
/**
 * Returns `true` if the rectangle has a width and height larger than 0.
 */
export function isRectangleValid(r) {
    return r.w > 0 && r.h > 0;
}
/**
 * Returns `true` when the rectangles {@link a} and {@link b} intersect (overlap).
 */
export function doRectanglesIntersect(a, b) {
    if (a === b || !isRectangleValid(a) || !isRectangleValid(b)) {
        return false;
    }
    return a.x < b.x + b.w && a.x + a.w > b.x && a.y < b.y + b.h && a.y + a.h > b.y;
}
/**
 * Returns `true` when {@link x} and {@link y} are inside the rectangle {@link r}.
 */
export function doesRectangleContain(r, x, y) {
    return x > r.x && x < r.x + r.w && y > r.y && y < r.y + r.h;
}
/**
 * Write the intersection (overlap) result between the rectangles {@link a} and {@link b} into the vector {@link out}.
 *
 * NOTE - This does not reset the vector {@link out} so this function can be used to accumulate the intersection result.
 *
 * @see {@link https://github.com/patrickswijgman/ridder/blob/main/examples/platformer/index.ts#L136} for an example.
 *
 * @param velocity - The velocity of rectangle {@link a}
 */
export function writeIntersectionBetweenRectangles(a, b, velocity, out) {
    if (!getVectorLength(velocity) || !doRectanglesIntersect(a, b)) {
        return out;
    }
    const l = a.x + a.w - b.x;
    const r = b.x + b.w - a.x;
    const u = a.y + a.h - b.y;
    const d = b.y + b.h - a.y;
    switch (true) {
        case velocity.x > 0 && velocity.y > 0:
            if (l > u) {
                out.y -= u;
            }
            else {
                out.x -= l;
            }
            break;
        case velocity.x < 0 && velocity.y > 0:
            if (r > u) {
                out.y -= u;
            }
            else {
                out.x += r;
            }
            break;
        case velocity.x > 0 && velocity.y < 0:
            if (l > d) {
                out.y += d;
            }
            else {
                out.x -= l;
            }
            break;
        case velocity.x < 0 && velocity.y < 0:
            if (r > d) {
                out.y += d;
            }
            else {
                out.x += r;
            }
            break;
        case velocity.x > 0:
            out.x -= l;
            break;
        case velocity.x < 0:
            out.x += r;
            break;
        case velocity.y > 0:
            out.y -= u;
            break;
        case velocity.y < 0:
            out.y += d;
            break;
    }
    return out;
}
/**
 * Write the result of a random point between the inner and outer rectangles.
 */
export function writeRandomPointInPerimeterBetweenRectangles(outer, inner, out) {
    let x = 0;
    let y = 0;
    const region = random(0, 3);
    switch (region) {
        case 0:
            x = random(outer.x, outer.x + outer.w);
            y = random(outer.y, inner.y);
            break;
        case 1:
            x = random(outer.x, outer.x + outer.w);
            y = random(inner.y + inner.h, outer.y + outer.h);
            break;
        case 2:
            x = random(outer.x, inner.x);
            y = random(inner.y, inner.y + inner.h);
            break;
        case 3:
            x = random(inner.x + inner.w, outer.x + outer.w);
            y = random(inner.y, inner.y + inner.h);
            break;
    }
    setVector(out, x, y);
}
/**
 * Copy the data components of rectangle {@link b} into rectangle {@link a} and returns rectangle {@link a}.
 */
export function copyRectangle(a, b) {
    a.x = b.x;
    a.y = b.y;
    a.w = b.w;
    a.h = b.h;
    return a;
}