Sphere/Cuboid Collision

logic.ts

function getAABB(rect: Cuboid) {
    const result = {
        min: [rect.x, rect.y, rect.z],
        max: [rect.x + rect.w, rect.y + rect.h, rect.z + rect.d],
    };

    // Swap the vertices if the min/max is reversed
    // because of orientation or whatever.
    for (let i = 0; i < 3; i++) {
        if (result.max[i] < result.min[i]) {
            // Swap
            const a = result.min[i];
            result.min[i] = result.max[i];
            result.max[i] = a;
        }
    }
    
    return result;
}

function squaredDistPointAABB(sphere: Sphere, rect: Cuboid) {
    let sqDist = 0;
    const p = [sphere.x, sphere.y, sphere.z];
    const b = getAABB(rect);

    for (let i = 0; i < 3; i++) {
        // for each axis count any excess distance outside box extents
        let v = p[i];
        if (v < b.min[i]) sqDist += (b.min[i] - v) * (b.min[i] - v);
        if (v > b.max[i]) sqDist += (v - b.max[i]) * (v - b.max[i]);
    }
    return sqDist;
}

export function sphereRectCollision(
    sphere: Sphere,
    rect: Cuboid
): [boolean, number] {
    // Compute squared distance between sphere center and AABB
    // the sqrt(dist) is fine to use as well, but this is faster.
    let sqDist = squaredDistPointAABB(sphere, rect);

    // Sphere and AABB intersect if the (squared) distance between them is
    // less than the (squared) sphere radius.
    return [sqDist <= sphere.radius * sphere.radius, sqDist];
}