hfln_miniprogram/旋转点.js

/**
 * point: [x, y]
 * radar: [radarX, radarY]
 * angle: 0, 90, 180, 270 顺时针旋转角度
 * 返回旋转后的点 [x2, y2]
 */
function rotatePoint(point, radar, angle) {
    const [x, y] = point;
    const [cx, cy] = radar;
    const dx = x - cx;
    const dy = y - cy;
    let nx, ny;

    switch (angle) {
        case 0:
            nx = dx;
            ny = dy;
            break;
        case 90:
            nx = dy;
            ny = -dx;
            break;
        case 180:
            nx = -dx;
            ny = -dy;
            break;
        case 270:
            nx = -dy;
            ny = dx;
            break;
        default:
            throw new Error("angle must be 0, 90, 180, 270");
    }

    return [cx + nx, cy + ny];
}

// 测试
const point = [3, 2];
const radar = [2, 1];

[0, 90, 180, 270].forEach(angle => {
    const newPoint = rotatePoint(point, radar, angle);
    console.log(`angle=${angle}:`, newPoint);
});
// 预期输出
// angle=0: [3, 2]
// angle=90: [2, 0]
// angle=180: [1, 0]
// angle=270: [2, 2]