hfln_miniprogram/旋转矩形.js

/**
 * rect: [left, top, w, h]
 * radar: [radarX, radarY]
 * angle: 0, 90, 180, 270
 * 返回旋转后的矩形 [left, top, w, h]
 */
function rotateRect(rect, radar, angle) {
    const [left, top, w, h] = rect;
    const [cx, cy] = radar;

    // 矩形四个角
    const corners = [
        [left, top],
        [left + w, top],
        [left + w, top + h],
        [left, top + h]
    ];

    const newCorners = corners.map(([x, y]) => {
        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];
    });

    const xs = newCorners.map(p => p[0]);
    const ys = newCorners.map(p => p[1]);

    const newLeft = Math.min(...xs);
    const newTop = Math.min(...ys);
    const newW = Math.max(...xs) - newLeft;
    const newH = Math.max(...ys) - newTop;

    return [newLeft, newTop, newW, newH];
}

// 测试
const rect = [0, 0, 2, 1];
const radar = [2, 1];

[0, 90, 180, 270].forEach(angle => {
    const newRect = rotateRect(rect, radar, angle);
    console.log(`angle=${angle}:`, newRect);
});

// 预期输出
// angle=0: [0, 0, 2, 1]
// angle=90: [2, -1, 1, 2]
// angle=180: [2, 1, 2, 1]
// angle=270: [1, 1, 1, 2]