Java中的旋转矩形 [英] Rotate Rectangle in Java

问题描述

我需要创建围绕其中心旋转的矩形(因此它们不需要平行于坐标系的轴).所以基本上每个矩形都可以由 center-X、center-Y、width、height 和 定义>角度.然后我想做的是计算某些点是否包含在这些矩形中(因此不涉及绘图).我想我不能使用 Rectangle2D 类，因为这些矩形总是平行于坐标系的 x 和 y 轴.是通过编写我自己的矩形类来获得此功能的唯一方法，还是我可以使用现有的任何东西(类似于 Rectangle2D)?

I need to create rectangles that are rotated around their center (so they don't need to be parallel to the axes of the coordinate system). So basicelly each rectangle can be defined by center-X, center-Y, width, height and angle. What I want to do then is to perform calculations on whether certain points are contained in these rectangles or not (so no drawing will be involved). I guess I cant use the Rectangle2D class because these rectangles will always be parallel to the x and y-axis of the coordinate system. Is the only way to get this functionality by writing my own rectangle class or is there anything existing (similar to Rectangle2D) I can use?

推荐答案

旋转所有要测试的点，像米海一样使用 Rectangle2D 的 contains(Point) 方法.

Rotate all the points you want to test and use contains(Point) method of the Rectangle2D as Mihai did.

但如果你真的想旋转矩形，你可以这样做(这是整数版本，但也许你也可以用 Rectangle2D 来做 :)).

But if you really want to rotate the rectangles you can do it like this (this is the integer version but probably you can do it with Rectangle2D aswell :)).

public class TestRotate {
    public static void main(String... args) {

        Rectangle r = new Rectangle(50, 50, 100, 100);
        Point check = new Point(100, 151); // clearly outside

        System.out.println("first: " + r.contains(check));

        AffineTransform at = AffineTransform.getRotateInstance(
                Math.PI/4, r.getCenterX(), r.getCenterY());

        Polygon p = new Polygon(); 

        PathIterator i = r.getPathIterator(at);
        while (!i.isDone()) {
            double[] xy = new double[2];
            i.currentSegment(xy);
            p.addPoint((int) xy[0], (int) xy[1]);
            System.out.println(Arrays.toString(xy));

            i.next();
        }

        // should now be inside :)
        System.out.println("second: " + p.contains(check));
    }
}

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