在Java中旋转矩形 [英] Rotate Rectangle in Java

问题描述

我需要创建围绕其中心旋转的矩形（因此它们不需要与坐标系的轴平行）。所以basicelly每个矩形可以由 center-X ， center-Y ， width ， height 和角度即可。我想要做的是对这些矩形中是否包含某些点进行计算（因此不会涉及绘图）。我想我不能使用 Rectangle2D 类，因为这些矩形将始终与坐标系的x和y轴平行。是通过编写我自己的矩形类来获得此功能的唯一方法，还是存在任何现有的（类似于 Rectangle2D ）我可以使用？

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

旋转你要测试的所有点，并使用Rectangle2D的contains（Point）方法作为Mihai。

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

但是如果你真的想要旋转矩形你就可以这样做（这是整数版本，但是你可以用Rectangle2D做它：））。

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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