在java中旋转矩形对象
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Rotating the Rectangle object in java
提问by Chris
Is it possible to rotate the Rectangleobject to a certain degree around it's axis? Is it as easy as Rectangle rect = new Rectangle(x,y,w,h,r)?
是否可以将Rectangle对象围绕其轴旋转一定程度？有那么容易Rectangle rect = new Rectangle(x,y,w,h,r)吗？
If it is not possible to rotate the object, what would be a way I could get similar results?
如果无法旋转对象，我可以获得类似结果的方法是什么？
Edit:for clarity here is my dilemma, I have images that rotate but when they colide with other images the collisions only work at 90 and 180 degree rotations because their hit box Rectangle objects don't rotate.
编辑：为了清楚起见，这是我的困境，我有旋转的图像，但是当它们与其他图像碰撞时，碰撞仅在 90 度和 180 度旋转时起作用，因为它们的命中框 Rectangle 对象不旋转。
采纳答案by Hovercraft Full Of Eels
Edit: for clarity here is my dilemma, I have images that rotate but when they colide with other images the collisions only work at 90 and 180 degree rotations because their hit box Rectangle objects don't rotate.
编辑：为了清楚起见，这是我的困境，我有旋转的图像，但是当它们与其他图像碰撞时，碰撞仅在 90 度和 180 度旋转时起作用，因为它们的命中框 Rectangle 对象不旋转。
You can rotate a Shape-derived object, such as a Rectangle2D by using the AffineTransform method, createTransformedShape(...).
您可以使用 AffineTransform 方法旋转 Shape 派生对象，例如 Rectangle2D createTransformedShape(...)。
Rectangle2D myRect = new Rectangle2D.Double(100, 100, 200, 200);
AffineTransform at = AffineTransform.getRotateInstance(Math.PI / 4, 150, 150);
Shape rotatedRect = at.createTransformedShape(myRect);
Note: code not compiled nor tested.
注意：代码未编译或测试。
回答by tbodt
To rotate the rectangle, you give the graphics context an AffineTransformfor rotation. Here's an example:
要旋转矩形，您可以为图形上下文指定AffineTransform旋转。下面是一个例子：
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
AffineTransform oldTransform = g2d.getTransform();
g2d.setTransform(AffineTransform.getRotateInstance(radians);
g2d.draw(rectangle);
g2d.setTransform(oldTransform);
}
You can also use g2d.rotate(radians)for rotation.
您也可以g2d.rotate(radians)用于旋转。
Note that the angle must be in radians. To convert degrees into radians, use degrees * (Math.PI/180)for the angle.
请注意，角度必须以弧度为单位。要将度数转换为弧度，请使用degrees * (Math.PI/180)角度。
回答by Radiodef
There's also another way to do this (besides createTransformedShape) which creates fewer temporary objects, if that's desirable.
如果需要，还有另一种方法可以做到这一点（除此之外createTransformedShape），它会创建更少的临时对象。
Instead of keeping a Rectangle2Dfor the bounding box, you can keep a Path2Dand then do the transform in place, using Path2D.transform(AffineTransform):
Rectangle2D您可以保留 aPath2D然后使用Path2D.transform(AffineTransform)以下方法进行变换，而不是为边界框保留 a ：
import java.awt.geom.*;
public class Example {
private final Path2D hitBox;
public Example(Rectangle2D initialHitBox) {
this.hitBox = new Path2D.Double(initialHitBox);
}
public void transform(AffineTransform tx) {
path.transform(tx); // In-place transformation.
}
// ...
}
This is very similar to what AffineTransformactually does under the hood.
这是非常相似的东西AffineTransform引擎盖下实际执行。
