多边形应以鼠标 x,y 为中心

Question

我写了多边形和圆形测试，其中通过光标，我围绕多边形 360 度旋转，针对中心点 x=0，y=0。

但是，我有一个问题，将多边形居中于鼠标 x,y 而不是边缘。就像现在在屏幕截图中一样，红色圆圈代表当前鼠标位置，绿色是我的目标。

我尝试使用 setOrigin 但这对我来说效果不佳或者我没有正确设置它。 附：忽略白色圆圈。

public class PolygonIntersectsCircle3Test extends AbstractTest {

    private Polygon polygon;
    private Circle circle;
    private boolean collides;

    public PolygonIntersectsCircle3Test(Game game) {
        super(game);
    }

    @Override
    public void create() {
        float width = 300f;
        float height = 50f;
        polygon = new Polygon(game, Color.WHITE_COLOR, new float[] {
            0, 0,
            width, 0,
            width, height,
            0, height
        }, 0);
        //polygon.setOrigin(width / 2, height / 2);
        circle = new Circle(game, Color.WHITE_COLOR, 100, 100, height / 2);
    }

    @Override
    public void update(float deltaTime) {
        Vector2 mouseRelativeToScreen = game.getInputController().getMouseRelativeToWorld();
        polygon.setPosition(mouseRelativeToScreen.x, mouseRelativeToScreen.y);
        float degrees = degrees(mouseRelativeToScreen.x, mouseRelativeToScreen.y, 0, 0);
        polygon.setRotation(degrees);
        collides = polygon.contains(circle.x, circle.y);
    }

    @Override
    public void draw() {
        game.getShapeRenderer().begin(ShapeRenderer.ShapeType.Line);
        if (collides) {
            game.getShapeRenderer().setColor(Color.RED);
        } else {
            game.getShapeRenderer().setColor(Color.WHITE_COLOR);
        }
        game.getShapeRenderer().polygon(polygon.getTransformedVertices());
        game.getShapeRenderer().circle(circle.x, circle.y, circle.radius);
        game.getShapeRenderer().end();
    }
}

  public static strictfp float degrees(float x, float y) {
        float degrees = (float) StrictMath.toDegrees(StrictMath.atan2(y, x));
        if (degrees < -360.0f || degrees > 360.0f) {
            degrees %= 360.0f;
        }
        if (degrees < 0.0f) {
            degrees += 360.0f;
        }
        return degrees;
    }

public static strictfp float degrees(float x, float y, float circleCenterX, float circleCenterY) {
    return angleInDegrees(x - circleCenterX, y - circleCenterY);
}

Answer 1

我以前从未使用过 LibGDX，但是 文档 似乎暗示多边形的原点可能打算用作顶点的原点，而不是转换的原点。如果是这样，您应该指定多边形的顶点，就好像它们都被多边形的中心点偏移：

float wd2 = width / 2.0f;
float hd2 = height / 2.0f;
polygon = new Polygon(game, Color.WHITE_COLOR, new float[] {
    -wd2, -hd2,
    wd2, -hd2,
    wd2, hd2,
    -wd2, hd2
}, 0);
polygon.setOrigin(0.0f, 0.0f); // I doubt this is necessary, but just in case