Question

我在WindowsForm上有两个矩形，我想检查它们是否发生碰撞。对于简单的非旋转碰撞，它看起来像这样：

Point newLocation; // upper-left corner of the object to check its collision
Size objectSize; // the object size
bool collision = false;

foreach (Object otherObject in otherObjects)
{
    if (newLocation.X >= otherObject.location.X && newLocation.X <= otherObject.location.X + otherObject.size.width)
        if (newLocation.Y >= otherObject.location.Y && newLocation.Y <= otherObject.location.Y + otherObject.size.height)
        {
            collision = true;
            break;
        }
}

但现在我用以下方式旋转了两个对象：

Matrix matrix = new Matrix();
matrix.RotateAt(angle, newLocation);
graphics.Transform = matrix;

如何检查旋转矩阵处的碰撞？我可以以某种方式获得翻译的X，Y坐标吗？

Answer 1

我有一些代码可以将点从标准坐标系转移到特定的坐标系（但在这种情况下，Y会增加屏幕中的下降，因此会进行一些调整并进行评论。）

这里，double []表示一个点，其中索引0是X坐标，索引1是Y. 请注意，新坐标系的角度是逆时针和弧度。（乘以Pi / 180将度数转换为弧度）。

    /// <summary>
    /// Implemented - Returns the point coordinates related to a new coordinate system
    /// Does not change original point
    /// </summary>
    /// <param name="Point">Point to be returned in new coordinate system</param>
    /// <param name="NewSystemCouterClockRotation">CounterClokWise Angle of rotation of the new coordinate system compared to the current, measured in radians</param>
    /// <param name="NewSystemOrigin">Location of the new origin point in the current coordinate system</param>
    /// <returns></returns>
    public double[] ChangeCoordinateSystem(double[] Point, double NewSystemCouterClockRotation, double[] NewSystemOrigin)
    {

        //first adjust: fix that winform downwards increasing Y before applying the method
        Point[1] = -Point[1];
        NewSystemOrigin[1] = -NewSystemOrigin[1]

        //end of first adjust


        //original method
        double[] Displacement = new double[2] { Point[0] - NewSystemOrigin[0], Point[1] - NewSystemOrigin[1] };


        double[] Result = new double[2]
        {
            + Displacement[0] * Math.Cos(NewSystemCouterClockRotation) + Displacement[1] * Math.Sin(NewSystemCouterClockRotation), 
            - Displacement[0] * Math.Sin(NewSystemCouterClockRotation) + Displacement[1] * Math.Cos(NewSystemCouterClockRotation) 
        }; 

        //second adjust: reset Y of the result
        Result[1] = - Result[1];

        return Result;
    }

但是，如果你的两个物体有不同的角度，你应该小心，最好的方法是检查第一个矩形的all four corners of the first是否不在另一个物体内，如果the other object four corners不在第一个内部。

可以在这里找到一些algorythm来找出一个点是否在多边形内： Point in polygon

如何检查旋转对象的平移点碰撞？

1 个答案: