來自兩個關節的DrawEllipse（點，或者X和Y坐標）

Question

我希望按橢圓而不是按行顯示骨架。 我有兩個坐標為X和Y的點。當我想繪制一個橢圓時，我需要

public abstract void DrawEllipse(
Brush brush,
Pen pen,
Point center,
double radiusX,
double radiusY

）

所以我已經嘗試過使用此代碼，但是有一些錯誤（不知道radiusY）：

 double centerX = (jointPoints[jointType0].X + jointPoints[jointType1].X) / 2;
        double centerY = (jointPoints[jointType0].Y + jointPoints[jointType1].Y) / 2;
        double radiusX =Math.Sqrt( (Math.Pow((jointPoints[jointType1].X - jointPoints[jointType0].X), 2)) + (Math.Pow((jointPoints[jointType1].Y - jointPoints[jointType0].Y), 2)));
        drawingContext.DrawEllipse(null, drawPen, new Point(centerX, centerY), radiusX, radiusX/5);

誰能幫我？

private void DrawBone(IReadOnlyDictionary<JointType, Joint> joints, IDictionary<JointType, Point> jointPoints, JointType jointType0, JointType jointType1, DrawingContext drawingContext, Pen drawingPen,List<JointType> badJoint)
    {
        Joint joint0 = joints[jointType0];
        Joint joint1 = joints[jointType1];

        // If we can't find either of these joints, exit
        if (joint0.TrackingState == TrackingState.NotTracked ||
            joint1.TrackingState == TrackingState.NotTracked)
        {
            return;
        }



        // We assume all drawn bones are inferred unless BOTH joints are tracked
        Pen drawPen = this.inferredBonePen;

        if ((joint0.TrackingState == TrackingState.Tracked) && (joint1.TrackingState == TrackingState.Tracked))
        {
            drawPen = drawingPen;
        }
        //If a bone makes parts of an one bad angle respect reference angle
        if (badJoint.Contains(jointType0) && badJoint.Contains(jointType0))
            drawPen = new Pen(Brushes.Red, 6);
        drawingContext.DrawLine(drawPen, jointPoints[jointType0], jointPoints[jointType1]);

Answer 1

您不能（只是）使用DrawEllipse方法，因為它將始終繪制水平或垂直橢圓。

使用以下代碼實現旋轉： https : //stackoverflow.com/a/5298921/1974021並編寫一個采用以下輸入參數的方法：

1. Focalpoint1
2. FocalPoint2
3. 半徑

橢圓可以通過焦點和（組合）半徑來描述。 如果使用焦點，則省略號將在關節處重疊，從而在每個關節處創建一個圓形圖案。 那就是你想要的嗎？ （如果只希望他們觸摸關節，這會更加容易）

好的，它實際上不是焦點，而是圓弧的中心。 試試這個方法：

private static void DrawEllipse(Pen pen, Graphics g, PointF pointA, PointF pointB, float radius)
{
    var center = new PointF((pointA.X + pointB.X) / 2, (pointA.Y + pointB.Y) / 2);
    var distance = GetDistance(pointA, pointB);

    // The axis are calculated so that the center of the osculating circles are conincident with the points and has the given radius.
    var a = radius + distance / 2; // Semi-major axis
    var b = (float)Math.Sqrt(radius * a); // Semi-minor axis


    // Angle in degrees
    float angle = (float)(Math.Atan2(pointA.Y - pointB.Y, pointA.X - pointB.X) * 180 / Math.PI);
    using (Matrix rotate = new Matrix())
    {
        GraphicsContainer container = g.BeginContainer();
        rotate.RotateAt(angle, center);
        g.Transform = rotate;
        g.DrawEllipse(pen, center.X-a, center.Y-b, 2 * a, 2 * b);
        g.EndContainer(container);
    }
}

private static float GetDistance(PointF a, PointF b)
{
    var dx = a.X - b.X;
    var dy = a.Y - b.Y;
    return (float)Math.Sqrt(dx * dx + dy * dy);
}