LightningChart Support Forums

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private void chart_MouseMove(object sender, MouseEventArgs e)
        {
            Point mouseScreen = e.GetPosition(m_chart);
        
            //Seek from data series 
            int iNearestIndex = GetNearestIndexToMouse(m_chart.View3D.PointLineSeries3D[0], mouseScreen.X, mouseScreen.Y);

            if (iNearestIndex >= 0)
            {
                PointDouble3D nearestPoint = m_chart.View3D.PointLineSeries3D[0].Points[iNearestIndex]; 
                
                m_chart.BeginUpdate();

                //Create another PointLineSeries to show the nearest point with a box. 
                if(m_chart.View3D.PointLineSeries3D.Count < 2)
                {
                    PointLineSeries3D marker = new PointLineSeries3D(m_chart.View3D, Axis3DBinding.Primary, Axis3DBinding.Primary, Axis3DBinding.Primary);
                    marker.PointStyle.Shape = PointShape3D.Box;
                    marker.PointStyle.Size.SetValues(4, 4, 4);
                    marker.Material.DiffuseColor = Color.Lime; 
                    marker.MouseInteraction = false; 
                    m_chart.View3D.PointLineSeries3D.Add(marker); 

                }

                m_chart.View3D.PointLineSeries3D[1].Points = new PointDouble3D[] { nearestPoint };

                m_chart.EndUpdate(); 
            }
       }

int GetNearestIndexToMouse(PointLineSeries3D pls, double mouseX, double mouseY)
        {
         
            PointDouble3D[] points = pls.Points;
            int iPointCount = pls.PointCount;
            PointInt p;
            
            double dMinDistSq = double.MaxValue;
            int iNearestIndex = -1;
            double dDistSq; 
            double x, y;

            //Seek nearest point, by using squared method. It's faster than calling Sqrt every time. 

            for(int i=0;i<iPointCount;i++)
            {
                p = m_chart.View3D.ConvertSeriesValueToScreenCoord(pls, points[i].X, points[i].Y, points[i].Z);
                x = (double) p.X;
                y = (double) p.Y;

                dDistSq = (y - mouseY) * (y - mouseY) + (x - mouseX) * (x - mouseX);
                if (dDistSq < dMinDistSq)
                {
                    dMinDistSq = dDistSq;
                    iNearestIndex = i;
                }
            }

            return iNearestIndex; 

        }