C# SolidWorks 二次开发 API --- 把零件中的坐标点转换到总装配中

今天我们来看下solidworks中的坐标矩阵转换，这个例子是把子零件中的一个基准轴的两个端点读出来，并转换到总装配的坐标系中，得到在总装配体坐标系的位置，可以进一步判断轴的真实安装方向。

直接上代码：

 private void btn_Transform_PartToAsm_Click(object sender, EventArgs e)
        {
            //连接到Solidworks

            //这个例子是把零件中的一个基准轴 的两个点的坐标转换到装配体中

            //请打开装配体，并在某个零件下选择一下基准轴

            ISldWorks swApp = Utility.ConnectToSolidWorks();

            ModelDoc2 swModel = (ModelDoc2)swApp.ActiveDoc;

            SelectionMgr swSelMgr = swModel.ISelectionManager;

            Feature swFeat = (Feature)swSelMgr.GetSelectedObject6(1, 0);

            String sAxisName = swFeat.Name;

            RefAxis RefAxis = swFeat.GetSpecificFeature2();

            var vParam = RefAxis.GetRefAxisParams();

            Component2 inletPart = swSelMgr.GetSelectedObjectsComponent4(1, 0);

            double[] nPt = new double[3];
            double[] nPt2 = new double[3];

            object vPt;
            object vPt2;

            nPt[0] = vParam[0]; nPt[1] = vParam[1]; nPt[2] = vParam[2];
            nPt2[0] = vParam[3]; nPt2[1] = vParam[4]; nPt2[2] = vParam[5];

            vPt = nPt;
            vPt2 = nPt2;

            MathUtility swMathUtil = (MathUtility)swApp.GetMathUtility();

            MathTransform mathTransform = inletPart.Transform2;

            MathTransform swXform = (MathTransform)mathTransform;

            MathPoint swMathPt = (MathPoint)swMathUtil.CreatePoint((vPt));

            MathPoint swMathPt2 = (MathPoint)swMathUtil.CreatePoint((vPt2));

            //swXform.Inverse(); 反转的话就是把装配体中的点坐标转到零件对应的坐标系统中

            swMathPt = (MathPoint)swMathPt.MultiplyTransform(swXform);

            swMathPt2 = (MathPoint)swMathPt2.MultiplyTransform(swXform);

            var x = swMathPt.ArrayData[0];
            var y = swMathPt.ArrayData[1];
            var z = swMathPt.ArrayData[2];
            var x2 = swMathPt2.ArrayData[0];
            var y2 = swMathPt2.ArrayData[1];
            var z2 = swMathPt2.ArrayData[2];

            var v1 = x2 - x;
            var v2 = y2 - y;
            var v3 = z2 - z;

            if (Math.Round(v3, 4) != 0 && Math.Round(v1, 4) == 0 && Math.Round(v2, 4) == 0)
            {
                MessageBox.Show("此轴在Z方向上");
            }

          
        }

比较全的关于矩阵转换的一篇文章：

https://cadbooster.com/complete-overview-of-matrix-transformations-in-the-solidworks-api/#available-transformations-solidworks