Navisworks .NET API 2013 new feature – Viewpoint 1

By Xiaodong Liang

ViewPoint is how eyes look at the model. In the past, we need to use COM API to access viewpoint and camera. 2013 .NET API provides the relevant object Viewpoint.

Viewpoint represents the anonymous viewpoint, containing the properties such as near plane distance, far plane distance, linear speed, angular speed etc. It also includes the abilities to manipulate the camera directly. The current viewpoint is accessed by DocumentCurrentViewpoint.

One particular property of Viewpoint is Rotation, which is an object Roation3D. It defines a quaternion to configure the behaviors of the camera.

Note: in current release, API does not provide the property of view direction and the method to multiply two quaternion. While they can be achieved with the theory of quaternion, using Roation3D. The following code snippet dumps the properties of current view point. It also demos how to get view direction. A help method MultiplyRotation3D is to multiply quaternion. 

using System.Diagnostics;      using Autodesk.Navisworks.Api;    using Autodesk.Navisworks.Api.Plugins;

private void dumpViewPoint()    {        Document oDoc =             Autodesk.Navisworks.Api.Application.ActiveDocument;        // get current viewpoint         Viewpoint oCurVP = oDoc.CurrentViewpoint;             // common properties        Debug.Print("Far Plane Distance: " +                 oCurVP.FarPlaneDistance);        Debug.Print("Near Plane Distance: " +                 oCurVP.NearPlaneDistance);        Debug.Print("Projection: " +                 oCurVP.Projection);        Debug.Print("Aspect Ratio: " +                 oCurVP.AspectRatio);                  if (oCurVP.HasLinearSpeed)            Debug.Print("Linear Speed: " +                 oCurVP.LinearSpeed);        else            Debug.Print("Linear Speed: ");        if (oCurVP.HasAngularSpeed)            Debug.Print("Angular Speed: " +                 oCurVP.AngularSpeed);        else            Debug.Print("Angular Speed: ");        if (oCurVP.HasLighting)            Debug.Print("Lighting: " +                oCurVP.Lighting);        else            Debug.Print("Lighting: ");             if (oCurVP.HasRenderStyle)            Debug.Print("RenderStyle: " +                 oCurVP.RenderStyle);        else            Debug.Print("RenderStyle: " +                 oCurVP.RenderStyle);             if (oCurVP.HasTool)            Debug.Print("Tool: " +                 oCurVP.Tool);        else            Debug.Print("Tool: " +                 oCurVP.Tool);                  // camera properties        double oFocal =             oCurVP.FocalDistance;        Debug.Print("Focal Distance: " +            oFocal);      &
#160; // Rotation        Rotation3D oRot = oCurVP.Rotation;        Debug.Print(            "Quaternion:  = ",                      oRot.A,                      oRot.B,                      oRot.C,                      oRot.D);             // calculate view direction        Rotation3D oNegtiveZ =             new Rotation3D(0, 0, -1, 0);        Rotation3D otempRot =             MultiplyRotation3D(oNegtiveZ, oRot.Invert());        Rotation3D oViewDirRot =            MultiplyRotation3D(oRot, otempRot);        // get view direction        Vector3D oViewDir =             new Vector3D(oViewDirRot.A,                        oViewDirRot.B,                        oViewDirRot.C);        oViewDir.Normalize();        Debug.Print("View Direction: ",                     oViewDir.X,                    oViewDir.Y,                    oViewDir.Z);        // position        Point3D oPos = oCurVP.Position;        Debug.Print("Position: ",                    oPos.X,                    oPos.Y,                    oPos.Z);        // target        Point3D oTarget =             new Point3D(oPos.X + oViewDir.X * oFocal,                        oPos.Y + oViewDir.Y * oFocal,                        oPos.Z + oViewDir.Z * oFocal);        Debug.Print("Target: ",                        oTarget.X,                        oTarget.Y,                        oTarget.Z);             // rotation information        AxisAndAngleResult oAR =            oRot.ToAxisAndAngle();        Debug.Print("Rotation Axis: ",                     oAR.Axis.X,                    oAR.Axis.Y,                    oAR.Axis.Z);             Debug.Print("Rotation Angle: " +             oAR.Angle);                }

private Rotation3D MultiplyRotation3D(                Rotation3D r2,                 Rotation3D r1)    {                Rotation3D oRot =             new Rotation3D(r2.D * r1.A + r2.A * r1.D +                                r2.B * r1.C - r2.C * r1.B,                          
r2.D * r1.B + r2.B * r1.D +                                r2.C * r1.A - r2.A * r1.C,                           r2.D * r1.C + r2.C * r1.D +                              r2.A * r1.B - r2.B * r1.A,                           r2.D * r1.D - r2.A * r1.A -                               r2.B * r1.B - r2.C * r1.C);                  oRot.Normalize();        return oRot;    }

In the next article, we will introduce how to manipulate viewpoint.

(To be continued)