Aligning a 3D view to a specific orientation is incredibly useful during the design process. It provides better visual clarity and can help in understanding the spatial arrangement of elements. In Revit, this can be done through the user interface by right-clicking the view cube and selecting "Orient to View" or "Orient to Direction". But how can we achieve this programmatically using the Revit API? Let’s delve into this.

Understanding View3DOrientation

In the Revit API, the View3D class contains a crucial member called View3DOrientation. This class stores the directions of a view. Every view in Revit is defined by three vectors:

• Up Direction: Corresponds to the Y direction.

• Right Direction: Corresponds to the X direction.

• View Direction: Corresponds to the depth direction.

By retrieving these three vector values from one view and applying them to another 3D view, we can reorient the view to match the desired orientation.

Implementing the Orientation Change

Here’s a step-by-step guide on how to reorient a 3D view using the Revit API:

1. Retrieve the Target View: Obtain the target view from which you want to copy the orientation.

2. Get the Active 3D View: This is the view you want to reorient.

3. Create a ViewOrientation3D Object: This object will store the orientation of the target view.

4. Apply the Orientation: Use a transaction to apply the orientation to the active 3D view.

5. Update All Open Views: Refresh the views to reflect the changes.

Code Implementation

Below is a sample code implementation in C# that demonstrates how to reorient a 3D view in Revit:

View targetView = Doc.GetElement(new ElementId(29154)) as View;
View3D v3d = UiDoc.ActiveGraphicalView as View3D;
var ori = new ViewOrientation3D(
    targetView.Origin,
    targetView.UpDirection,
    targetView.ViewDirection
);
using (var trans = new Transaction(Doc, "Orient View"))
{
    trans.Start();
    v3d.SetOrientation(ori);
    trans.Commit();
}
UiDoc.UpdateAllOpenViews();

Aligning to an Element Face

In addition to aligning a 3D view to another view, you can also align a 3D view to any element face. To do this, you need to extract the necessary directional values from the face of the element:

• Right Direction: The X vector of the face.

• Up Direction: The Y vector of the face.

• View Direction: The normal vector of the face.

Here’s how you can achieve this:

1. Retrieve the Face: Get the face of the element you want to align to.

2. Extract Directional Values: Get the right, up, and view directions from the face.

3. Create a ViewOrientation3D Object: Use these values to create the orientation object.

4. Apply the Orientation: Set the orientation of the 3D view.

Code Implementation for Element Face Alignment

// Assuming 'face' is an instance of Autodesk.Revit.DB.Face
XYZ upDirection = face.YVector;
XYZ viewDirection = face.FaceNormal;

// Assuming 'origin' is a point on the face
XYZ origin = face.Evaluate(new UV(0.5, 0.5)); // Midpoint of the face as origin

var ori = new ViewOrientation3D(origin, upDirection, viewDirection);

using (var trans = new Transaction(Doc, "Align to Face"))
{
    trans.Start();
    v3d.SetOrientation(ori);
    trans.Commit();
}

UiDoc.UpdateAllOpenViews();

Explanation

• Retrieve Target View: View targetView = Doc.GetElement(new ElementId(29154)) as View;

  • This line retrieves the view with the specified ElementId. Replace 29154 with the actual ElementId of your target view.

• Get Active 3D View: View3D v3d = UiDoc.ActiveGraphicalView as View3D;

  • This line retrieves the currently active 3D view.

• Create ViewOrientation3D Object: var ori = new ViewOrientation3D(targetView.Origin, targetView.UpDirection, targetView.ViewDirection);

  • This line creates a ViewOrientation3D object using the origin, up direction, and view direction of the target view.

• Transaction to Apply Orientation:

    using (var trans = new Transaction(Doc, "Orient View"))
    {
        trans.Start();
        v3d.SetOrientation(ori);
        trans.Commit();
    }
  

  • This block of code starts a transaction, sets the orientation of the active 3D view to match the target view, and then commits the transaction.

• Update Views: UiDoc.UpdateAllOpenViews();

  • This line refreshes all open views to reflect the changes.

Conclusion

Aligning 3D views to a specific orientation or matching another view can significantly enhance your workflow in Revit. By utilizing the View3DOrientation class in the Revit API, you can programmatically achieve precise view alignments, facilitating a more efficient and visually clear design process. This approach is not only powerful but also relatively straightforward to implement. Additionally, aligning a 3D view to an element face by extracting the face’s directional values provides even greater flexibility and precision in viewing specific parts of your model.