3D Sketch

3D Sketch is used to edit a family or create a 3D object. In the Revit Platform API, you can complete the 3D Sketch using the following classes.

• Extrusion
• Revolution
• Blend
• Sweep

In other words, there are four operations through which a 2D model turns into a 3D model. For more details about sketching in 2D, refer to 2D Sketch.

Extrusion

Revit uses extrusions to define 3D geometry for families. You create an extrusion by defining a 2D sketch on a plane; Revit then extrudes the sketch between a start and an end point.

Query the Extrusion Form object for a generic form to use in family modeling and massing. The Extrusion class has the following properties:

Table 40: Extrusion Properties

Property	Description
ExtrusionStart	Returns the Extrusion Start point. It is a Double type.
ExtrusionEnd	Returns the Extrusion End point. It is a Double type.
Sketch	Returns the Extrusion Sketch. It contains a sketch plane and some curves.

Figure 81: Extrusion result

Revolution

The Revolve command creates geometry that revolves around an axis. You can use the revolve command to create door knobs or other knobs on furniture, a dome roof, or columns.

Query the Revolution Form object for a generic form to use in family modeling and massing. The Revolution class has the following properties:

Table 41: Revolution Properties

Property	Description
Axis	Returns the Axis. It is a ModelLine object.
EndAngle	Returns the End Angle. It is a Double type.
Sketch	Returns the Extrusion Sketch. It contains a SketchPlane and some curves.

EndAngle is consistent with the same parameter in the Revit UI. The following pictures illustrate the Revolution corresponding parameter, the sketch, and the result.

Figure 82: Corresponding parameter

Figure 83: Revolution sketch

Figure 84: Revolution result

Note:

• The Start Angle is not accessible using the Revit Platform API.
• If the End Angle is positive, the Rotation direction is clockwise. If it is negative, the Rotation direction is counterclockwise

Blend

The Blend command blends two profiles together. For example, if you sketch a large rectangle and a smaller rectangle on top of it, Revit blends the two shapes together.

Query the Blend Form object for a generic form to use in family modeling and massing. The Blend class has the following properties:

Table 42: Blend Properties

Property	Description
BottomSketch	Returns the Bottom Sketch. It is a Sketch object.
TopSketch	Returns the Top Sketch Blend. It is a Sketch object.
FirstEnd	Returns the First End. It is a Double type.
SecondEnd	Returns the Second End. It is a Double type.

The FirstEnd and SecondEnd property values are consistent with the same parameters in the Revit UI. The following pictures illustrate the Blend corresponding parameters, the sketches, and the result.

Figure 85: Blend parameters in the UI

Figure 86: Blend top sketch and bottom sketch

Figure 87: Blend result

Sweep

The Sweep command sweeps one profile along a created 2D path or selected 3D path. The path may be an open or closed loop, but must pierce the profile plane.

Query the Sweep Form object for a generic form for use in family modeling and massing. The Sweep class has the following properties:

Table 43: Sweep Properties

Property	Description
Path3d	Returns the 3D Path Sketch. It is a Path3D object.
PathSketch	Returns the Plan Path Sketch. It is a Sketch object.
ProfileSketch	Returns the profile Sketch. It is a Sketch object.
EnableTrajSegmentation	Returns the Trajectory Segmentation state. It is a Boolean.
MaxSegmentAngle	Returns the Maximum Segment Angle. It is a Double type.

Creating a 2D Path is similar to other forms. The 3D Path is fetched by picking the created 3D curves.

Figure 88: Pick the Sweep 3D path

Note: The following information applies to Sweep:

• The Path3d property is available only when you use Pick Path to get the 3D path.
• PathSketch is available whether the path is 3D or 2D.

Figure 89: Sweep profile sketch

Note: The ProfileSketch is perpendicular to the path.

Segmented sweeps are useful for creating mechanical duct work elbows. Create a segmented sweep by setting two sweep parameters and sketching a path with arcs.

Figure 90: Corresponding segment settings in the UI

Note: The following information applies to segmented Sweeps:

• The parameters affect only arcs in the path.
• The minimum number of segments for a sweep is two.
• Change a segmented sweep to a non-segmented sweep by clearing the Trajectory Segmentation check box. The EnableTrajSegmentation property returns false.
• If the EnableTrajSegmentation property is false, the value of MaxSegmentAngle is the default 360°.

Figure 91: Sweep result