What is a Taper Object for Curves in Blender?

In Blender, a taper object is a secondary curve used to dynamically control the thickness or scale of a primary curve along its entire length. By assigning a open or closed curve as a taper object, Blender maps the vertical height and shape of the taper curve to the thickness of the main curve, allowing for precise, non-destructive control over form and silhouette. This technique is widely used for modeling organic shapes like tentacles, horns, plant stems, and stylized hair strands without manually adjusting individual vertex radii.

How a Taper Object Works

When you assign a taper object to a curve, Blender evaluates the taper curve along its local horizontal (X) axis and translates its vertical (Y) distance from its origin into scaling factors for the target curve.

  • The X-Axis Represents Length: The starting point of the taper curve's X-axis corresponds to the beginning of the main curve, while the end of the X-axis corresponds to the tip of the main curve.
  • The Y-Axis Represents Thickness: The height of the taper curve above or below its local X-axis determines how thick or thin the main curve becomes at that relative point.

If the taper curve lies flat on its X-axis, the main curve will have zero thickness. Elevating points on the taper curve increases the main curve's radius proportionally.

Step-by-Step Implementation

  1. Create the Main Curve: Add a Bézier or Path curve to your scene and give it geometry by increasing the Depth value under the Geometry > Bevel section in the Curve Properties panel.
  2. Create the Taper Curve: Add a second curve (such as a separate Bézier curve) that will serve as the controller.
  3. Assign the Taper Object: Select the main curve, navigate to the Data Properties tab, expand the Geometry rollout, locate the Taper Object field, and select your second curve.
  4. Adjust the Shape: Select the taper curve, enter Edit Mode, and move its control points vertically to alter the thickness profile of your main curve in real time.

Important Considerations

  • Origin Location: The origin point of the taper object acts as the zero-baseline for thickness. Keep the origin aligned properly to avoid unexpected flattening or swelling.
  • Non-Destructive Workflow: Because the taper relationship is non-destructive, you can modify either curve at any point during your modeling process, or swap out different taper objects to test different shapes instantly.
  • Convert to Mesh: Once you are satisfied with the tapered shape, you can convert the main curve into a polygonal mesh by right-clicking it in the viewport and selecting Convert To > Mesh.