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The Bezier tool allows you to create a type of curve defined by off-curve control handles. A Bezier curve is a type of curve defined by additional off-curve control handles and were originally developed for computer modeling in automotive design, but are popular in many vector drawing applications. These curves provide a more familiar means of generating curves, as they allow you to interactively control the amount of incoming and outgoing curvature for each control point.
The Bezier tool is found in the Basic sub-tab of the modeling toolbox. Right-click to open the button pop-up menu to find it (by default, it is located under the Pen tool button). Alternatively, you can also access it by opening the Curve palette, found in the menu bar under Geometry > Curve Palette. Click the button to activate the tool.
In the 3D Viewport, click to position the first control point and then continue to drag the mouse cursor to create the Bezier handle. Releasing the mouse button sets the handle length. Subsequent clicking and dragging draws additional control points and handles with a curve segment drawn between each vertex. Control points are always created at the intersection of the work plane and the mouse button click. The curvature of the segments between control points is defined by the Bezier handles (called endpoint tangent vectors).
While the tool is active, you can hover over any of the control points (changing them from blue to yellow), clicking and dragging to reposition it. Points always move on the two axes relative to the current work plane, so rotating the viewport to change an axis may be necessary. Handles are edited in the same manner. Pressing and holding the Ctrl key when editing handles breaks tangency, allowing opposing handles to be different lengths and/or angles. Editing any handle without pressing Ctrl restores tangency. When editing (moving) control points, pressing and holding Shift moves all downstream control points as a single unit.
There are three edit modes: Add to add additional control points after the most recently-selected control point, Edit to change a control points location, and Delete to remove any control point that is clicked. Once the tool is dropped (by pressing the Q key), interactive handle editing within the tool itself is lost but you can re-activate the editing ability by first selecting the curve itself in Polygons component selection mode, before activating the tool again. Clicking in the viewport again displays the editing handles. Control points along the Bezier curve can also be positioned precisely by selecting the target vertex and using the Point X, Y, Z fields of the tool's Properties panel.
The following Bezier options are available for adjusting the Bezier tool:
• Mode - there are several Bezier curve mode options:
• Add - the default mode; when you click in the viewport, additional points are added to the curve. At each control point position, two handles extend out that allows you to adjust the curvature of the curve segment between vertices. While drawing, you can hover over any point or handle where it turns yellow. You can then click-and-drag the control point or handle to further edit the curve. Control points may be added mid-curve by selecting the preceding control, highlighting it yellow, and clicking the position where the new control point is desired (point order is defined by the initial order in which the curve was created. Press F prior to activating the tool to invert the order.).
• Edit - freely click-and-drag any of the control points or handles along the curve to change the look to the desired shape. While pressing the Ctrl key, you can break the tangency of the control handles, allowing for sharp corners.
• Delete - click on any control point along the curve to remove it from the Bezier.
• Point X, Y, Z - if you want finer point control, you can assign specific XYZ values in these input fields for the currently selected (highlighted) control point.
• In X, Y, Z/Out X, Y, Z - if you want finer handle control, you can assign specific XYZ values in these In and Out input fields for the currently-selected (highlighted) control point.
• Closed - adds an automatic curve segment between the first and last control point positions, producing a closed curve.
• Filled - when the Closed option is enabled, you can additionally enable the Filled option to create a render-able flat surface that is defined by the outlining curve itself. The resulting surface can be tagged like a polygon for adding material definitions.
• Make UVs - activates auto-generation of UV texture coordinates along the curve. The generated UV values are of a single vertical line ('V' axis in UV), positioning all the control point vertices evenly between 0 and 1. For example, this can be useful for applying a gradient to a rendered curve (the Render Curves option is available in the Mesh Item properties.