Bezier Creation Tool

Drawing Bezier Paths

EazyDraw uses the term "Bezier Path" to define a curve made from 3rd order Bezier curve segments joined at a sequence of vertices. For this style curve the slope (first derivative) of the curve may be discontinuous at the vertices. If you require continuous first derivatives at each vertex use the Smooth Bezier Curve tool.

You use the "Bezier Path Tool" (shown above) which is found on the Tools Palette to create Bezier paths. If the palette is not visible open it by selecting "Tools" from the "View" item of the "Main Menu". The new Bezier path will be drawn on EazyDraw’s front window. The desired window must be brought to the front before clicking on the tool.

Bezier Paths are drawn by clicking the "Bezier Path Tool Button" on the "Tools Palette". The "Tab Creation Cursor" (shown above) will reflect the tool selection when the mouse is over the front (top) document window. The Bezier path is drawn with the mouse. There are two ways to accomplish the drawing. You may use the "Tab Key" ("Enter Key" for left handed users) to advance to subsequent segments. The second process accepts a sequence of mouse clicks ending in a double click to define the Bezier path. Either method will work, no settings are required, EazyDraw recognizes your preference by your drawing actions.

The tab entry method defines the starting point of the Bezier path with the initial mouse down. Each subsequent vertex is defined by the mouse position when the tab key is pressed. The Bezier path is drawn by the process of drag - tab - drag - tab. The curve attempts to follow the actual motion of the mouse. You just trace out an approximation of the desired curve, dropping vertices with the Tab Key where needed. The final end point of the curve is defined when the process is completed by releasing the mouse. The "t" visual clue in the creation cursor is used because the "Tab Key" is used to add vertices to the Bezier path.

The second method starts the same way with a mouse down and subsequent drag operation to define the first Bezier path segment. Then subsequent vertices are defined by mouse clicks. Each click will cause a subsequent line segment to be added to the Bezier path. A straight portion of the segment is added from the previous vertex to the point of the mouse down click, then the curve attempts to follow the motion of the mouse. The process is completed by moving the mouse off the window or a double click. The double click does not add a final segment it just ends the operation.

Left handed users will find it easier to use the "Enter Key" instead of the "Tab Key". The first key (Tab or Enter) clicked is used for the rest of the Bezier path entry process (just the one).

It is not practical to draw a Bezier exactly as required during the creation step. EazyDraw allows convenient modification of the curve by manipulation of the vertices and Bezier Control points. A Bezier segment is defined by the two end points and two control points. The curve locus and slope transitions smoothly from the start to the end with the starting and ending slope determined by the line to the respective control point. Another way to visualize the control of the curve is to note that the slope at the midpoint of the curve is parallel to the line connecting the control points, and that the curve is pulled toward the control line. The control line is shown on the drawing when the Bezier curve is selected.

Vertices may be added using the Bezier Insert Tool or removed using the Knife Tool. While drawing the end segment may be removed with the Delete Key.

Another technique for creating curves is to start with a standard shape like an oval, polygon, or round rectangle. The starting shape is converted to a Bezier Curve. The convert action is found on the "Convert To" sub menu found on the "Tools" main menu. Then the starting shape can be modified or morphed into the desired shape by moving the vertices or controls.

If several Bezier paths are needed, double click the Bezier path tool. The Bezier path tool selection will remain in effect after creation so that further Bezier paths may be easily added to the document. Clicking another tool or the Arrow tool will release the Bezier path creation activity.

If Bezier paths are needed frequently, the Bezier path tool may be added to the Toolbar. If you prefer this convenience use the Customize Toolbar item found under "View" on the "Main Menu". There you will see the "Bezier Path Tool" button, just drag it to the position you prefer on the Toolbar.

After creating the Bezier path or curve the shape may be changed to a closed shape by double clicking either end of the curve. A closed path is drawn with a clean Join Style at the start/end vertex. If a shape is drawn by simply positioning the end of the curve at the point of the start of the curve, close inspection will show a rough joint that is actually defined by the Cap Style at the start-end vertex.