Basic Shapes in Drawn Rectangle

Basic shapes create basic objects that can be modified later as desired. They are located within the dashed rectangle drawn with the mouse.

Lines

This basic shape consists of two straight lines and is defined by three points. You can also delete one point to create a single line or add additional points to create a chain of many lines.

Curves

This basic shape consists of two curves and is defined by three main points with two control points per curve. You can also delete a main point to create a single curve or add additional points to create a chain of many curves.

Only the main points are given point numbers. The control points are named with the number of the associated main point and +/-. "+" for a control point behind a main point and "-" for a control point in front of a main point. The first and last main point only have a single control point.

This method of defining a curve using main and control points was developed by the French engineer Pierre Étienne Bézier (1910-1999), which is why these curves are called "Bézier" curves. The control points determine the path of the curves. The line between the main point and the control point serves as the tangent of the curve at the main point, which is the direction of the curve at the main point. The distance between the main point and the control point determines the "pull" of the tangent. The smaller this distance is, the more quickly the curve diverges from the tangent.

If you want two curves to converge at a main point without a kink, the main point and the two adjacent control points must all be positioned in a straight line. This will ensure that both curves have the same tangent at the common main point. This is the case for the central main point in the sample basic shape.

Rectangle

This basic shape takes on the form of the rectangle drawn by the mouse, which is only defined by two points. The surface area of the shape can be filled with color.

When dragging one of the points with the mouse, you can create a square by holding the Ctrl key.

Rounded rectangle

This basic shape takes on the form of the rectangle drawn by the mouse and rounds the corners. The radius of the rounded corners can be set in mm or inch. The surface area of the shape can be filled with color.

When dragging one of the points with the mouse, you can create a square by holding the Ctrl key.

Polygon

This basic shape is a triangular polygon that is defined by three points. You can add additional points to a polygon to create shapes with many corners. The surface area of the shape can be filled with color.

Ellipse

This basic shape creates an ellipse in the rectangle drawn with the mouse. The ellipse is defined by only two points. The surface area of the shape can be filled with color.

When dragging one of the points with the mouse, you can create a circle by holding the Ctrl key.

Closed Curves

This basic shape consists of eight curves and is defined by nine main points with two control points per curve. You can delete or add main points to modify the shape.

If the first and the last main point lie exactly over each other (like in the illustration shown above, red circle), they can not be seen in the marked object; the points are drawn by reversal of the color value and the double reversal does not lead to any visible change. However, you can follow the line with the mouse and see at the change of the cursor where such a pair of hidden points is. In addition, you can edit the coordinates in the table in the Edit Free Geo Objects dialog.

If the first and the last main point lie not exactly over each other, they will be connected by a straight line closing the shape.

This method of defining a curve using main and control points was already described for curves above.