Straight Construction Line Parallel to Other Line, Tangent to Curve

1. Call the Line command.

2. Select a straight line for the new line to be parallel to. You can select a construction line or a graphic one. A line can be selected in one of the following ways:

•Move the cursor over the desired line, using object snappings, and press or <Enter>. In case of selecting a graphic line, a coinciding straight construction line is created automatically, and the current line is based on such construction line.

•Use the following automenu option:

This option is active by default, upon calling the command, so in order to select a construction line nearest to the cursor, you just have to click within drawing window or press <L> or <Enter>.

Upon selection, the preview of the resulting line follows the cursor.

After selecting a line, you can create axes of symmetry, if necessary, and then continue the parallel line creation.

3. Select a curve for the new line to be tangent to. You can select a construction line (circle, ellipse, 2D path, spline, offset curve, function spline) or a graphic line (circle, circular arc, ellipse, elliptic arc). The configuration of tangency between the selected curve and the resulting line depends on the position of the cursor at the moment of selection: a tangency point will be located as close as possible to the normal projection of the cursor position onto the curve. A curve can be selected in one of the following ways:

•Move the cursor over the desired line, using object snappings, and press or <Enter>. In case of selecting a graphic line, a coinciding construction line (circle or ellipse) is created automatically, and the current line is based on such construction line.

•Activate one of the following automenu options:

If the option is activated via keyboard, then the construction line of the corresponding type nearest to cursor gets selected instantly.
If the option is activated via mouse, then you have to additionally press within drawing window for selecting the nearest line.
In addition to splines, the spline selection option allows selecting 2D paths, offset curves and function splines.

Example of creating a parallel line tangent to ellipse

Example of creating a parallel line based on the same elements with different tangency configuration

 

The relation mark connects the resulting line with the initial one and indicates their parallelism. The mark at the tangency point indicates tangency.

After creating a line, the command stays in the mode of creating lines parallel to the same selected line. In order to return to the initial state of the command, press or <Esc>, or use the following automenu option: