Drawing elliptical arcs by center and radii

You can construct an elliptical arc by drawing its "parent" ellipse by center and radii first: the ellipse is defined by its center (the first point you draw) and its primary and secondary radii. The ellipse is positioned according to the angle between the primary radius and the x-axis.

When the "parent" ellipse has been constructed, the elliptical arc is defined by the starting and end points of the elliptical arc curve — they could lie anywhere on the circumference of the "parent" ellipse that the arc belongs to. The starting and end points are defined by the angles formed by the two respective radii (connecting the starting and end points with the center) against the x-axis.

The contextual edit bar

During drawing and when selected.

For help on snapping, see Snapping objects.

Starts the Detect Relations Manager.

The appearance of the contextual edit bar may differ depending on the relations you have set.

Relative Dx and Dy while repositioning the elliptical arc.

Attributes

• Primary radius. Displayed as Primary in the contextual edit bar, and as r1 =... in the Data column in the tabular area.
• Secondary radius. Displayed as Secondary in the contextual edit bar, and as r2 =... in the Data column in the tabular area.
• Angle. The angle between the primary radius and the x-axis. Displayed as Angle in the contextual edit bar. Learn how to use the automatic computation of angles .
• Start angle. The angle between the x-axis and the radius that connects the center of the parent ellipse with the starting point of the elliptical arc. Displayed as Start in the contextual edit bar.
• End angle. The angle between the x-axis and the radius that connects the center of the parent ellipse with the end point of the elliptical arc. Displayed as End in the contextual edit bar.
• Circumference length. Displayed in the Length column in the tabular area.
• Relative Dx and Dy. These attributes are displayed on the contextual edit bar only during repositioning of an elliptical arc by dragging. Dx and Dy are the relative horizontal and vertical offset distances between the original and the repositioned elliptical arc locations as projected on the coordinate axes. The Dx/Dy values are, respectively, the Ox/Oy coordinate position of the repositioned elliptical arc less the proportional Ox/Oy coordinate position of the original elliptical arc.
• Style. Learn about how to format styles.
• Id. A unique, system-generated object identification number. Appears in the Id column in the tabular area.

Control points

An elliptical arc constructed by center and radii has five control points: the center and the end points of the primary and secondary radii of the "parent" ellipse, and the starting and end points of the elliptical arc. While you are drawing an elliptical arc by center and radii, the following mouse pointers appear:

About to mark the center of the "parent" ellipse.

About to mark the end point of the primary radius of the "parent" ellipse.

About to mark the end point of the secondary radius of the "parent" ellipse.

About to mark the end point of the elliptical arc.

Tabular presentation

When you have finished drawing an ellipse, its object type, Id number, circumferential length, primary and secondary radii of the "parent" ellipse, and style are recorded in the Objects tab in the tabular area.

NOTE: The data in the Objects tab is unavailable for direct editing.

To draw an elliptical arc by center and radii

1. Do any of the following:

• On the Objects toolbar, click Elliptical Arc by Center and Radii .
• On the Objects menu, point to Elliptical Arcs, and then click Elliptical Arc by Center and Radii.
• Press CTRL+D+E+A+C.

2. (Optional) Snap the center point of the "parent" ellipse that you are about to place, to another object or point.
3. In the graphical pane, click to draw the center point of the "parent" ellipse.
4. (Optional) Snap the end point of the primary radius of the "parent" ellipse that you are about to place to another object or point.
5. Define the primary radius of the "parent" ellipse by doing one of the following:

• Drag the mouse to where you want the end point of the primary radius to be.
• In the contextual edit bar, in Primary and Angle, enter respective values.
• Snap the end point of the secondary radius of the "parent" ellipse that you are about to place to another object or point.

6. Define the secondary radius of the "parent" ellipse by doing one of the following:

• Point in one of the two possible directions left and draw the end point of the secondary radius.
• In the contextual edit bar, in Secondary enter a respective value, and then click.

7. Define the starting and end points of the elliptical arc by doing one of the following:

• Move the mouse pointer clockwise along the ellipse circumference, and click where you want the two points to be.
• In the contextual edit bar, in Start and End enter values, and then click.
• Snap the points to other objects or points.

To modify an elliptical arc by changing its attributes

1. Select the elliptical arc.
2. In the contextual edit bar, enter attribute values, and then press ENTER.

To reposition an elliptical arc by dragging

1. Select the elliptical arc.
2. Do any of the following:

• Drag the elliptical arc to where you want it to be.
• In the contextual edit bar, in Dx and Dy enter offset distances relative to the original location of the elliptical arc.

3. Click to position the arc.

NOTE: If the control points of the elliptical arc coincide with the control points of another objects — for example, when the elliptical arc is part of a box or is connected to another object by its circumferential control points — EngView repositions the elliptical arc and modifies the connected objects depending on the direction and distance at which you drag the arc.