Tutorial 3 - Geometry

Geometry is represented by construction lines and circles which can be used as guidelines for:

Tracing over.
Determining the positions of points.
Determining line and arc intersection points.
Projecting existing lines to another part of the drawing.

The following geometric constructions are available.

Icon	Description
	Intersecting horizontal and vertical geometry lines (cross).
	Line at a defined angle.
	Line through two points.
	Line tangent to a circle.
	Line tangent to two circles.
	Circle.
	Up to five concentric circles.
	Circle through 3 points.
	Circle tangent to a line.
	Circle tangent to two lines.
	Circle tangent to three lines.
	Circle tangent to a line and a circle.
	Circle tangent to a circle.
	Circle tangent to two circles.
	Line parallel to an existing line or circle.
	Line that is a perpendicular bisector of two points or a line.
	Divide a circle into an equal number of segments.

Properties of Geometry

Geometry has the following properties:

It has no end points and continues into infinity.
It is not printed or plotted.
It is common to all layers.
Geometry is automatically stored when you save a drawing.

Using Geometry as Guidelines to Trace Over

To use geometry as guidelines to trace over, you must first draw the geometry using the options above.

You can trace over it by selecting Draw ► Geometry Trace Over. The most useful of these functions is Fill Geom, which allows you to trace over geometry lines and circles by specifying intersections and the geometry lines and circles connecting them.

For example, if this is the geometry you have created, you might specify an intersection.

Now specify a line between intersections.

Specify another intersection. The line is automatically drawn as a solid line. You can also draw over arcs in this way.

Projecting Solid Lines and Arcs to Geometry Lines and Circles

The Geometry ► Make Geometry function projects solid lines and arcs into geometry lines and arcs. This is useful for projecting lines into another part of the drawing, or for finding the intersection point between projected lines and arcs.

Jumping to Geometry Lines, Arcs and Intersections

The following Jumps will jump to Geometry. These can be found in Tools ► Jumps.

Jump	Icon	Key	Function
Geom Intersection		[I]	Jump to geometry intersections and tangency points.
Any Intersection		[0] (Zero)	Jump to intersections between geometry and solid lines and arcs.
Nearest Entity		[N]	Jump to the nearest line or arc, be it solid or geometry.

Snapping to Geometry Lines, Arcs and Intersections

The following Snap modes will snap to Geometry.

Snap	Icon	Key	Function
Grab All		[Shift+A]	Snaps to a geometry intersection, tangency point, or intersection between geometry and solid lines and arcs, if this is within specified snap distance.
Geometry Intersection		[Shift+I]	Snaps to a geometry intersection or tangency point.
Intersection		[Shift+Z]	Snaps to intersections between geometry and solid lines and arcs.
Nearest Entity		[Shift+N]	Snaps to the nearest line or arc, solid or geometry.
Perpendicular		[Shift+P]	Snaps lines, including geometry lines, to other lines or arcs so that they are perpendicular to each other. This mode only works when you are drawing lines, including polylines and geometry point to point lines.

For example, if you have selected the Geometry ► Lines ► Point-to-Point Line function, you are prompted to:

Indicate start position of line

Position the cursor at a point the geometry line must pass through, and then click or press [Enter].

You are prompted to:

Indicate end position of line

Enter Perpendicular snap mode by clicking the Perp snap icon. The cursor changes shape.
Position the cursor close to the line that the geometry line you are drawing must be perpendicular to, and then click or press [Enter].

The geometry line is drawn perpendicular to the other line.

Tan Mode

Snaps lines and arcs, including geometry lines and circles, to other lines or arcs so that they are tangential to each other.

Click the Tan snap icon or type press [Ctrl+T] as a shortcut. Tan snap only works when you are drawing lines or arcs, including polylines and geometry lines and circles.

For example, if you have selected the Geometry ► Lines ► Point-to-Point Line function, you are prompted to:

Indicate start position of line

Position the cursor at a point the geometry line must pass through, and then click or press [Enter].

You are prompted to:

Indicate end position of line

Enter Tan mode by clicking the Tan Snap icon, or pressing [Ctrl+T] as a shortcut to this mode. The cursor changes shape.
Position the cursor close to the arc that the geometry line you are drawing must be tangential to, and then click or press [Enter].

The geometry line is drawn tangential to the arc.

Switching Geometry On and Off

If you no longer need your geometry, you can delete it or switch it off.

To switch the geometry off:

Select Geometry ► Switch Geometry On/Off. The following message briefly displays in the prompt area:

Geometry display is now OFF

The geometry disappears from view, although it is still there. Even though you can’t see the geometry you are still be able to jump to it (see Jumping and Snapping above). You can switch it on again at any time by selecting Geometry ► Switch Geometry On/Off again. The following message displays briefly in the prompt area:

Geometry display is now on

Deleting Geometry

To delete a single geometry line or circle, select Geometry ► Delete Geometry Entity.

To delete all your geometry, select Geometry ► Delete All Geometry.

Geometry deletion is permanent. The Undo function does not restore a deleted geometry element.