Because CAD software has the ability to snap to any of the 'geometric' points on an element in the drawing (entity snaps) it is possible make a new entity jump (or lock onto) to a defined point on an existing entity using what is called an entity snap. The following entity snap jump points are available:
Center, Near, End, Mid, Node Quadrant (Grip), Tangent, Perpendicular, Near, InsertionPoint, SnapPoint (Node), Intersection
Every entity placed in a drawing has a number of defined snap points. These are indicated by so-called 'handles' or ''grips'. An example is shown below. Many of the entities you use in a gCADPlus drawing are shown together with the handles on each.
Tip: Every entity has handles, even text entities. The figure below shows some selected entities with their grips.
Beginner CAD drafters often position new entities in drawings by eye - near enough is seen to be good enough; as long as a drawing plots correctly, that will do. We frown on that approach and want you to learn to use the existing geometry in the drawing when placing entities. Sensible CAD users always make the software work hard for them, not the other way round.
These geometric points are available at any time when you are asked to nominate a 'To point' at any point in an command your drafting, it is possible to nominate one of these key geometric points an lock onto one. Once the type of snap is set, the CAD software will then find the point for you.
Tip: If you do not understand how to control these properly, the response of gCADPlus may slow considerably, or worse still, new entities may be placed in unintended positions because the software is 'snapping' to unexpected places.
In short, it is best to let the CAD software locate entities in drawings via entity snaps rather than rely on placing things 'by eye'.
One-shot vs. "running" osnaps
You can work with entity snaps in one of two ways:
Enable a one-time entity snap for a single selection by choosing an entity snap when a command is active.
Enable a running entity snap that remains in effect until you turn it off by choosing an entity snap when no other command is active.
Tip: When using entity snaps, gCADPlus recognizes only visible entities or visible portions of entities. You cannot snap to entities on layers that have been turned off or to the blank portions of dashed lines.You can also use a one-time entity snap to override a running entity snap.
When you specify one or more entity snaps, an entity snap target box is added to the cross hairs. In addition, an icon appears adjacent to the cross hair indicating the active entity snap. When you select an entity, the program snaps to the snap point closest to the center of the target box.
The program provides visual indicators to show that an entity snap is turned on. When any entity snap is turned on, OSNAP changes color on the status line.
The OSNAP command - running entity snap
This command enables you to set a running entity snap which remains in effect until you turn it off.
Tip: it is not a good idea to draft with all entity snaps turned on as shown here - one ot two should be enough.
A quick example
So entity snaps enable you to quickly select exact geometric points on existing entities without having to know the exact coordinates of those points. With entity snaps, you can select (say) the end point of a line or arc, the center point of a circle, the intersection of any two entities, or any other geometrically significant position whenever the software asks for a point location. The location does not even have to be an entity. You can use entity snaps to draw entities that are tangent or perpendicular to an existing entity.
Tips: When using entity snaps, the program recognizes only visible entities or visible portions of entities. You cannot snap to entities on layers that have been turned off or to the blank portions of dashed lines.
When you specify one or more entity snaps, an entity snap target box is added to the cross-hairs. In addition, an icon appears adjacent to the cross-hair indicating the active entity snap. When you select an entity, the program snaps to the snap point closest to the center of the target box.
The flyover cursor can also operate and provide an appropriate marker when the geometric point has been found. Different markers are displayed for each type of entity snap.
This entity snap option can be used to good effect. It enables entities such as plant symbols to be located on an arc with spacing set by eye.