Using Cartesian coordinates

Many commands in CAD.direct require that you specify points as you draw

or modify entities. You can do so by selecting points with the mouse or by typing

coordinate values in the command bar. The program locates points in a drawing

using a Cartesian coordinate system.

Understanding how coordinate systems work

The Cartesian coordinate system uses three perpendicular axes — x, y, and z — to

specify points in three-dimensional space. Every location in a drawing can be represented as a point relative to a 0,0,0 coordinate point, referred to as the origin. To draw a two-dimensional entity, you specify horizontal coordinate positions along the x-axis and vertical coordinate positions along the y-axis. Thus, every point on a plane can be represented as a coordinate pair composed of an x-coordinate and a y-coordinate.

Positive coordinates are located above and to the right of the origin; negative coordinates

are located to the left and below the origin.

When you work in two dimensions, you need enter only the x- and y-coordinates; the

program assumes that the z-axis value is always the current elevation. When you

work in three dimensions, however, you must also specify the z-axis value. When you

look at a plan view of your drawing (a view from above, looking down), the z-axis

extends straight up out of the screen at a 90-degree angle to the xy plane. Positive

coordinates are located above the xy plane, and negative coordinates are below the

plane.

All CAD.direct 2019 drawings use a fixed coordinate system, called the World Coordinate System (WCS), and every point in a drawing has a specific x,y,z coordinate

in the WCS. You can also define arbitrary coordinate systems located anywhere in three-dimensional space. These are called user coordinate systems and can be located any-where in the WCS and oriented in any direction.

You can create as many user coordinate systems as you want, saving or redefining them to help you construct three-dimensional entities. By defining a UCS within the WCS, you can simplify the creation of most three-dimensional entities into combinations

of two-dimensional entities.

To help you keep your bearings in the current coordinate system, the program displays

a coordinate system icon. When you begin a new drawing, you are automatically in the WCS, indicated by the letter W in the icon. When you display a drawing in plan view, you see the coordinate system icon from the top, with the z-axis directed straight toward you. When you display a three-dimensional drawing in a view other than plan view, the coordinate system icon changes to reflect your new viewpoint.

The visible portions of the axes are the positive directions.

The invisible portions are the negative directions.

The CAD.direct UCS icon looks different from the UCS icon in AutoCAD, because it presents more information. Three colors represent the three axes, making it easier for you to recognize the orientation in three-dimensional space:

• x-axis: red

• y-axis: green

• z-axis: blue

If you prefer a single color for the cursor and UCS icon, you can make that change with the config or options command.

Understanding how coordinates display

The current position of the cursor is displayed as x,y,z-coordinates in the status bar and, by default, updates dynamically as you move the cursor. You can toggle the coordinate display to static mode by pressing F6, so that it updates only when you select a point in the drawing.

You can also change the coordinate display to a different dynamic mode that shows the distance and angle (rather than x,y,z-coordinates) when the program displays a rubber-band line. To do this, choose Tools > Drawing Settings and select the Display tab. Under Coordinate Display, select the option for Coordinates In Polar Form For Distance And Angle Selection.

Finding the coordinates of a point

To find the x,y,z-coordinates for a point on an entity, such as the endpoint of a line, select an appropriate entity snap (such as Endpoint) before selecting the entity. If you have no entity snaps set, the x,y-coordinates of the point you specified is displayed, with the z-coordinate equal to the current elevation.