This is a portion of our DraftSight User Manual, which should be accessible via the EagleRock Help icon on your machine's Desktop.  If you do not have a Help icon, contact EagleRock customer support to have this feature added.


Coordinates

In nearly all of your interactions with the drawing area you will be entering coordinates to define points. For example, to draw a line you will specify the coordinates of the line’s start point and end point; to draw a circle you will specify the coordinates of the circle’s center and radius.


With DraftSight’s ample tools, you will not need to rely solely on entering coordinates manually, but will be able to use the mouse for much of your drawing.

 

DraftSight works with two formats when entering fractions. You can use a decimal: 1.75; or you can use a fraction 1-3/4. When entering fractions, be sure to separate the integer and the numerator with a - (dash), not a space.


DraftSight accepts the input of two different coordinate systems, the Cartesian coordinate system and the polar coordinate system. Within those two systems, coordinates can be entered either as absolute coordinates or as relative coordinates.


Cartesian Coordinate System

The Cartesian coordinate system defines points by their position on the X and Y axes:



The Cartesian Coordinate System

source: Wikipedia.org


Most likely you are already familiar with the Cartesian coordinate system. The origin of this system is the intersection of the X and Y axes. Y increases as you move up and decreases as you move down. X increases as you move right and decreases as you move left.


Polar Coordinate System

The polar coordinate system uses a less familiar method in designating points. This system defines points by a distance and an angle. The distance refers to the distance from the origin and the angle refers to the angle from a line that starts in the origin and goes right (see figure below). The angle increases as it moves counter clockwise around the origin:


The Polar Grid

On the grid are 3 three points:

  • The red point is 3 units from the origin at a 45° angle.

  • The green dot is 3 units from the origin at a 180° angle.

  • The blue dot is 1 unit from the origin at a 337.5° angle.


Absolute vs Relative

DraftSight accepts the input of both absolute and relative coordinates. The distinction between absolute and relative coordinates may be a new concept.


To explain this concept, I will use the pages in this manual as an example. Let’s say that I want you to read pages 9, 10, 11 & 12 of this manual. There are two ways I might ask you do this:


  • Read pages 9 to 12.

  • Start on page 9 and read 4 pages.


In the first example, I referred to the pages as numbered from the first page. This is analogous to using absolute coordinates. Both of my page numbers were in relation to page 1, a page number which is fixed, or absolute.


In the second example, I told you to start on page 9 and from that point, read 4 pages. This is analogous to using relative coordinates. When I asked you to “read 4 pages”, I was using page 9 as a starting point. In this sense, the 4 pages are relative to the starting point of page 9.


Let’s look at another example. Below is a drawing of two lines, one line extending from points A to B and the other line extending from B to C:



If we were tell someone how to draw these lines, we would likely tell them to first draw a 5 unit line, and then, from the end point of the first line, draw a 7 unit line.


In doing so, we would have given the second line using relative coordinates, because the start point of the second line was drawn in relation to the end point of the first line. Our origin (the 0 point) changed places while we were drawing. We drew from 0 to 5 to draw the first line, and then started at 0 once again, measuring out 7 units to draw the second line.


With relative coordinates, the origin is relative to the last point you entered.


On the other hand, if we were to use absolute coordinates to explain the diagram above, we would say to draw a line from 0 to 5, and another line from 5 to 12. This is because we would measure out from 0 (point A) for every measurement.


In general, the measurements you use to create drawings will be relative to other measurements, not a single fixed point.


Absolute Coordinates

By default, when you specify coordinates in DraftSight they are interpreted as absolute coordinates, meaning that they are they are relative only to the the origin of the drawing. The drawing’s origin is in a fixed (absolute) location and never moves. The origin’s location is represented by this symbol:



Absolute coordinates are not something that are normally relied on in granite fabrication. However, it is important to understand how they work.


Absolute Cartesian

DraftSight’s syntax for absolute cartesian coordinates is: X,Y with no spaces.


source: Wikipedia.org

For example, in the diagram above the coordinates of the blue dot are -1.5,-2.5, and the green dot’s are 2,3


If we wanted to draw a line from the blue dot to the green dot, we would specify -1.5,-2.5 as the start point and 2,3 as the end point.


Absolute Polar

Draftsight’s syntax for absolute polar coordinates is: length<angle with no spaces.



For example, in the diagram above, the coordinates of the red dot are 3<45 and the blue dot are 1<337.5. If we wanted to draw a line from the red dot to the blue dot, we would specify 3<45 as the start point and 1<337.5 as the end point.


Relative Coordinates

As we discussed earlier, when drawing with relative coordinates, the origin is the last point that was drawn. Since relative coordinates depend on a previous point, they can not be used to start an entity. The first point needs to be entered using absolute coordinates; once the first point has been entered, a point relative to it can be drawn. Relative coordinates are designated by an ampersand, or “at sign”.


Relative Cartesian Coordinates

The syntax for relative Cartesian coordinates is @X,Y with no spaces.


source: Wikipedia.org


For example, in the diagram above, to draw a line from the red dot to the origin (0,0), we would start the line using absolute coordinates, -3,1, then we would specify relative Cartesian coordinates: @3,-1 DraftSight will then count 3 to the right and one down from the red dot, and draw a line to origin.


If we wanted to draw a rectangle 55 units wide and 26 units tall, we could specify our start point with the mouse on a random part of the drawing area, and then enter @55,26 as the opposite corner.


Relative Polar Coordinates

The syntax for drawing relative Cartesian coordinates is @distance<angle.


For example, in the diagram above, to draw a line that starts at the blue dot and follows the dashed line straight up to the X axis, we would first start our line at -1.5,2-2.5 and then enter @2.5<90. This will draw a line of 2.5 units at a 90° angle. Similarly, starting a line at 2,3 and entering @3<270 will draw a line from the green dot to the X axis.