Overview

1. The line and circle objects so far created were drawn at random on the screen without any attempt being made to specify position or size.

2. To draw objects accurately, co-ordinate input is required and AutoCAD 2006 allows different 'types' of co-ordinate entry including:

   1. Absolute, i.e. from an origin point

   2. Relative (or incremental), i.e. from the last point referenced.

3. In this chapter we will use our A3PAPER template file to create a working drawing and use it for future work.

Conventions

When using co-ordinate input, the user must know the positive and negative directions for both linear and angular input. The two conventions are as follows:

1. Co-ordinate axes

   The X Y axes convention used by AutoCAD is shown in Figure 7.1(a) and displays four points with their co-ordinate values. When using the normal X Y co-ordinate system:

   
   Figure 7.1: Co-ordinate and angle conventions.

   1. a positive X direction is to the right, and a positive Y direction is upwards

   2. a negative X direction is to the left, and a negative Y direction is downwards.

2. Angles

   When angles are being used:

   1. positive angles are anti-clockwise

   2. negative angles are clockwise

   3. Figure 7.1(b) displays the angle convention of four points with their polar co-ordinate values.

Getting started

1. If your template file from Chapter 6 is displayed, proceed to step 4.

2. 1. If AutoCAD is active, then close any existing drawing then menu bar with File-Open and:

      prompt	Select File dialogue box
      respond	file type: scroll and pick Drawing Template (*.dwt)