Page 104 - Engineering drawing from first principles using AutoCAD

Pictorial projections 97

reproduce the curves on the rear face. Two typical construction points for the top curve
are illustrated.

Simple animation

The COpy and ROTATE features can be used to demonstrate a simple form of animation.
Design a bird that you fancy of reasonable size with the CIRCLE and LINE commands.
Enlarge the eyeball and beak with the ZOOM command before filling these small areas
with a few polyline strokes. Add centre lines where the head, wings and legs are required
to rotate.
Using the COpy command, draw boxes in turn, just sufficient to cover each of the
component parts of the bird, and these will enable you to reproduce them separately

Figure 3.23

at a convenient position to the right-hand side of the drawing (Fig. 3.23). You will note
that the centre lines move with each of the parts, and by superimposing the intersections
you will be able to reassemble the bird and also change, if you wish, the profile and the
orientation of the limbs. The centre lines act as datums.
Experiment by copying four birds and use the ROTATE command to alter the position of
the limbs in turn (Fig. 3.24). Note that the program requires you to draw a box surround-
ing the limb. Select the rotation point, then manually change the angle. The box may well
cover parts of other features, but only complete limbs within the boundaries will be
rotated as required on the assembly.
Baby birds look very much like their mothers and can easily be reared by using the
MIRROR feature, then the SCALE feature to make them younger. EDITthe shapes to give
finished profiles. A lot of fun can be had by changing feature shapes, orientation and
sizes.