|Among all of the creatures that live
in your Generic CADD drawing files, components are among the most fascinating.
In this month's column, we'll take a look at some of their more interesting
Did you ever zoom back and have things in your drawing change color? Those components are having fun with one of their little-know properties. Each placement has it's own color, which is used only when the component is too small to see the colors of the individual entities from which it was created.
This brings up a question...what color is a component, anyway? We know that everything in the drawing is some color, and components are no exception. The color of the lines, arcs, etc., inside the component are easy enough to see, but the component placement has its own color as well. The current color, layer, line type, and line width are all stored when the component is placed, although some of these are never used.
This concept helps to explain another component wonderment, the fantastic disappearing component. Under certain circumstances, which are not always easily explained, like during a full moon, when you explode a component it vanishes, only to reappear when you least expect it.
What has happened, as you have probably deduced by now, is that the component placement is on a layer that is currently displayed, but the individual entities inside the component were on layerrs that are currently hidden. While the component was still a component, you could see everything, but as soon as you exploded it - whamo! back to the original layer of the entities within.
You can test this out easily enough. Draw a rectangle on layer 1, using color 1. Now put a circle inside on layer 2, using color 2. Create a component of these entities called BOX (don't forget to have all layers turned ON), then go to layer 3, color 3, and place the BOX next to the original from which it was created.
Now make layer the current layer, and hide all layers (YH 256). Now explode the component and try hiding the layers again. Got it? Anytime you get vanishing components, type YD 256 and you'll probably find them.
I can't prove it, but the same is true for line type and line width as well. If you know how to show this one on the screen, drop me a line in care of the Generic Software News. Thanks.
After these musings, which are great fun, but of mainly concpetual value, I feel a responsibility to finish up with something more useful: renaming a component. There is no CADD command for doing this, but the following technique works:
Place one of the components to be renamed somewhere, with rotation zero and scale factors one. Next, explode it. Then create a new component with the new name, using the same reference point. Now, replace the new one for the old one with the CN command, and finally get rid of the old one for good with CX. Done.