Useful hints from CADD Primer:
Displaying a Full View
CADD allows you to display the entire drawing on-screen regardless the size of the drawing. If the drawing is too large, CADD automatically reduces it to fit the drawing area. If the drawing is too small, CADD automatically enlarges it to fill the drawing area.
Example: If you draw a 1”x1” square and display a full view of the drawing, it magnifies the image to fill the entire screen. Now let’s say you draw a 10’ diameter circle around the square and then display a full view. It will automatically reduce the entire image to fit that circle on the screen. The square will be reduced significantly and might look like only a dot.
Fig. 4.3 (Screen 1) illustrates how you can display the entire drawing (Fig. 4.2) to fit on-screen by clicking on the full view tool button.
Fig. 4.3: The drawing image can be enlarged, reduced or moved using view-display functions.
Moving the View
You can move the image in any direction with the push of a button. This capability of CADD is often referred to as ”pan”. To move the image, all you need to do is indicate two points between which the drawing should move. The drawing is moved from the first indicated point to the second indicated point. Screen 2 (Fig. 4.3) shows how you can move the drawing to the left by indicating points A and B.
In some CADD systems the same result is achieved by pressing the arrow keys on the keyboard or by using the scroll bars on the screen. The drawing is moved in the direction of the arrow key pressed. You can preset a percentage of how much the drawing should move with each press of an arrow key.
Zoom-in and Zoom-out
CADD allows you to reduce or enlarge the image view by a specified degree. You can enter a specific percentage or a zoom factor to reduce or enlarge an image. To enlarge the image 1 1/2 times, you need to enter the percentage value as 150% or the zoom factor as 1.5. To reduce the image by half, you need to enter the percentage value as 50% or zoom factor as 0.5.
Most of the CADD programs provide tool buttons that allow you to instantly zoom-in and zoom-out by a predefined percentage. For example, clicking on the zoom-in tool button enlarges the image by 150% and clicking on the zoom-out button reduces the image by 50%.
Screen 3 (Fig. 4.3) shows how you can reduce the image shown on Screen 2 by 50%. Simply click on the zoom-out tool button and the image is reduced as shown.
Enlarging View by Indicating a Window
You often need to enlarge drawing images in order to work with a greater detail. You can specify an area to be enlarged by designating an enlargement window on the screen. A window is an imaginary rectangle formed by two diagonal points. The section of diagram contained within the window is enlarged to fit the entire drawing area.
Fig. 4.4 shows how you can enlarge a portion of the diagram by indicating a window. Screen 1 shows the full view of the drawing. Click on the zoom window tool button to enlarge a corner of the drawing and enter points A and B as the corners of the enlargement window. The view is enlarged as shown on Screen 2. To view the drawing in more detail, enter the zoom window command again and enter points A and B as the corners of enlargement window. The view is enlarged as shown on Screen 3. Similarly, enlarge the view again to see the drawing in more detail as shown on Screen 4.
Fig. 4.4: Views of the drawing are enlarged using view-display functions.
Saving and Displaying Views
CADD allows you to store selected views and later display them back when required. When you are working with complex drawings, you need to display a number of views quickly. This function provides a convenient way to display selected views.
When you determine that you need to work on certain portions of a drawing frequently, you can store those views by giving them different names. To display any of the views, just reference the name of the view and it is instantly displayed.
Displaying Previous Views
CADD makes it easy to return to previously displayed views. Just click on the tool button designated to display the previous view and you are returned to the last view displayed. This feature is extremely useful because you often need to return to the portions of the drawing where you were recently working. By using this function, you can display all the previous views one by one by entering the function again and again. Some programs also allow you to display subsequent views after you return to previous views. You can go back and forth between all the views just by clicking on a tool button.