Tuesday, February 19, 2008

Using Masks in AutoCAD to cover underlying features (hiding transparency)

In most programs, hiding underlying features is easy, but, in AutoCAD’s polygon/polyline based interface it is less easy. This article will outline three methods for whiteing out backgrounds in AutoCAD.

1) Text Masking: If you want text to have a black background (ie. White), enter the mtext properties, select “background mask” and click to select a mask that matches your background color (which may or may not be white). You can also use this command to select a colour of your choice to mask the text. Background masking can also work for other types of features and will be discussed at length in a future article.

2) The ‘wipeout’ command: this works well for an areal feature, like a polygon that surrounds text ie. Text in a box. Type the command wipeout, hit p for polyline, select the box surrounding your text in AutoCAD, then choose not to erase the box (obviously). What this will do is cover all of the features behind the feature you have selected. One draw back to this command, I find, is that when you re-open the document later, a bug often shifts the layer ordering, messing up what you have done. Silly AutoCAD!

3) Finally, when all else fails, a simple hatch can cure your AutoCAD woes. Select the polyline you wish to hide the interior of, type hatch (or h for short), choose solid color, then select the colour that matches your background by default.

Well, these three somewhat annoying to use commands are the only way, that I know of, to grey out background items in AutoCAD 2008. You should now be able to do away with transparencies in all of your CAD .dwg files. Hopefully.