Graphics Programs Reference
In-Depth Information
U s I n g a U t o Cad' s t r a d I t I of in a l C o l o r s
The traditional set of 255 colors for AutoCAD is set up in such a way that
the first seven colors are named (Red, Blue, and so on) and numbered (1
through 7), whereas the other 248 colors have only numbers.
As you saw on the Index Color tab of the Select Color dialog box, AutoCAD
has three groupings of colors: a large array of swatches in the top half and
two rows of swatches below. Moving the cursor over a swatch displays its
AutoCAD number below the array as well as its Red, Green, Blue (RGB)
values. The RGB values are the amount of each color, a number from 0
(none) to 255 (all), that is mixed with the other two base colors to make the
selected color. Click a swatch to assign it to the layer that has been selected
in the Layer Properties Manager dialog box.
You should avoid using colors that resemble the background color, such as
colors 250 or 18 with a black background. The objects with these colors could
become visually lost in the drawing area. Be aware of this if your drawings
might be sent to someone who doesn't use your color standards so that they
can work efficiently with the drawings.
the Array of 240 Colors In the top half of the dialog box are col-
ors numbered 10 through 249, arranged in 24 columns, each having 10
swatches.
the Row of nine Standard Color Swatches This group includes col-
ors 1 through 9. The first seven colors in this group also have names: Red
(1), Yellow (2), Green (3), Cyan (4), Blue (5), Magenta (6), and White/
Black (7). Colors 8 and 9 have numbers only. Color 7 is named White, but it
will be black if you're using a white background color.
the Row of Six Gray Shades These colors are often assigned screening
values (such as 50 percent, 75 percent, and so on), numbering 250 through
255. As pure color assignments, they range from almost black to almost white.
These 255 colors, plus the background color, make up the traditional AutoCAD
256-color palette. Two additional colors are in a group by themselves, Logical
Colors, and are represented by buttons on the Index Color tab.
The two buttons in this grouping — ByLayer and ByBlock — represent two
ways you can assign a color to objects — such as lines, circles, text, and so
on — via the layer they are on or via the block they are part of, rather than
to the objects themselves. (I'll cover blocks in the next chapter.) When you
assign cyan to the A-WALL layer and place all objects representing walls on
that layer, all wall objects are automatically assigned the color ByLayer and
take on the color of their layer — in this case, cyan.
(Continued)
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