Chapter 31 Creating Your Own Linetypes and Hatch Patterns 931

Figure 31-11: The lightning hatch pattern.

Check out the acad.pat or aclt.pat file for some ideas on how to create your own hatchpattern definitions.

Summary

In this chapter, you discovered how to create your own linetypes and hatch patterns. You read about the following:

Creating simple linetypes containing only dashes, dots, and spaces

Making complex linetypes that include shapes and text

Constructing your own hatch patterns that are made up of a set of parallel lines In the next chapter, you read about how to create shapes and fonts.

Creating Shapes

and Fonts

Shapes are similar to blocks. You create them, store them, and insert them.

AutoCAD LT doesn’t offer the shape feature. This entire chapter applies to AutoCAD only.

There are several differences between shapes and blocks:

Shapes are much harder to create.

Shapes are compiled into a format that conserves storage space, memory, and regeneration time.

You can use shapes to create fonts.

Font and shape files are support files — if you distribute

a drawing, be sure to include any font or shape files that the drawing uses.

You can use shapes for simple forms that you need to insert many times quickly. Examples are shapes inserted into complex linetypes and font characters.

Creating Shapes

Shape files are used for both shapes and fonts. You create them with a text editor and save them with the extension .shp. You then use the COMPILE command (on the command line), which opens the Select Shape or Font File dialog box, shown in Figure 32-1.

Choose the .shp file and click Open. AutoCAD automatically compiles the file into a new file with the same name but with an extension of

.shx, and displays a message on the command line that compilation succeeded.

32C H A P T E R

In This Chapter

Creating shapes

Creating fonts

934 Part VI Customizing AutoCAD

Figure 32-1: The Select Shape or Font File dialog box.

Using shape files

After you have a compiled shape file, you must load it with the LOAD command before you can place it in a drawing. The Select Shape File dialog box opens. Choose the .shx file and click Open. Font files don’t have to be loaded because they’re automatically referenced by text styles that use the font files.

To insert a shape, use the SHAPE command prompts as follows:

1.Enter shape name or [?]: Type the name of the shape or type ? to get a list of loaded shapes.

2.Specify insertion point: Pick a point on the screen. AutoCAD drags the shape as you move the cursor.

3.Specify height <1.0000>: This functions like a scale factor. For example, type

.5 to insert the shape at one-half its original size.

4.Specify rotation angle <0>: Type a rotation angle.

Creating shape files

Shape files and font files are essentially the same. In this section, I explain how to create shapes. At the end of the chapter, I explain the few distinctions necessary to create a font file.

As with most customizable files, you use a text editor to create shape files. You can add comments following a semicolon. A shape definition has the following syntax:

*shapenumber,#ofspecs,SHAPENAME spec1,spec2,...,0

The definition must start with an asterisk. Each line cannot contain more than 128 characters. Table 32-1 explains the parts of this shape definition.

Chapter 32 Creating Shapes and Fonts 935

	Table 32-1: The Parts of a Shape Definition
Item	Explanation
shapenumber	You can use any number from 1 to 255. Each shape in a file must have a unique
	number.
#ofspecs	This is the number of specifications in the second line of the definition, including
	the mandatory 0 at the end.
SHAPENAME	You must use uppercase for the shape name. This is the name you use with the
	SHAPE command.
spec1...	This is a code that defines the actual shape. Each specification code defines a
	part of the shape, such as a line segment or an arc. Together, all the specifications
	draw the shape.
0	The definition must end with a 0.

Length and direction codes

You can use two sets of codes to define a shape. The first set — the length and direction codes — only lets you draw straight line segments. You use this system to create specifications in the three-character hexadecimal format.

The first character is 0, which tells AutoCAD that the next two characters are hexadecimal values.

The second character is a length in units. The maximum is 15 units. The number values can range from 0 to 9. For values from 10 to 15, use A to F. However, the length is measured along the nearest X or Y distance. Therefore, diagonal lengths are not true lengths.

The third character is a direction code. Figure 32-2 shows how this code works. Use the code that represents the desired direction of the line from the start point.

Figure 32-2: The direction codes.

Here is the code for the shape shown in Figure 32-3:

*2,4,PENNANT

044,02F,029,0

936 Part VI Customizing AutoCAD

Figure 32-3: The PENNANT shape.

Here’s how this shape works:

2 is the shape’s unique number.

4 is the number of bytes (specifications) on the second line of the definition.

PENNANT is the shape’s name.

044 draws the pole, a line that is 4 units in the vertical direction.

02F draws the top line of the pennant, a line that is approximately 2 units in the F direction. (See the following note.)

029 draws the bottom line of the pennant, a line that is approximately 2 units in the 9 direction. (See the following note.)

Note	Although the length of the two diagonal lines was specified as 2, they’re actually about 2.22
	units long because the line endpoints snapped to the nearest imaginary grid point.

Supplemental codes

The length and direction codes have a number of limitations:

You can draw in only 16 directions.

The maximum length of a line is 15 units.

You can only draw straight line segments.

The shape has to be continuous — you cannot lift the “pen” up and start in a new place.

The second set of codes, the supplemental codes, brings additional flexibility (and complexity) to your shapes. Table 32-2 lists these codes, which can be in either hexadecimal or decimal format.

Table 32-2: Supplemental Shape Codes

Hexadecimal Code	Decimal Code	Explanation
000	0	Specifies the end of the shape definition.
001	1	Starts draw mode (puts the “pen” down).
002	2	Ends draw mode (lifts the “pen” up) so that you can move to a
		new location.
003	3	Divides the vector lengths by the specification that follows, as in
		3,5 to divide the lengths by 5. This scales down the shape. You
		should reverse this at the end of the shape by using the 4 code.

Chapter 32 Creating Shapes and Fonts 937

Hexadecimal Code	Decimal Code	Explanation
004	4	Multiplies the vector lengths by the specification that follows, as
		in 4,2 to multiply the lengths by 2. This scales up the shape. You
		should reverse this at the end of the shape by using the 3 code.
005	5	Saves the current position so that you can return to it later in
		the shape definition. You must use (restore) every position you
		save (with a maximum of four).
006	6	Restores the last saved position.
007	7	Draws another shape defined within the same shape file,
		whose number follows. For example, use 7,230 to draw shape
		230. When the other shape is complete, AutoCAD returns to
		the current shape definition.
008	8	Draws a line specified by X and Y displacements that follow the
		code. For example, 8,(8,–12) draws a line whose endpoint is 8
		units to the right and 12 units down from the current coordinate.
		(You can add parentheses to your shape codes for readability.)
009	9	Draws multiple X,Y displacements. You end this code with a
		displacement of 0,0. For example,
		9,(8,–12),(1,0),(0,12),(–8,0),(0,0) draws four X,Y displacements.
		(You can add parentheses to your shape codes for readability.)
00A	10	Draws an octant arc specified by its radius (ranging from 1 to
		255), and a second code in the syntax (–)0SC where the
		minus optionally indicates a clockwise arc, the 0 is mandatory,
		S specifies the starting octant, and C specifies the number of
		octants that the arc covers. An octant is an eighth of a circle.
		Figure 32-4 shows the octant codes you must use for the
		starting octant. For example, 10,(2,014) indicates an arc with a
		radius of 2 that is drawn counterclockwise from octant 1 and
		covers 4 octants (ending at octant 5). This is a semicircle.
00B	11	Draws a fractional arc not limited by octants specified by
		the five following codes in the syntax: start_offset,
		end_offset,high_radius,radius,(-)0SC. The start
		offset specifies how far past an octant the arc begins and is
		calculated as follows: (starting degrees – degrees of the last
		octant passed) * 256/45. The end offset specifies how far past
		an octant the arc ends and is calculated as follows: (ending

degrees – degrees of the last octant passed) * 256/45. For both the start and the end of the arc, the last octant passed is specified in degrees, not the numbers in Figure 32-4, and is always a multiple of 45. The high radius is 0 unless the radius is more than 255. If your radius is larger, the high radius is the maximum number of 256 multiples in the value of the radius (for example, 2 if your radius is 600). The difference (the radius minus 256 times the high radius value, or 88 if your radius is 600) is placed in the radius specification. The radius is just the radius of the arc. The (–)0SC part of the code is the same as for code 10 (00A) except that S is the octant the arc starts in and C is the number of octants the arc covers.

Continued

938 Part VI Customizing AutoCAD

Table 32-2 (continued)

Hexadecimal Code	Decimal Code	Explanation
00C	12	Draws an arc using a system of X,Y displacement and bulge
		specified in the following three codes using the syntax X-
		displacement, Y-displacement, bulge. These three codes can
		range from –127 to +127. The X and Y displacements just
		specify the endpoint of the arc. The bulge equals ((2 * H/D) *
		127) where D is the chord length (the distance from the start
		point to the endpoint) and H is the height measured from the
		midpoint of the chord to the circumference of the arc. The
		bulge should be negative if the arc is drawn clockwise.
00D	13	Draws multiple arcs using the X,Y displacement and bulge
		system. End the arcs with (0,0). You can use 0 for a bulge to
		place a line segment in the midst of several arcs.
00E	14	This code is used only for text fonts that can be used in the
		vertical orientation (each letter is drawn under the previous
		letter). When the vertical orientation is chosen, the
		specifications after this code are used. Use this code to move
		the starting and ending point of letters to a point appropriate
		for vertical orientation (that is, on top of and below the letter).
		See the “Creating Fonts” section later in this chapter for more
		information.

2 (90°)	Figure 32-4: The codes for octant arcs.
3 (135°)	1 (45°)
4 (180°)	0 (0°)
5 (225°)	7 (315°)
6 (270°)

All these codes can seem pretty overwhelming. The most common use for shapes is for fonts. Here are a few examples:

*3,22,ALEF

010,07E,010,2,8,(–6,5),1,8,(–2,–4),01C,2,8,(5,2),1,8,(2,4),014,0

This is a squared-off alef, the first letter of the Hebrew alphabet, as shown in Figure 32-5. Displaying non-Roman fonts is a common use for shapes.

Planning in advance is almost essential. A common technique is to draw the shape in a drawing on a grid set to 1-unit spacing. You can use only integers in your shape codes, so you must often scale the shape up so the smallest line segment is 1 unit.

Chapter 32 Creating Shapes and Fonts 939

Figure 32-5: A squared-off alef.

Here’s how the code for the alef works:

The shape starts at the top left. The code 010 is a hexadecimal length and direction code and specifies a line with a length of 1 unit and a direction of 0 degrees.

The second code, 07E, is also a hexadecimal length and direction code. It specifies a line with a length of 7 units in the E direction (315 degrees). The line is not actually 7 units long, but its X (and in this case Y) distance is 7.

The third code, 010, is the same as the first code and ends the first set of line segments.

The fourth code, 2, lifts up the pen so that you can move to the start of the next line.

The fifth code, 8, indicates that the following two codes will be an X,Y displacement.

The sixth and seventh codes, (-6,5), are placed in parentheses for readability. They move the pen (while it is up) –6 in the X direction and +5 in the Y direction from the end of the last line to the start of the next line. (Count the grid dots to find it.)

The eighth code, 1, puts the pen down so that you can draw.

The ninth code, 8, is the same as the fifth code.

The 10th and 11th codes, (-2,-4), draw the first segment of the second line so that the endpoint is –2 units in the X direction and –4 units in the Y direction from the start point.

The 12th code, 01C, is a hexadecimal code and finishes the second line with a 1-unit line segment in the C direction (270 degrees).

The 13th code, 2, lifts up the pen again.

The 14th code, 8, is the same as the fifth code.

The 15th and 16th codes, (5,2), move the pen (which is up) +5 in the X direction and +2 in the Y direction.

The 17th code, 1, puts the pen down again.

The 18th code, 8, is the same as the fifth code.

The 19th and 20th codes, (2,4), draw a line whose endpoint is 2 units in the X direction and 4 units in the Y direction from its start point.

940 Part VI Customizing AutoCAD

The 21st code, 014, is a hexadecimal length and vector code and draws a 1-unit line in the 4 (90-degree) direction.

The 22nd code, 0, ends the shape definition.

Here’s another example — in this case, a script alef — shown in Figure 32-6:

*4,10,S-ALEF 06C,2,8,(6,5),1,10,(3,016),0

Figure 32-6: A script alef.

Here’s the explanation of the code for the script alef:

On the

CD-ROM

The first code, 06C, creates the line on the left, starting at the top and making it 6 units long.

The second code, 2, lifts up the pen.

The third code, 8, specifies an X,Y displacement, with the pen up.

The fourth and fifth codes, (6,5), move the pen 6 units to the right and 5 units up, to the start of the arc.

The sixth code, 10, introduces an octant arc.

The seventh and eighth codes, (3,016), specify an arc with a radius of 3 that starts at octant 1 and covers 6 octants (to octant 7). (See Figure 32-4 to review the octant codes.)

The last code, 0, ends the definition.

The Express Tools contain a command, MKSHAPE (choose Express Tools Make Shape) that makes shapes for you. You just draw the objects.

The drawing used in the following Step-by-Step exercise on creating a shape, ab32-a.dwg, is in the Drawings folder on the CD-ROM.

Chapter 32 Creating Shapes and Fonts 941

STEP-BY-STEP: Creating a Shape

1.Open ab32-a.dwg from the CD-ROM.

2.Save the file as ab32-01.dwg in your AutoCAD Bible folder. This drawing shows an uppercase P, with dashed lines to indicate space before and after the letter, as shown in Figure 32-7. This is the type of drawing that you might use as a basis for creating a shape definition.

Figure 32-7: An uppercase P.

3.Type notepad on the command line and press Enter at the File to edit: prompt to open a new file.

4.Type the following in Notepad:

*80,15,UCP

2,030,1,0E4,020,12,(0,–8,–127),028,2,8,(9,–6),0

5.Press Enter at the end of the last line. Choose File Save in Notepad and save the file in your AutoCAD Bible folder as ab32-01.shp. Close Notepad.

6.In AutoCAD, type compile . Double-click ab32-01.shp. AutoCAD compiles the .shp file. AutoCAD confirms on the command line that the compilation succeeded. (Press F2 to open the Text Window if necessary.)

7.Type load and choose ab32-01.shx. Click Open. Type shape . To insert the shape, follow the prompts:

Enter shape name or [?]: ucp

Specify insertion point: Pick any point. Specify height <1.0000>:

Specify rotation angle <0>:

8.Save your drawing. It should look like Figure 32-8.