What is a CAD shape file, and what is the difference between it and a font file?

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Recently, some netizens asked this question: What is a shape file? What is a symbol shape? In fact, this problem has been introduced in the previous article, but the symbolic shape was not introduced in detail at that time, and some statements were incorrect, so the following is a detailed introduction to the symbolic shape and its usage.

1. What is a shape file

The CAD font file *.SHX we usually download is the shape file.

The extension of the source file of the shape file is *.SHP [SHP is the abbreviation of shape (shape)], it is a plain text file similar to the fill and line type, but the definition is relatively more complicated, and the shape file is defined at the file header. Type and basic format, followed by the encoding and stroke definition of each character, as shown in the figure below.

If you can figure out what these codes mean, you can also write your own shape files or add characters to the files. After the *.SHP file is written, use the COMPILE command in AUTOCAD to compile it into a SHX file.

Shape files generally refer to all *.shx files. When some low-level versions open drawings and lack fonts, the command line sometimes prompts 'Shape ** is not defined'. We should first think of opening the text style dialog box to check if there are any. What font was not found.

What should I do if the CAD drawing will prompt that the shape is not defined?

I haven't studied these encoding definitions of shape files carefully. If you are interested, you can check the relevant instructions in the AUTOCAD help.

2. Classification of shape files

Shape files are divided into two types: fonts and symbol shapes (Shapes), and fonts can be divided into regular fonts (Unifont) and large fonts (Bigfont ).

Font files are used to write text or symbols. Regular fonts can also be called small fonts, which are used to write some single-byte characters and symbols, such as letters, numbers, steel bar symbols, etc. The commonly used ones are txt.shx, simplex.shx, tssdeng.shx, etc. Large font is a shape file specially defined for double-byte Asian characters, such as Simplified Chinese (hztxt.shx, tssdchn .shx, gbcbig.shx), Traditional Chinese, Japanese, Korean, etc.

When setting the text style ST, regular fonts will be displayed in the list on the left, and will be displayed together with the operating system fonts. If "Use large fonts" is checked, only the regular fonts of CAD will be displayed in the list on the left. As shown below.

Note: In the previous article, the gdt.shx used in the geometric tolerance labeling is a symbolic shape. Later, it was found that this statement was wrong. This file is a regular font file, but some special symbols are added in it, as shown in the figure below.

What does large CAD font mean? What is a shape file? Explain in detail the classification of CAD font files

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3. How to use symbols?

When opening the drawing, it prompts that the SHX file is missing. If a font file is selected for replacement, it prompts that the font is a regular font or a large font, not a shape file. The prompt information is as follows:

hztxt2.shx is a large font file, not a shape file.

Eref.shx is a regular font file, not a shape file.

At this time, the shape file in the prompt information refers specifically to the shape (Shapes) file, instead of referring to all SHX files.

The symbol shape contains some symbols (called in CADShape span>, this article calls them symbols and symbols just for easier introduction and description), these symbols can be used to define line types or directly inserted into drawings as graphics, common Symbol shape files include ltypeshp.shx, aaa.shx, etc.

In the regular font and large font list of the text style ST dialog box, the symbol shape file is not displayed, that is to say, the symbols in the symbol shape cannot be input as text.

There are two main usages of the symbol (shape) in the symbol shape file:

• Define Linetype

• Insert directly into the diagram

1. Define line type

Some complex line types have text and symbols (shape), and the definition of line types with text and symbols (shape) is different.

If you want to add text to the line type, you need to define a text style first, and then write the text and text style in the line type, for example:

*GAS_LINE,Gas line ----GAS----GAS----GAS----GAS----

A,12.7,-5.08,['GAS',STANDARD,S=2.54,U=0.0,X=-2.54,Y=-1.27], -6.35
*HOT_WATER_SUPPLY,Hot water supply ---- HW ---- HW ---- HW ---- HW
A,12.7,-5.08,[' HW',STANDARD,S=2.54,U=0.0,X=-2.54,Y=-1.27],-5.08

The above two line types use the STANDARD text style and add text such as GAS and HW to the line type. The line type varies with the font set in the text style, and the text effect will be different, as shown in the figure below.

And more line types directly use some graphics and symbols defined in the shape file, such as:

*TERRACE2,Second terrace__|_|__ __|_|__ __|_|__ __|_|__ __|_|__
A,.15,[8, aaa.shx,x=-.02,s=0.15],.15,[8,aaa.shx,x=-. 02,s=0.15],.15,-0.2

*ZIGZAG,Zig zag /////////////////////////////////////////// ///

A,0.00254,-5.08,[ZIG,ltypeshp.shx,x=-5.08,s=5.08],-10.16,

aaa.shx and ltypeshp.shx are symbol shape files, and the preceding 8 and ZIG are the names or codes of the symbols. If you want to use the shape file to define the linetype, you must have a certain understanding of the names of the shapes contained in the linetype and the corresponding graphics.

Teach you how to customize CAD line type

2. Directly insert symbols (shape) into the diagram as graphics

Although the symbols in the shape file cannot be input as text, they can be directly inserted into the diagram as graphics. The operation method is as follows:

1. Use the load command to load the shape file (*.shx), and load the symbols (shape) in the shape file.

2. Enter the SHAPE command, press Enter, enter the name of the shape according to the prompt, set the scale and direction, and then insert these symbols (shape) into the drawing, as shown in the figure below.

3. How to know which symbols are in the shape file?

The key is how do we know which symbols are in the shape file, and what are the names of the symbols?

It is relatively simple to know the names of these symbols. After loading the shape file with the LOAD command, enter the SHAPE command, press Enter, and enter? No., press Enter, and then press Enter, you can list the names of all available shapes that are currently loaded, as shown in the figure below.

There are only six symbols in Ltypeshp.shx. You can roughly understand the shapes of these symbols from the names, such as BOX and CIRC1. Even if you insert all of them, it is not difficult to look at them, as shown in the figure below.

Note: The last symbol, AMZIGZAG, which is similar to a broken line, is much larger than other symbols. The above picture is the effect after being reduced by dozens of times. I don’t know what special purpose this symbol has.

However, aaa.shx contains dozens of symbols, and the code names are all numbers, ranging from 1 to 5 digits, which is not easy to remember clearly. If you want to use the symbols in aaa.shx, you can use the font viewing tool shared before, open aaa.shx and save it as aaa.shp file, open the aaa.shp file with Notepad, and find the symbols you want to use in the viewing tool Finally, double-click to display the detailed information of the symbol, and then find the code corresponding to the symbol in the aaa.shp file according to the number, and finally insert the symbol into CAD for verification, as shown in the figure below.

CAD shx font file viewing tool

Summary

Shape files can generally refer to all *.shx files, including regular font Unifont, large font Bigfont and symbol Shapes; but in the prompt information inside the CAD software, it usually refers specifically to symbol shapes (*.shx files whose type is Shapes), not Include font files.

Unlike font files, symbol shape files cannot be used to define text styles, that is, they cannot be used to write text, but can be used to define line types or be inserted into drawings as graphics.