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Text File | 1994-05-15 | 13.4 KB | 251 lines

DXF2HSH DXF polyline/polygon to DXF 3D Face converter by Vance Gloster May 1994 based on DXF2TRI DXF polyline/polygon to triangle converter by Tim Riley Aug 1993 based on POLY2TRI - a polygon to triangle converter by Steve Anger Jan 1993 This program is commited to the public domain. Feel free to use all or part of this code in your own programs. If you simply MUST show gratitude, send Animation Master .seg and .fig files for something cool you've created or a favorite bitmapped texture to my internet email address, vance@netcom.com. This is a utility that extracts polyline shapes from a DXF file and breaks them down into individual triangles. The polylines are assumed to be closed, planar (2D) polygons. This program only deals with POLYLINE entities and ignores all other entities in the DXF file. All properties (color, line type) are ignored. The input DXF file consists of one or more polylines with no more than 2000 vertices. This limit is rather arbitrary and can be changed if necessary by changing POLYMAX. The program uses the following syntax: DXF2HSH infile[.DXF] outfile[.DXF] [xy] The xy switch when added at the end modifies the plane that it extracts the polygons from. The software I use, 3d Font, ouputs DXF files in the XZ plane as do some other programs. My understanding is that Corel Draw 4.0 outputs DXF files in the XY plane, so this switch should be used if you are exporting drawings from Corel. Using the wrong setting on this switch usually results in the object that you import being just a line with a bunch of control points on it. The output file is a DXF file which consists of 3D Face objects, one for each triangle. So what is the program good for? The program I use to do 3D rendering is Animation Master from Hash, Inc.who also make Playmation. They have included a limited utility for importing DXF files. This was designed to be used with DXF files created by a company (whose name I have forgotten) that makes high quality models of almost anything and sells them for more money than I can afford. These models consist of triangles expressed as 3D Face objects. Since the import utility was only designed to read this format, it does not read DXF files that have the more common POLYLINE objects. What *I* wanted to do was to import text using fancy fonts. I found a Windows program called 3D Font by a company called Visual Software which will accept text and output a DXF file using any TrueType font. Unfortunately, these DXF files consist of POLYLINE objects. To make a long story short (too late) my program converts the output of 3D Font into a format that you can import into Animation Master. The code to read the POLYLINE DXF file and break it into triangles was in the program I derived this program from. I merely modified the POLYLINE reader to use either the y or the z as the second dimension of the POLYLINE construct which 3D Font uses for some reason. I added the code to output the 3D Face objects. To figure out what was required I merely created a couple of triangles in the Sculpture module of Animation Master and output them as a DXF file and emulated the form, assuming that whatever it could output it should be able to input. I was fortunate in finding a program that had most of the pieces I needed already done. Thanks, Tim! Thanks Steve! This archive should contain the following: DXF2HSH.C The source DXF2HSH.EXE The executable, compiled with Microsoft Visual C++ 1.5, medium memory model. No extenders, no memory tricks, so you don't have to worry about EMM386 and it's ilk and it runs fine from within Windows. DXF2HSH.MAK Visual C++ make file. DXF2HSH.DOC This file. V.DXF The output of 3D Font of a capital V in Times New Roman font. VH.DXF V.DXF converted by DXF2HSH. V.SEG VH.DXF imported into the Sculpture module of Animation Master. Here are the steps for using DXF2HSH with 3D Font and Animation Master. A similar process should be possible with most Windows drawing programs like Corel, Micrographix Designer, Adobe's drawing program, etc. 1. Use 3D Font to generate a DXF file of your text. If you are using some other package, make sure that you convert all curves to line segments (POLYLINES). 3D Font does this automatically. In 3D Font use the "Save 2d..." option to create the file. In any other package, make sure it creates a 2D DXF file, not a 3D DXF file. Assume for the purposes of this example that you have created a DXF file called MYTEXT.DXF. My test was performed with version 2.0 of 3D Font. 2. Run the DXF2HSH utility. For our example the command string is: DXF2HSH MYTEXT AMTEXT 3. Run the Sculpture module of Animation Master. Under the File menu select "Import DXF...". Select AMTEXT.DXF in the dialog box that comes up. You will see your text appear. Make sure that you have version 2.04 or later of Sculpture (the version number is in the About box) because previous versions had a bug in DXF import. 4. For best results, at this point select "Select All" from the Group menu, and then Peak Grouped Points. You can do this by either typing 'K' or pressing the button with the icon that looks like this: . ./ \. with stright lines. This makes the triangles operate the way they are supposed to with straight lines. 5. Since the imported object is only 2D, you will probably want to extrude it. Since there are often LOTS of control points (because these are triangles), this operation may be very sluggish. Be patient, if you wait long enough I have found that eventually Animation Master does what it is supposed to. 6. Since the objects created this way have lots of control points they tend to render a little slower. I have had some luck simplifying the models by removing control points and extra lines. Simple fonts like Arial are not too bad. The complex fonts like Chili Pepper contain an amazing number of points. Try doing this first with Arial before you get extreme. Below are the directions that came with the program I derived DXF2HSH from. They may help people with using Corel, but the predecessor program was designed to create a format used by POV, a public domain raytracer. I have experimented a lot with the tools I have and have not encountered the problems he tries to solve in step 2 below. I have imported both 'O' and '&' without any difficulties. He talks about an extrude function which is disabled in my program because Animation Master's extrude feature is more useful. The code for extruding is still included in the source if you are an ambitions C programmer and need this feature. If you have problems with a particular DXF file, I make no promises about fixing it or providing support. Your best shot is to create the SIMPLEST DXF file that exhibits the problem, and email it to me at my internet address vance@netcom.com along with a BRIEF description of the problem. I will fix it if I have time. Good luck! -Vance Gloster May 15, 1994 (Documentation for DXF2TRI) To keep things straight forward, here is how I put text in a scene (NOTE: I am assuming a reasonable knowledge of CorelDraw. This method should be possible with other Windows draw (NOT paint) programs such as Micrographix, Adobe Draw (Designer?) and others, none of which I have any experience with, assuming they have the following capabilities: * can export a DXF file * converts curves to line segments (POLYLINES) otherwise, you're out of luck): 1. Use Corel (4.0) to generate the initial text. Overall size and position is not important since you will scale and position it later on. Line properties (type, thickness or color) are irrelevant since they will be ignored, as well as fill properties. 2. Dealing with holes: re-entrant (concave) portions of a letter appear to convert with no problems (the m and & of the test image seem to prove this). Holes are another matter. In the simplest view, they are another object/curve. Since the objects will be converted to 2D triangles, CSG cannot be used to subtract them from the main object. The easiest solution I have found is to make all holes part of the main object's outline. This is accomplished in two steps: a. Convert the letter from text to a curve. Do this after you have done all of the transformations you care to do on your text. You cannot convert from curves back to text (well you can, in a way, but font creation is beyond to scope of this babble). b. Using the node edit tool, cut a channel of zero width between the hole and the outside of the curve/letter. This can be done anywhere. As long as the sides of the channel touch, there will be no visible effect on the finished product. For example: Turn: into: *** *** *** *** *** *** ** ** ** ** ** *** ** ** *** ** * ** ** * * ** ** * * ** ** * * ** ** * * * * * * * * * * * * * * * * * * * * * * * * * * ** ** * * ** ** * * ** ** * * ** ** * ** *** ** ** * * ** ** ** ** * * ** *** *** **** **** *** * * These segements overlap --->| |<--- If you want to be artistic, you can cut the channels in obvious places, where a curve intersects a straight segment, for example. I broke the ampersand in the following places: *** * * * * * \ \* * * * * * * * * * * * and then removed the unnecessary nodes on the straight line segments. This has the added effect of reducing the number of vertices of the polyline, as well as the number of triangles and the complexity of the final object. 3. Export the text as a DXF file. The Corel 4.0 DXF filter converts all curves to line segments. It allows you to choose the number of line segments a curve is converted to. I chose 32 (the minimum value) to minimize the complexity of the object. There is no visible degradation to the object when rendered at 1024x768 (and, I suspect, greater). Individual letters may be exported to separate DXF files if you want to texture them separately. The COREL-DXF-RAW-POV conversion chain retains the relative position of each letter, but they become separate objects and inter-letter spacing becomes a problem unless you first combine them as a composite in the scene file before performing any transformation. If you are going to texture the text uniformly, it is easier to export the text to a single DXF file and treat it as a single object. 4. Run DXF2TRI on the DXF file to generate a RAW file. If you want to extrude the letters, use the -e switch. If the back of the letters will be visible (due to reflections or camera position), use the -b switch to generate solid backs to the letters. 5. Run RAW2POV on the RAW file. RAW2POV will generate a POV file giving the physical limits of the object(s) and an INC file consisting of triangles, smooth triangles and bounding shapes. The rest is up to you. No, its not overly easy or straight forward, but it works well and the results aren't bad. Before anyone has a chance to ask or comment, no it won't bevel, but I am thinking of it. A straight bevel should be possible, but a curved (routed) bevel will take some doing, since CSG won't work with triangles. Don't let me stop anyone else from working on the problem, since I have a lot of other things to keep me busy. I assume NO responsibility for this program or its effects, but if you need to contact me, for whatever reason, I check in occasionally to The Graphics Alternative and my Internet address is: triley@its.bldrdoc.gov. Doo dah.