Technical Q&A QD3D19

Use QuickDraw 3D B1C3 Library to Eliminate User Breaks

Q: I built a very simple file in 3DMF binary format. Tumbler can read it, but Metafile Read cannot (a user break appears). Typing "g" in MacsBug allows Metafile Read to recover and show the cube. I also get a user break with this file in my application, which uses the code from the Tumbler example. The user break in MacsBug is crashing the Metrowerks Debugger, so I am forced to debug with DebugStr. Is there a workaround?

A: You should be able to eliminate the user break problem by replacing your current library with the QuickDraw 3D B1C3 library, which is posted on AppleLink and on the Apple FTP site. The updated source for the metafile-read snippet is also available at these sites. Earlier versions of the library had a number of problems reading metafile data, but these problems have been eliminated in the B1C3 build.

The problem of DebugStr crashing the Metrowerks Debugger can be caused by an odd combination of CodeWarrior, the System 7.5 update, and PowerMac debug services. If you are using CodeWarrior 5.5, you should upgrade your copy of DebugServices to the most recent version. If you are using CodeWarrior 5.0, try removing the system update (unfortunately, the only way to do this is to re-install System 7.5).

Also, if you are using the Metrowerks Debugger and you find yourself in MacsBug, you can propagate the exception (in the case of PowerPC exceptions) to the high-level debugger by typing GP in MacsBug.