A small number of users have reported either Error 75 or Error 76, which typically occurs in the doGemRay routine or PGemRay routine. These are the subroutines which communicate with GemRay via the DOS window. Reliable communication between Windows programs like BOG and pure DOS programs like GemRay is very poorly supported. The only completely safe way I have found is to copy the GemRay command to the clipboard and then paste it into the DOS window. This will fail, usually with Error 75 or 76, if this communication pathway is interrupted.
Such interruption can occur if other programs are running in the background. In the two or three cases reported so far, Norton AntiVirus has been the culprit. Try disabling this program before running BOG. Also, it is probably a good policy not to have other programs running during a BOG session.
Make sure COMMAND.COM is in your path. It usually resides in the C:\WINDOWS directory. Run MSCONFIG from the "Start" menu. Check under the Autoexec.bat panel that the C:\WINDOWS directory is in the path.
Symptom: The DOS window freezes in the middle of a Gemray calculation. The DOS window content appears normal (no error message) but frozen. Possible cause: Clicking in another window removes the focus from Gemray, and the program suspends operations. Try clicking on the DOS window to return control to Gemray.
Symptom: The DOS window freezes. BOG appears to hang after calling Gemray (white on red Gemray call in the Status Window. Possible cause: An invalid command has caused a less-than-graceful exit from the Gemray program. Usually, some hint of the cause appears in the DOS window, so enlarge it if necessary to see the error message. If the window disappears too rapidly to see any message try the following: Start BOG, then click in the DOS window and enter "command.com /p". This will cause a "permanent" DOS shell to execute - in other words, an error will not cause the window to disappear. Reproduce the conditions which caused the problem and note the error message in the DOS window. You will probably have to explicitly close this "permanent" DOS window by clicking in the Close Box (X), since the "exit" command will no longer work.
Symptom: The DOS window behaves strangely, perhaps with a dangling pop-down menu. BOG does not start properly or appears to hang after calling Gemray (white on red Gemray call in the Status Window). Possible cause: BOG communicates with the DOS window running Gemray by copying a command to the clipboard, then invoking the Windows-standard Paste sequence. For US-English systems, this is <alt-space E P>. This sequence can be different in different countries. Determine how to paste text into a DOS window by clicking on it then hitting <alt-space>. A drop down menu should appear. Navigate to the paste command and note the relevant keystrokes. In Germany, these are <alt-space B E> (for Bearbeiten -> Einfugen). Enter this sequence into the Customize BOG dialog box (About BOG --> Customize BOG) and click Ok. Note that the % corresponds to Alt, and that you must explicitly include the space after the %. Quit BOG and close the DOS window. The DOS window paste sequence will be loaded automatically from BOGPrefs.txt the next time you start the program. Hint: Strange Raytrace Output may also occur on non-English Windows system. See the tip below.
Symptom: Gemray seems to be producing incorrect output for apparently reasonable parameters. Often the raytrace will be black. The same parameters produce reasonable output when you run Gemray interactively. Possible cause: BOG communicates to Gemray via the Clipboard copy and paste. Sometimes, Windows will change the number format of text copied and pasted in this way based on the "standard" number format. For example, in many European countries, the comma and decimal point are used in the exact opposite sense as in North America - the decimal acts as the thousands separator, and the comma is the decimal separator (one cent less than a million dollars is $999.999,99). You can check this by opening the Notepad and pasting (Ctrl-V) the contents of the clipboard into an empty document. Check the number format carefully - Gemray only accepts North American conventions for numbers. Workaround: Try using the batch file option (see Performance Problems below). The other workaround is to change the default number format in the "Regional Settings" control panel.
BOG may appear sluggish, particularly in communicating with the DOS window. For some reason, on some Windows systems, the inter-application communication is really SLOW. I have seen it take just as long to paste the "Gemray" command into the DOS window as it does to execute the raytrace! To speed things up, there is an option to use .BAT (batch) files. Click About BOG then Customize BOG. Click on the box enabling the batch file option. BOG will no longer paste the long Gemray command directly into the DOS window. Rather, it will write a batch file (BOG.BAT), which contains the command, then issue "BOG.BAT" as a command to the DOS window. Try this option, since it may speed things considerably.
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Documentation maintained by Tom Herbst. Last modified 16-Aug-2005