If you want to actively contribute to the development of OpenTTD, you will need to debug your patch. Use your favourite debugger for debugging. In addition to that, OpenTTD has some debugger options that might help you.
If you just downloaded the game and something does not work, you also might to run the game with debugging enabled.
Starting the game with "-d 1" will enable global debug level '1'. All debug messages with a severity of 1 will be shown. Use the following syntax in a command line window:
user@home\> openttd -d 1
In addition to that, you can only show debug messages for certain areas of the game. Currently there are 3 such items:
|misc||Will show messages for miscellaneous events. This includes loading of sound, video, or resorting of various items or general warning messages||1, 2|
|spritecache||Will show the processing of sprites||1, 2 and 9|
|grf||Will show Newgrf messages, such as their copyright info (1) and notices if some parts failed to load, were loaded incorrectly, or are not yet supported (2)||1, 2|
You can combine any of these to get only their desired lvl. For example misc 1 and grf 1:
user@home\> openttd -d misc=1 grf=1
Debug messages with lvl 0 will always be shown, unless you remove these debugs. To strip the executable of any debug messages, compile with the flag: