new grf coding/adjusting?

[SniperDJ]

hello everybody,

are there any clear guide or tutorials on adjusting newgrfs (road vehicle ones)?

because I would really like to adjust some road sets (with permission of course) to fix compatibility with new industries.

[Supercheese]

AFAIK, there are no guides for editing existing GRFs via decompiling and recompiling, as that results in uncommented NFO, which is a real pain in the ass to read. However, if you're lucky enough to have the source available, then you should just be able to follow existing tutorials, but simply starting with what already exists and moving from there.

[Alberth]

I'd first try to write a new newgrf that performs the fix. At least for the default vehicles that can be done, and perhaps for the non-standard ones it can be done as well.

[frosch]

Maybe instead of editing the GRF it is easier to write an add-on GRF.

1) Get grf2html and use it to figure out the vehicle IDs the target GRF uses: http://www.tt-forums.net/viewtopic.php?f=68&t=34279
2) Write your own GRF, e,g. with NML: http://www.tt-wiki.net/wiki/NMLTutorial
2.1) Define you GRF as add-on to the target GRF: http://newgrf-specs.tt-wiki.net/wiki/NM ... er_NewGRFs
2.2) Assign new values to the refitting properties: http://newgrf-specs.tt-wiki.net/wiki/NML:Vehicles

[FooBar]

For example code for such an add-on, you can take a look at the Dutch Trainset Cargo Extension: http://www.tt-forums.net/viewtopic.php?t=55872
Source code is provided in the download of the first post.
With only minor adjustments you can modify that to work with a different vehicle set, it's pretty straightforward. And in this case you don't need permission of the original set's author, as you're not modifying that. My code is GPL'ed, so as long as you respect that license you can do whatever you want with it.

If you want to fix an existing set with permission, you might as well ask for the source code when asking for permission.

[SniperDJ]

thank you for all your quick replies

i'll check them all out and see what i can do with them

thanks in advance