Yet another NML questions thread.

[BobDendry]

Hi all

Yet another newbie NML coder here. I've experience with NFO, but NML is something that's completely foreign to me. However, I've decided to take it all in my stride and hop in and see what I can do with it.

The first wall I've hit is with the usage of articulated vehicles. In the same way I once used NFO to do this, I automatically started to write a switch block to define the different parts. This works fine, but the wiki says this is an old way to do callbacks and shouldn't be done unless one has a good reason. So I'm just wondering, how does one go about writing an articulated vehicle callback using the "new" style?

Thanks

Lachlan

[planetmaker]

The way FooBar layed it out in the tutorial: http://www.tt-wiki.net/wiki/NMLTutorial ... ticulation

[BobDendry]

okay, so this is the "new" way of doing it? For some reason, the documentation lead me to believe that it was something simple that went in the "graphics" section alone. I have done it in the right way, after all.

[Yexo]

The old way is this:

Code: Select all

switch(..., cb_articulated) {
...
}

switch (.., switch_cbs, callback_number) {
  VEH_CB_ARTICULATED_PARTS: cb_articulated;
  normal_graphics;
}

item {
  property {
    callbacks: bitmask(VEH_CBF_ARTICULATED_PARTS);
  }
  graphics {
    default: switch_cbs;
  }
}

The new way is this:

Code: Select all

switch(..., cb_articulated) {
...
}

item {
  graphics {
    articulated_parts: cb_articulated;
    default: normal_graphics;
  }
}

Basically you don't mess with callback numbers yourself but let nml handle that. This also means you can't forget to add a bit to the callback flags in your action0 (=property-block) anymore. Last but not least the code is smaller without losing clarity.

[planetmaker]

Well, the "new" way is to call the callbacks from the graphics section. In the simple cases you could return the value directly there (like if you only have one text, you might write

Code: Select all

graphics {
  additional_text: string(STR_EXTRA_VEHICLE_XXX_TEXT);
}

or in a case where you need to make a few decisions you link there to a switch dedicated to that callback:

Code: Select all

graphics {
  additional_text: decide_extra_text_vehicle_xxx;
}

or of course link to a certain switch section. The "new" thing about this is that the callback is not treated in the same switch tree as the graphics (real sprites, spritesets) are decided (as Yexo explained much more verbosely)

[Michi_cc]

Code: Select all

graphics {
  additional_text: string(STR_EXTRA_VEHICLE_XXX_TEXT);
}

That's missing a return, isn't it?

[Yexo]

Yes and No.

According to the specs there should be a return there, but for the compiler it's been optional for quite some time now. Please keep the return there, as in the future it might no longer be optional.