Cargo_capacity and "N/A" line in the train info window

[TadeuszD]

A few months (years?) ago I encountered small problem with cargo capacity information displayed in the train information window.
Example #1:
Articulated vehicle, all parts have the same ID, no refit option, only first part of vehicle can transport cargo:

Code: Select all

switch(FEAT_TRAINS, SELF, switch_v1_capacity, position_in_vehid_chain%2) {
    0: return 48;
    return 0;
}

In this example OTTD displays correct capacity in the train window.

Example #2:
Vehicle from example #1, but cargo_subtype refit options are defined:

Code: Select all

switch(FEAT_TRAINS, SELF, switch_v2_capacity, position_in_vehid_chain%2) {
    0: return 48;
    return 0;
}
switch(FEAT_TRAINS, SELF, switch_v2_subtype_text, cargo_subtype) {
    0: return string(STR_SUBTYPE_1);
    1: return string(STR_SUBTYPE_2);
    return CB_RESULT_NO_TEXT;
}

In this example OTTD displays strange additional line in the train info window, such as:

Code: Select all

empty
N/A

I don't understand why OTTD displays "N/A" depending on the refit option is on or off...
Typically, I use workaround to prevent displaying "N/A". You should leave at least 1 cargo unit in second part to do it:

Code: Select all

switch(FEAT_TRAINS, SELF, switch_v2_capacity, position_in_vehid_chain) {
    0: return 48-1;
    return 1;
}

It works, but it looks like a tricky "hack" and has impact on loading speed...

But yesterday I tested the new example - articulated vehicle containing a few parts with different IDs and different cargo classes. Additionaly, cargo_subtype refit options are defined for this vehicle.
In this example the information displayed in the train info window looks totally unpredictable...
Where can I find the rules of collecting and displaying such information in train window?

[Transportman]

What happens when you try to use the PARENT scope for the subtypes instead of SELF?

Also, on all your code examples, you would get unwanted behavior with multiple sets behind each other as you don't use a modulus (%) in your switch expression. Instead of Engine-Articulated-Engine-Articulated it would behave as Engine-Articulated-Articulated-Articulated for everything you use that switch block for.

[TadeuszD]

What happens when you try to use the PARENT scope for the subtypes instead of SELF?.

I think, it is not good idea. I'm working with data of current vehicle, not the leading engine. And my problem is not caused by incorrect behavior of the vehicle or its visual glitches.
Simply put, I don't understand why OTTD displays this unexpected "N/A" line in the list of transported cargo? Maybe this is the simple rule, but I don't see it...

...you don't use a modulus (%) in your switch expression.

Thanks. Of course, I use '%' in my original code. Unfortunately, I have deleted this sign during simplifying the example code... Corrected.

[frosch]

Maybe it's a bug in OpenTTD

Can you post the GRF which causes the two lines "empty N/A" to FlySpray?