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Fix weirdness of new stations. #10017

Merged
merged 3 commits into from Sep 11, 2022
Merged

Fix weirdness of new stations. #10017

merged 3 commits into from Sep 11, 2022

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frosch123
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Motivation / Problem

I just wanted to document NML stations a bit, but got lost in weird corners cases of NML and OpenTTD.

Description

  • Callback 14 has some bugs in the GUI (but not on map)
    • Result bit 0 is supposed to be ignored and replaced with the orientation, but instead the orientaion was just added.
    • Var10 contains no data for callback 14. The GUI code passed the value intended for callback 24.
  • If stations defined exactly one sprite layout, both in-GUI and on-map drawing code would out-of-bounds access a vector.
    • This PR enforces an even number of spritelayouts when loading the NewGRF.
    • It does this by dropping the last layout. That way any NewGRF using an odd number of layouts is now equally broken for X and Y direction.

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

  • The bug fix is important enough to be backported? (label: 'backport requested')
  • This PR touches english.txt or translations? Check the guidelines
  • This PR affects the save game format? (label 'savegame upgrade')
  • This PR affects the GS/AI API? (label 'needs review: Script API')
    • ai_changelog.hpp, gs_changelog.hpp need updating.
    • The compatibility wrappers (compat_*.nut) need updating.
  • This PR affects the NewGRF API? (label 'needs review: NewGRF')

@frosch123
Cleanup: [NewGRF] Callback 14 used a weird value for var10 in the GUI.
c537a67 
The value 0x2110000 probably originated from a mixup between callback 14 (sprite layout) and 24 (tile layout).
The latter does indeed use a var10 value like that.
@frosch123
Fix: [NewGRF] Result bit 0 of callback 14 was not ignored in the GUI.
7ec7043
@frosch123
Fix: [NewGRF] Ensure that stations always have an even number of spri…
d646467 
…te layouts.

The drawing code has a special fallbacks for zero layouts, but fails hard for one layout.
(odd numbers >= 3 are weird, but do not fail as badly as 1)
@frosch123 frosch123 merged commit e2c46fd into OpenTTD:master Sep 11, 2022
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@glx22 glx22 glx22 approved these changes

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@frosch123 @glx22