Fix 5486

[NathanMOlson]

Fixes #5486.

Do not allow variable zoom tiles just because the top padding is non-zero. Only allow variable zoom at high pitch or when terrain is enabled.

• Briefly describe the changes in this PR.
• Link to related issues.
• Write tests for all new functionality.
• Add an entry to CHANGELOG.md under the ## main section.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.95%. Comparing base (a99fe93) to head (d959ece).
Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5518      +/-   ##
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- Coverage   91.96%   91.95%   -0.01%     
==========================================
  Files         282      282              
  Lines       39050    39050              
  Branches     6855     6853       -2     
==========================================
- Hits        35911    35909       -2     
- Misses       3012     3013       +1     
- Partials      127      128       +1     

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[HarelM]

Thanks! Do you think a render test can help here?

[NathanMOlson]

@HarelM No. The bug was in the way covering tiles were calculated when the top padding was non-zero. The new unit test covers that. The rendering problem shown in the original bug report was because the source did not contain the lower-zoom tiles that were being requested.

Current MapLibre behavior is not to request higher zoom tiles when the requested zoom is not available. This seems like a reasonable default to prevent an explosion of tile requests, but it may be worth looking into a way to change that behavior (outside the scope of this PR).

[HarelM]

In a render test we can have the numbers source and make sure all the tiles are from the same zoom, which is what this fix is about as far as I understand.
Before this fix there's a way to receive different zoom level, right?
This is just a thought, I'm fine with merging this as is too.

[NathanMOlson]

Before this fix there's a way to receive different zoom level, right?

Correct.

I think the existing unit test is more appropriate than a render test.