[CURA-12446] Added settings for a different number of walls in top-/bottom-most skin.

[rburema]

See also front-end PR: Ultimaker/Cura#20565

[rburema]

• bridging not OK yet
• need to check if gradual sloping walls are OK (top AND bottom), like for example a sphere

[github-actions]

Test Results

28 tests  ±0   28 ✅ ±0   4s ⏱️ ±0s
 1 suites ±0    0 💤 ±0 
 1 files   ±0    0 ❌ ±0 

Results for commit 2c66ce4. ± Comparison against base commit 3afd632.

♻️ This comment has been updated with latest results.

[wawanbreton]

Just a few suggestions for readability, feel free to reject them

[rburema]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'C++ Benchmark'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.50.

Benchmark suite	Current: aed8b18	Previous: 945c507	Ratio
SimplifyTestFixture/simplify_slot_noplugin	1.8856092072748627 ns/iter	1.2446332009368046 ns/iter	1.51

This comment was automatically generated by workflow using github-action-benchmark.

CC: @nallath @jellespijker @wawanbreton @casperlamboo @saumyaj3 @HellAholic

[Copilot]

Pull Request Overview

This PR updates the engine's layer partitioning logic to support different wall settings on top‐ and bottom‐most skins. Key changes include:

• Enhancements to the createLayerWithParts function in src/layerPart.cpp to accept additional Shape parameters for bottom and top parts.
• Introduction of a new WallExposedType enum and updated wall count logic in WallsComputation.cpp to apply distinct wall settings.
• Updates in header files to reflect the new functionality and forward declarations.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/layerPart.cpp	Modified function signature and logic to split layers into multiple parts with wall-specific handling, plus new helper getTopOrBottom().
src/WallsComputation.cpp	Refactored wall count retrieval to use a mapping based on wall exposed type.
include/sliceDataStorage.h	Added the WallExposedType enum and a new member to track wall type on parts.
include/layerPart.h	Removed deprecated forward declarations and the old function signature declaration.

Comments suppressed due to low confidence (2)

src/layerPart.cpp:31

• [nitpick] Consider expanding the doc comment for createLayerWithParts to include descriptions for the newly added parameters (bottom_parts and top_parts) to improve clarity.

/*!

src/layerPart.cpp:117

• [nitpick] Consider replacing the hard-coded value '5' with a clearly named constant, which would improve readability and maintainability.

const auto wall_line_width = settings.get<coord_t>(layer_nr == 0 ? "wall_line_width_0" : "wall_line_width") - 5;

[rburema]

I'm not sure how well this'd work for values of 'extension' less than the wall-line-width -- but it's probably OK.