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base repository: Project-SEA-Stack/SEA-Stack
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compare: salhus/linux-support-fixes
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  • 5 commits
  • 15 files changed
  • 1 contributor

Commits on Jun 10, 2026

  1. build(linux): prefer Chrono's bundled yaml-cpp and adapt to Chrono 10… 

    … API

Two small build fixes that together get SEA-Stack compiling cleanly on
Linux against Chrono 10.0.0.

* adapters/chrono/CMakeLists.txt — prefer Chrono::yaml-cpp over a
  system yaml-cpp when both are visible. Mixing Chrono's bundled
  yaml-cpp headers (from chrono_thirdparty/yaml-cpp/include) with
  a system libyaml-cpp.so triggers link errors against internal
  symbols such as YAML::FpToString and YAML::Emitter::Write.

* apps/seastack/single_run.cpp — Chrono 10 moved the protected
  m_script_directory member of ChParserMbsYAML into an internal file
  handler; the script directory must now be set via
  m_file_handler.SetReferenceDirectory(dir).
    Salman Husain committed Jun 10, 2026
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  2. fix(export): log joint reactions for all ChLink subclasses 

    The generic joint reaction extraction in SimulationExporter::RecordStep
was guarded by `dynamic_cast<ChLinkLock*>`, which silently fell through
to an "all zeros" fallback for every other ChLink subclass -- including
ChLinkUniversal (used by the 5SA articulated WEC demos), ChLinkRevolute,
ChLinkRevoluteSpherical, and others.

GetReaction1, GetReaction2, GetFrame1Abs, and GetFrame2Abs are virtual
on ChLinkBase, so they resolve uniformly for any concrete joint type.
Calling them on the base ChLink pointer fixes the export for all
current and future joint types.

Validation (5SA bimodal, 600s):
  Before:  joint_12..45  max |F| =       0.000 N for entire run
  After:   joint_12      max |F| =  192,471 N    max |T| =  158,075 N*m
           joint_23      max |F| =  211,687 N    max |T| =  220,279 N*m
           joint_34      max |F| =  201,941 N    max |T| =  311,303 N*m
           joint_45      max |F| =  169,830 N    max |T| =  401,657 N*m
  Internal consistency: reaction1_force == -reaction2_force to machine
  precision (Newton's third law).
    Salman Husain committed Jun 10, 2026
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  3. fix(5sa/bimodal): add heave/pitch/yaw damping and frequency-domain ex… 

    …citation

The bimodal case had linear_damping = [0, 100000, 0, 500000, 0, 0]
(zero linear damping in surge, heave, pitch, and yaw) and no quadratic
damping at all. The bimodal swell + wind-sea spectrum contains energy
near the chain's rigid-body heave natural frequency, and with no
restoring damping in heave the mode integrated unboundedly: at
t=198.86s body3 crossed 5 m/s, and by t=280s body z-positions exceeded
+10 m above SWL with the entire 144-m chain out of the water.

The fix mirrors the damping already present in the spreading case (a
near-identical multi-body configuration that runs to completion):

  linear_damping:    [20000, 80000, 80000, 500000, 200000, 200000]
  quadratic_damping: [10000, 40000, 40000, 250000, 100000, 100000]

It also adds an explicit `excitation: frequency_domain` block, again
mirroring spreading. The bimodal swell and wind-sea have different
headings, so excitation must be evaluated in the frequency domain --
this is auto-selected by the loader when wave components span multiple
headings, but stating it explicitly matches the parity with spreading
and makes intent clear.

Validation (run_seastack 600s, no MoorDyn):
  Before: body3 max |v| = diverged past 5.0 m/s at t=198.86s
          body3 max z   = +10.98 m at t=280s (chain in the air)
          run terminated at 280.7s
  After:  body3 max |v| = 3.92 m/s at t=592.99s (bounded)
          body3 max z   = within +/- 2 m throughout
          run completed full 600s, clean exit, 2m wallclock
    Salman Husain committed Jun 10, 2026
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  4. fix(gui/vsg): use opaque water surface to avoid runtime DepthSorted c… 

    …rash

When the animated water surface is added to the VSG scene graph after
ChVisualSystemVSG::Initialize() -- which happens because the wave model
is set up at runtime, not pre-bind -- Chrono's wrapIfTransparent helper
wraps the new node in a vsg::DepthSorted set to bin 10 if the material
opacity is less than 1.0. The first record traversal that encounters
this node then segfaults inside vsg::Bin::add() because the bin and
its pipeline state were not present when Initialize() finalized the
view's render path.

Stack at the crash:
  #0  vsg::Bin::add(State*, double, Node const*)
  #1  vsg::RecordTraversal::apply(MatrixTransform const&)
  #2  vsg::Group::traverse(RecordTraversal&)
   ...
  #N  chrono::vsg3d::ChVisualSystemVSG::Render()

Water surface (kWaterOpacity=0.55) and wireframe overlay
(SetOpacity(0.35)) both hit this. Setting both to 1.0 keeps the nodes
out of the bin-10 DepthSorted path, so neither demos nor run_seastack
crash on first render, including with the in-GUI wireframe toggle.

Tradeoff: the water is opaque so submerged geometry is no longer
visible through it. The proper fix is to compile any runtime-added
transparent subtree against the live viewer (Chrono's ChShapeBuilderVSG
owns an m_compileTraversal for this purpose but it is not exposed via
SEA-Stack's public API surface). Tracking as a follow-up.
    Salman Husain committed Jun 10, 2026
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  5. chore(scripts): mark unix shell scripts as executable 

    Each script under scripts/unix/ was checked in with mode 100644 (no
executable bit), so `./scripts/unix/build.sh` fails on a fresh Linux
clone. Setting +x on all of them makes the standard invocation pattern
work as documented.
    Salman Husain committed Jun 10, 2026
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