[CGAL Intersection Detection] PR Sofa and cgal intersection detection

[FadiWahbeh]

Based on #1

PR 01 — SOFA → CGAL Detection Bridge

Goal

This PR validates the first bridge between SOFA and CGAL inside MeshRepulsionEngine.

The component now:

• reads masterState, slaveState, masterTopology, and slaveTopology from SOFA;
• builds a CGAL::Surface_mesh from the SOFA master surface;
• builds a CGAL::Surface_mesh from the SOFA slave surface for validation/debug;
• uses CGAL::Side_of_triangle_mesh to classify slave vertices as:
  • inside the master mesh;
  • on the boundary of the master mesh;
  • outside the master mesh;
• prints diagnostic information in the terminal.

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Modify Test Scene

scenes/MeshRepulsion.scn

The scene uses the OBJ files at the paths defined in the MeshOBJLoader components.

Example:

<MeshOBJLoader name="loader" filename="./data/mesh/liver_coarse.obj"/>
<MeshOBJLoader name="loader" filename="./data/mesh/diaphragm.obj"/>

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Build

From the SOFA build environment, rebuild the plugin:

"/c/Program Files/CMake/bin/cmake.exe" --build /c/projects/sofa-build --config Release --target CGALPlugin

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Run

From the SOFA binary directory:

cd /c/projects/sofa-build/bin/Release 

./runSofa.exe /c/projects/sofa-plugins/CGALPlugin/scenes/MeshRepulsion_PR01.scn

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Expected Console Output

When the scene is loaded and/or when the simulation starts, the terminal should show a diagnostic line similar to:

[CGAL detection] step=1 masterVertices=600 masterTriangles=1200 slaveVertices=752 slaveTriangles=1500 inside=112 boundary=0 outside=640 slaveCgalFaces=1500

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What This PR Proves

This PR proves that:

• SOFA links are valid;
• CGAL can be called from inside MeshRepulsionEngine;
• the master obstacle can be converted from SOFA topology/positions to a CGAL surface mesh;
• the slave mesh can also be converted to a CGAL surface mesh for validation/debug;
• the current slave positions can be acquire from SOFA;
• slave vertices can be classified as inside, boundary, or outside the master mesh.

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Not Included Yet

This PR does not include:

• vertex displacement;
• face/edge/sphere collision detection;
• volumetric .msh slave handling;
• tetrahedral FEM scene;
• OBJ export.

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Next Step

The next PR will use the CGAL detection result to compute a small smooth displacement for slave vertices detected inside the master mesh.

The objective of PR 02 will be:

CGAL detects inside vertices → compute a small repulsion vector → update slave positions smoothly