Collision Detection for Identical Meshes and Open Curve Intersections

[Gihong-Yim]

I want to determine whether two meshes are colliding. However:

Boolean operations require the intersection to form a closed curve.
findCollidingTriangles does not seem to detect collisions when the same mesh is input.
getOneMeshIntersectionContours also seems to require the intersection to be a closed curve.
I have two questions:

How can I detect a collision when the two input meshes are identical?
How can I detect the intersection when the intersecting region does not form a closed curve?

[Grantim]

Hello!

Collision of identical meshes are not well defined, so it is a tricky question.

In boolean we use SoS(Simulation of Simplicity) that allows us to determine some intersection contours on identical meshes by changing them virtually based on topology.
You can get these intersections with this function:

MeshLib/source/MRMesh/MRMeshBoolean.h

Lines 98 to 99 in 3f13d6a

	/// returns intersection contours of given meshes
	MRMESH_API Contours3f findIntersectionContours( const Mesh& meshA, const Mesh& meshB, const AffineXf3f* rigidB2A = nullptr );

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How can I detect a collision when the two input meshes are identical?

You can consider it as all mesh or as none, based on your task

How can I detect the intersection when the intersecting region does not form a closed curve?

Closed curve is required to do boolean operation but you can still get intersection contour even if it is not closed.