shadow for unclosed shape

[yoogera]

hi, i create a cloth scene node in irrlicht. i want to show its shadow(addShadowVolumeSceneNode), found that in irrlicht only generate back face node's shadow.
CShadowVolumeSceneNode.cpp line 122

#ifdef IRR_USE_REVERSE_EXTRUDED
FaceData=core::triangle3df(v0,v1,v2).isFrontFacing(light);
#else
FaceData=core::triangle3df(v2,v1,v0).isFrontFacing(light);
#endif

if (UseZFailMethod && FaceData)

it check FaceData to generate shadow, but front face not.
if the node is a closed shape, it is nothing, but if it is a unclosed shape, some shadows lost, can any one help me？thk

[mongoose7]

Irrlicht only generates shadows for the triangles facing the light. This has nothing to do with front-facing and back-facing. But note that the decision depends on the "winding" of the vertices.