gp_Vec normalToFaceAtUV(const TopoDS_Face& face, double u, double v)
{
BRepLProp_SLProps localSurfaceProps(1, 1e-6);
localSurfaceProps.SetSurface(BRepAdaptor_Surface(face));
localSurfaceProps.SetParameters(u, v);
if (localSurfaceProps.IsNormalDefined()) {
const gp_Dir& nc = localSurfaceProps.Normal();
if (face.Orientation() == TopAbs_REVERSED)
return gp_Vec(-nc.X(), -nc.Y(), -nc.Z());
else
return gp_Vec(nc.X(), nc.Y(), nc.Z());
}
return gp_Vec(0., 0., 1.);
//return normalToSurfaceAtUV(BRep_Tool::Surface(face), u, v);
}
void BuildShapeMesh(osg::Geode *geode, const TopoDS_Shape &shape, const osg::Vec4 &color, double deflection)
{
bool bSetNormal = true;
osg::ref_ptr<deprecated_osg::Geometry> triGeom = new deprecated_osg::Geometry();
osg::ref_ptr<osg::Vec3Array> theVertices = new osg::Vec3Array();
osg::ref_ptr<osg::Vec3Array> theNormals = new osg::Vec3Array();
BRepMesh::Mesh(shape, deflection);
TopExp_Explorer faceExplorer;
for (faceExplorer.Init(shape, TopAbs_FACE); faceExplorer.More(); faceExplorer.Next())
{
TopLoc_Location theLocation;
TopoDS_Face theFace = TopoDS::Face(faceExplorer.Current());
if (theFace.IsNull())
continue;
const Handle_Poly_Triangulation &theTriangulation = BRep_Tool::Triangulation(theFace, theLocation);
BRepLProp_SLProps theProp(BRepAdaptor_Surface(theFace), 1, Precision::Confusion());
Standard_Integer nTriangles = theTriangulation->NbTriangles();
for (Standard_Integer i = 1; i <= nTriangles; i++)
{
const Poly_Triangle& theTriangle = theTriangulation->Triangles().Value(i);
gp_Pnt theVertex1 = theTriangulation->Nodes().Value(theTriangle(1));
gp_Pnt theVertex2 = theTriangulation->Nodes().Value(theTriangle(2));
gp_Pnt theVertex3 = theTriangulation->Nodes().Value(theTriangle(3));
const gp_Pnt2d &theUV1 = theTriangulation->UVNodes().Value(theTriangle(1));
const gp_Pnt2d &theUV2 = theTriangulation->UVNodes().Value(theTriangle(2));
const gp_Pnt2d &theUV3 = theTriangulation->UVNodes().Value(theTriangle(3));
theVertex1.Transform(theLocation.Transformation());
theVertex2.Transform(theLocation.Transformation());
theVertex3.Transform(theLocation.Transformation());
// find the normal for the triangle mesh.
gp_Vec V12(theVertex1, theVertex2);
gp_Vec V13(theVertex1, theVertex3);
gp_Vec theNormal = V12 ^ V13;
gp_Vec theNormal1 = theNormal;
gp_Vec theNormal2 = theNormal;
gp_Vec theNormal3 = theNormal;
if (theNormal.Magnitude() > Precision::Confusion())
{
theNormal.Normalize();
theNormal1.Normalize();
theNormal2.Normalize();
theNormal3.Normalize();
}
theProp.SetParameters(theUV1.X(), theUV1.Y());
if (theProp.IsNormalDefined())
{
theNormal1 = theProp.Normal();
}
theProp.SetParameters(theUV2.X(), theUV2.Y());
if (theProp.IsNormalDefined())
{
theNormal2 = theProp.Normal();
}
theProp.SetParameters(theUV3.X(), theUV3.Y());
if (theProp.IsNormalDefined())
{
theNormal3 = theProp.Normal();
}
if (theFace.Orientation() == TopAbs_REVERSED)
{
theNormal.Reverse();
theNormal1.Reverse();
theNormal2.Reverse();
theNormal3.Reverse();
}
theVertices->push_back(osg::Vec3(theVertex1.X(), theVertex1.Y(), theVertex1.Z()));
theVertices->push_back(osg::Vec3(theVertex2.X(), theVertex2.Y(), theVertex2.Z()));
theVertices->push_back(osg::Vec3(theVertex3.X(), theVertex3.Y(), theVertex3.Z()));
if (bSetNormal)
{
theNormals->push_back(osg::Vec3(theNormal1.X(), theNormal1.Y(), theNormal1.Z()));
theNormals->push_back(osg::Vec3(theNormal2.X(), theNormal2.Y(), theNormal2.Z()));
theNormals->push_back(osg::Vec3(theNormal3.X(), theNormal3.Y(), theNormal3.Z()));
}
else
{
theNormals->push_back(osg::Vec3(theNormal.X(), theNormal.Y(), theNormal.Z()));
theNormals->push_back(osg::Vec3(theNormal.X(), theNormal.Y(), theNormal.Z()));
theNormals->push_back(osg::Vec3(theNormal.X(), theNormal.Y(), theNormal.Z()));
}
}
}
triGeom->setVertexArray(theVertices.get());
triGeom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::TRIANGLES, 0, theVertices->size()));
triGeom->setNormalArray(theNormals);
triGeom->setNormalBinding(deprecated_osg::Geometry::BIND_PER_VERTEX);
osg::ref_ptr<osg::Vec4Array> colArr = new osg::Vec4Array();
colArr->push_back(color);
triGeom->setColorArray(colArr, osg::Array::BIND_OVERALL);
geode->addDrawable(triGeom);
}