From 06b42de4c0111b88de319e57f388ad428d6b8bda Mon Sep 17 00:00:00 2001
From: Christophe Geuzaine <cgeuzaine@ulg.ac.be>
Date: Mon, 4 Oct 2010 11:37:23 +0000
Subject: [PATCH] fix orientation of STL mesh
---
Geo/OCCFace.cpp | 38 +++++++++++++++++++++++++++++++++++---
1 file changed, 35 insertions(+), 3 deletions(-)
diff --git a/Geo/OCCFace.cpp b/Geo/OCCFace.cpp
index f9619ef445..73320e06b5 100644
--- a/Geo/OCCFace.cpp
+++ b/Geo/OCCFace.cpp
@@ -366,13 +366,45 @@ bool OCCFace::buildSTLTriangulation(bool force)
stl_vertices.push_back(SPoint2(p.X(), p.Y()));
}
+ bool revert = false;
for(int i = 1; i <= triangulation->NbTriangles(); i++){
Poly_Triangle triangle = (triangulation->Triangles())(i);
int p1, p2, p3;
triangle.Get(p1, p2, p3);
- stl_triangles.push_back(p1 - 1);
- stl_triangles.push_back(p2 - 1);
- stl_triangles.push_back(p3 - 1);
+
+ // orient STL mesh to get normal right
+ if(i == 1){
+ gp_Pnt2d gp1 = (triangulation->UVNodes())(p1);
+ gp_Pnt2d gp2 = (triangulation->UVNodes())(p2);
+ gp_Pnt2d gp3 = (triangulation->UVNodes())(p3);
+ SPoint2 b = SPoint2(gp1.X(), gp1.Y()) + SPoint2(gp2.X(), gp2.Y()) +
+ SPoint2(gp3.X(), gp3.Y());
+ b *= 1. / 3.;
+ SVector3 nf = normal(b);
+ GPoint sp1 = point(gp1.X(), gp1.Y());
+ GPoint sp2 = point(gp2.X(), gp2.Y());
+ GPoint sp3 = point(gp3.X(), gp3.Y());
+ double n[3];
+ normal3points(sp1.x(), sp1.y(), sp1.z(),
+ sp2.x(), sp2.y(), sp2.z(),
+ sp3.x(), sp3.y(), sp3.z(), n);
+ SVector3 ne(n[0], n[1], n[2]);
+ if(dot(ne, nf) < 0){
+ Msg::Debug("Reverting orientation of STL mesh in face %d", tag());
+ revert = true;
+ }
+ }
+
+ if(!revert){
+ stl_triangles.push_back(p1 - 1);
+ stl_triangles.push_back(p2 - 1);
+ stl_triangles.push_back(p3 - 1);
+ }
+ else{
+ stl_triangles.push_back(p1 - 1);
+ stl_triangles.push_back(p3 - 1);
+ stl_triangles.push_back(p2 - 1);
+ }
}
return true;
--
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