From c90c4291b87087c3a8de72df68e7190deedbb6f2 Mon Sep 17 00:00:00 2001
From: Christoph Lehmann <christoph.lehmann@ufz.de>
Date: Mon, 25 Apr 2022 08:31:20 +0200
Subject: [PATCH] [MeL] Surface normal computation also for lines
---
MeshLib/Elements/Utils.h | 49 ++++++++++++++++++++++++++++++----------
1 file changed, 37 insertions(+), 12 deletions(-)
diff --git a/MeshLib/Elements/Utils.h b/MeshLib/Elements/Utils.h
index 6fa00f580cb..f4eb2d25c4c 100644
--- a/MeshLib/Elements/Utils.h
+++ b/MeshLib/Elements/Utils.h
@@ -46,19 +46,44 @@ inline Eigen::Vector3d calculateNormalizedSurfaceNormal(
MeshLib::Element const& bulk_element)
{
Eigen::Vector3d surface_element_normal;
- if (surface_element.getDimension() < 2)
- {
- auto const bulk_element_normal =
- MeshLib::FaceRule::getSurfaceNormal(bulk_element);
- auto const& v0 = surface_element.getNode(0)->asEigenVector3d();
- auto const& v1 = surface_element.getNode(1)->asEigenVector3d();
- Eigen::Vector3d const edge_vector = v1 - v0;
- surface_element_normal = bulk_element_normal.cross(edge_vector);
- }
- else
+
+ switch (surface_element.getDimension())
{
- surface_element_normal =
- MeshLib::FaceRule::getSurfaceNormal(surface_element);
+ case 2:
+ surface_element_normal =
+ MeshLib::FaceRule::getSurfaceNormal(surface_element);
+ break;
+ case 1:
+ {
+ auto const bulk_element_normal =
+ MeshLib::FaceRule::getSurfaceNormal(bulk_element);
+ auto const& v0 = surface_element.getNode(0)->asEigenVector3d();
+ auto const& v1 = surface_element.getNode(1)->asEigenVector3d();
+ Eigen::Vector3d const edge_vector = v1 - v0;
+ surface_element_normal = -bulk_element_normal.cross(edge_vector);
+ break;
+ }
+ case 0:
+ {
+ assert(surface_element.getCellType() == CellType::POINT1);
+ assert(bulk_element.getCellType() == CellType::LINE2 ||
+ bulk_element.getCellType() == CellType::LINE3);
+
+ auto const& x = surface_element.getNode(0)->asEigenVector3d();
+
+ // The start of the line element.
+ auto const& a = bulk_element.getNode(0)->asEigenVector3d();
+
+ // The end of the line element is the 2nd base node of the line,
+ // which is the 2nd node.
+ auto const& b = bulk_element.getNode(1)->asEigenVector3d();
+
+ // x coincides either with the start or with the end of the line.
+ // a + b - 2 * x evaluates to a - b or to b - a, respectively.
+ // The formula assumes that the line is perfectly straight, even in
+ // the LINE3 case.
+ surface_element_normal = a + b - 2 * x;
+ }
}
surface_element_normal.normalize();
--
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