From 2763285b4620f61b6e4876fafc414a07a46dc741 Mon Sep 17 00:00:00 2001
From: Matthias Hochsteger <mhochsteger@cerbsim.com>
Date: Tue, 15 Sep 2020 15:48:49 +0200
Subject: [PATCH] csg2d - fix tutorial

---
 libsrc/geom2d/csg2d.cpp | 31 +++++++++++++++++++---
 py_tutorials/csg2d.py   | 57 ++++++++++++++++-------------------------
 2 files changed, 49 insertions(+), 39 deletions(-)

diff --git a/libsrc/geom2d/csg2d.cpp b/libsrc/geom2d/csg2d.cpp
index 0dddf074..e945c586 100644
--- a/libsrc/geom2d/csg2d.cpp
+++ b/libsrc/geom2d/csg2d.cpp
@@ -345,12 +345,35 @@ bool IsOverlapping( Spline p, Spline s, double & alpha, double & beta, Intersect
   // Check if s.p0 lies on p and vice versa, also check if tangents are in same direction (TODO: TEST)
   // If so, assume overlapping splines
   // TODO: Better checks! False positives could happen here!
-  IntersectSplineSegment1( p, s.StartPI(), p_mid, lam0, alpha, true );
-  IntersectSplineSegment1( s, p.StartPI(), s_mid, lam1, beta, true );
+  if(Dist(s.StartPI(), p.StartPI())<EPSILON)
+    {
+      lam0 = 0.0;
+      alpha = 0.0;
+    }
+  else if(Dist(s.StartPI(), p.EndPI())<EPSILON)
+    {
+      lam0 = 0.0;
+      alpha = 1.0;
+    }
+  else
+      IntersectSplineSegment1( p, s.StartPI(), p_mid, lam0, alpha, true );
+
+  if(Dist(p.StartPI(), s.StartPI())<EPSILON)
+    {
+      lam1 = 0.0;
+      beta = 0.0;
+    }
+  else if(Dist(p.StartPI(), s.EndPI())<EPSILON)
+    {
+      lam1 = 0.0;
+      beta = 1.0;
+    }
+  else
+      IntersectSplineSegment1( s, p.StartPI(), s_mid, lam1, beta, true );
 
   // Also check if midpoints lie on other spline
-  IntersectSplineSegment1( p, s.GetPoint(0.5), p_mid, lam2, alpha_mid, true );
-  IntersectSplineSegment1( s, p.GetPoint(0.5), s_mid, lam3, beta_mid, true );
+  IntersectSplineSegment1( p, s.GetPoint(0.4), p_mid, lam2, alpha_mid, true );
+  IntersectSplineSegment1( s, p.GetPoint(0.4), s_mid, lam3, beta_mid, true );
 
   auto tang0 = s.GetTangent(0.);
   auto tang1 = p.GetTangent(alpha);
diff --git a/py_tutorials/csg2d.py b/py_tutorials/csg2d.py
index 369101f3..f8050725 100644
--- a/py_tutorials/csg2d.py
+++ b/py_tutorials/csg2d.py
@@ -1,7 +1,5 @@
-from ngsolve import *
-
 from random import random, seed
-ngsglobals.msg_level = 0
+from ngsolve import Draw, Mesh
 
 import netgen
 from pyngcore import *
@@ -9,42 +7,31 @@ from netgen.geom2d import *
 
 seed(4)
 
-def GenerateMesh():
+g = CSG2d()
+outer = Rectangle((0, 0), (1, 1), "outer","outer")
+inner = Solid2d()
 
-    g = CSG2d()
-    g1 = CSG2d()
-    outer = Rectangle(0, 1, 0, 1,"outer","outer")
-    inner = Solid2d()
-
-    for i in range(30):
-        cx = random()
-        cy = random()
-        r  = 0.03+0.05*random()
-        print("Add Circle", i, cx, cy, r, flush = True)
-        circle = Circle(cx, cy, r, "circle"+str(i), "circle"+str(i))
-        g1.Add(circle)
-        inner += circle
-        outer -= circle
+for i in range(30):
+    cx = random()
+    cy = random()
+    r  = 0.03+0.05*random()
+    print("Add Circle", i, cx, cy, r, flush = True)
+    circle = Circle((cx, cy), r, "circle"+str(i), "circle"+str(i))
+    inner += circle
+    outer -= circle
 
 
-    g.Add(inner)
-    g.Add(outer)
-    geo = g.GenerateSplineGeometry()
+g.Add(inner)
+g.Add(outer)
+geo = g.GenerateSplineGeometry()
+
+m = geo.GenerateMesh(maxh=0.1)
+
+try:
+    from ngsolve import Draw, Mesh
     Draw(geo)
-
-    # draw this geometry for checking ff the final mesh/geometry is correct
-    # g1.Add(outer)
-    # geo1 = g1.GenerateSplineGeometry()
-    # Draw(geo1)
-
-    print('generate mesh')
-    m = geo.GenerateMesh(maxh=0.1)
     mesh = Mesh(m)
     mesh.Curve(3)
     Draw(mesh)
-
-    return mesh
-
-from ngsolve import Draw
-with PajeTrace():
-    mesh = GenerateMesh()
+except:
+    pass