Merge pull request #22 from pierre-dejoue/master

Add documentation and code patches for maintenability

CMakeLists.txt

@@ -7,7 +7,8 @@ option(P2T_BUILD_TESTS "Build tests" OFF)
 option(P2T_BUILD_TESTBED "Build the testbed application" OFF)
 
 file(GLOB SOURCES poly2tri/common/*.cc poly2tri/sweep/*.cc)
-add_library(poly2tri ${SOURCES})
+file(GLOB HEADERS poly2tri/*.h poly2tri/common/*.h poly2tri/sweep/*.h)
+add_library(poly2tri ${SOURCES} ${HEADERS})
 target_include_directories(poly2tri INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
 
 if(P2T_BUILD_TESTS)

README.md

@@ -52,6 +52,8 @@ python waf configure
 python waf build
 ```
 
+Alternatively, the testbed can be built using cmake. See below.
+
 Running the Examples
 --------------------
 
@@ -59,7 +61,7 @@ Load data points from a file:
 ```
 p2t <filename> <center_x> <center_y> <zoom>
 ```
-Random distribution of points inside a consrained box:
+Random distribution of points inside a constrained box:
 ```
 p2t random <num_points> <box_radius> <zoom>
 ```
@@ -71,3 +73,42 @@ Examples:
 ./build/p2t random 10 100 5.0
 ./build/p2t random 1000 20000 0.025
 ```
+
+BUILD WITH CMAKE
+================
+
+Build the library
+-----------------
+
+```
+mkdir build && cd build
+cmake -GNinja
+cmake --build .
+```
+
+Build and run the unit tests
+----------------------------
+
+```
+mkdir build && cd build
+cmake -GNinja -DP2T_BUILD_TESTS=ON
+cmake --build .
+ctest --output-on-failure
+```
+
+Build the testbed
+-----------------
+
+```
+mkdir build && cd build
+cmake -GNinja -DP2T_BUILD_TESTBED=ON
+cmake --build .
+```
+
+References
+==========
+
+- Domiter V. and Zalik B. (2008) Sweep‐line algorithm for constrained Delaunay triangulation
+- FlipScan by library author Thomas Åhlén
+
+![FlipScan](doc/FlipScan.png)

poly2tri/common/shapes.cc

@@ -243,6 +243,17 @@ Point* Triangle::PointCCW(const Point& point)
   return nullptr;
 }
 
+// The neighbor across to given point
+Triangle* Triangle::NeighborAcross(const Point& point)
+{
+  if (&point == points_[0]) {
+    return neighbors_[0];
+  } else if (&point == points_[1]) {
+    return neighbors_[1];
+  }
+  return neighbors_[2];
+}
+
 // The neighbor clockwise to given point
 Triangle* Triangle::NeighborCW(const Point& point)
 {
@@ -349,23 +360,6 @@ void Triangle::SetDelunayEdgeCW(const Point& p, bool e)
   }
 }
 
-// The neighbor across to given point
-Triangle& Triangle::NeighborAcross(const Point& opoint)
-{
-  Triangle* neighbor = nullptr;
-  if (&opoint == points_[0]) {
-    neighbor = neighbors_[0];
-  } else if (&opoint == points_[1]) {
-    neighbor = neighbors_[1];
-  } else {
-    neighbor = neighbors_[2];
-  }
-  if (neighbor == nullptr) {
-      throw std::runtime_error("NeighborAcross - null neighbor");
-  }
-  return *neighbor;
-}
-
 void Triangle::DebugPrint()
 {
   std::cout << *points_[0] << " " << *points_[1] << " " << *points_[2] << std::endl;

poly2tri/common/shapes.h

@@ -176,6 +176,7 @@ void MarkConstrainedEdge(Point* p, Point* q);
 int Index(const Point* p);
 int EdgeIndex(const Point* p1, const Point* p2);
 
+Triangle* NeighborAcross(const Point& point);
 Triangle* NeighborCW(const Point& point);
 Triangle* NeighborCCW(const Point& point);
 bool GetConstrainedEdgeCCW(const Point& p);
@@ -203,8 +204,6 @@ void ClearDelunayEdges();
 inline bool IsInterior();
 inline void IsInterior(bool b);
 
-Triangle& NeighborAcross(const Point& opoint);
-
 void DebugPrint();
 
 bool CircumcicleContains(const Point&) const;

poly2tri/sweep/sweep.cc

@@ -108,6 +108,9 @@ void Sweep::EdgeEvent(SweepContext& tcx, Edge* edge, Node* node)
 
 void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangle, Point& point)
 {
+  if (triangle == nullptr) {
+    throw std::runtime_error("EdgeEvent - null triangle");
+  }
   if (IsEdgeSideOfTriangle(*triangle, ep, eq)) {
     return;
   }
@@ -120,7 +123,7 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
       // We are modifying the constraint maybe it would be better to
       // not change the given constraint and just keep a variable for the new constraint
       tcx.edge_event.constrained_edge->q = p1;
-      triangle = &triangle->NeighborAcross(point);
+      triangle = triangle->NeighborAcross(point);
       EdgeEvent(tcx, ep, *p1, triangle, *p1);
     } else {
       throw std::runtime_error("EdgeEvent - collinear points not supported");
@@ -136,7 +139,7 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
       // We are modifying the constraint maybe it would be better to
       // not change the given constraint and just keep a variable for the new constraint
       tcx.edge_event.constrained_edge->q = p2;
-      triangle = &triangle->NeighborAcross(point);
+      triangle = triangle->NeighborAcross(point);
       EdgeEvent(tcx, ep, *p2, triangle, *p2);
     } else {
       throw std::runtime_error("EdgeEvent - collinear points not supported");
@@ -155,6 +158,7 @@ void Sweep::EdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* triangl
     EdgeEvent(tcx, ep, eq, triangle, point);
   } else {
     // This triangle crosses constraint so lets flippin start!
+    assert(triangle);
     FlipEdgeEvent(tcx, ep, eq, triangle, point);
   }
 }
@@ -215,7 +219,6 @@ void Sweep::Fill(SweepContext& tcx, Node& node)
   if (!Legalize(tcx, *triangle)) {
     tcx.MapTriangleToNodes(*triangle);
   }
-
 }
 
 void Sweep::FillAdvancingFront(SweepContext& tcx, Node& n)
@@ -610,7 +613,6 @@ void Sweep::FillRightConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
       }
     }
   }
-
 }
 
 void Sweep::FillRightConvexEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
@@ -691,12 +693,17 @@ void Sweep::FillLeftConcaveEdgeEvent(SweepContext& tcx, Edge* edge, Node& node)
       }
     }
   }
-
 }
 
 void Sweep::FlipEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle* t, Point& p)
 {
-  Triangle& ot = t->NeighborAcross(p);
+  assert(t);
+  Triangle* ot_ptr = t->NeighborAcross(p);
+  if (ot_ptr == nullptr)
+  {
+    throw std::runtime_error("FlipEdgeEvent - null neighbor across");
+  }
+  Triangle& ot = *ot_ptr;
   Point& op = *ot.OppositePoint(*t, p);
 
   if (InScanArea(p, *t->PointCCW(p), *t->PointCW(p), op)) {
@@ -762,7 +769,11 @@ Point& Sweep::NextFlipPoint(Point& ep, Point& eq, Triangle& ot, Point& op)
 void Sweep::FlipScanEdgeEvent(SweepContext& tcx, Point& ep, Point& eq, Triangle& flip_triangle,
                               Triangle& t, Point& p)
 {
-  Triangle& ot = t.NeighborAcross(p);
+  Triangle* ot_ptr = t.NeighborAcross(p);
+  if (ot_ptr == nullptr) {
+    throw std::runtime_error("FlipScanEdgeEvent - null neighbor across");
+  }
+  Triangle& ot = *ot_ptr;
   Point& op = *ot.OppositePoint(t, p);
 
   if (InScanArea(eq, *flip_triangle.PointCCW(eq), *flip_triangle.PointCW(eq), op)) {
@@ -790,5 +801,4 @@ Sweep::~Sweep() {
 
 }
 
-}
-
+} // namespace p2t

poly2tri/sweep/sweep.h

@@ -33,7 +33,7 @@
  * Zalik, B.(2008)'Sweep-line algorithm for constrained Delaunay triangulation',
  * International Journal of Geographical Information Science
  *
- * "FlipScan" Constrained Edge Algorithm invented by Thomas ?hl?n, thahlen@gmail.com
+ * "FlipScan" Constrained Edge Algorithm invented by Thomas Åhlén, thahlen@gmail.com
  */
 
 #ifndef SWEEP_H

poly2tri/sweep/sweep_context.cc

@@ -87,8 +87,8 @@ void SweepContext::InitTriangulation()
 
   double dx = kAlpha * (xmax - xmin);
   double dy = kAlpha * (ymax - ymin);
-  head_ = new Point(xmax + dx, ymin - dy);
-  tail_ = new Point(xmin - dx, ymin - dy);
+  head_ = new Point(xmin - dx, ymin - dy);
+  tail_ = new Point(xmax + dx, ymin - dy);
 
   // Sort points along y-axis
   std::sort(points_.begin(), points_.end(), cmp);
@@ -124,7 +124,7 @@ void SweepContext::CreateAdvancingFront()
 {
 
   // Initial triangle
-  Triangle* triangle = new Triangle(*points_[0], *tail_, *head_);
+  Triangle* triangle = new Triangle(*points_[0], *head_, *tail_);
 
   map_.push_back(triangle);
 

testbed/main.cc

@@ -28,18 +28,22 @@
  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-#include <cstdlib>
-#include <GLFW/glfw3.h>
-#include <time.h>
-#include <fstream>
-#include <string>
-#include <sstream>
-#include <algorithm>
-#include <iterator>
-#include <iostream>
-using namespace std;
+#include <poly2tri/poly2tri.h>
 
-#include "../poly2tri/poly2tri.h"
+#include <GLFW/glfw3.h>
+
+#include <algorithm>
+#include <cstdlib>
+#include <ctime>
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <list>
+#include <sstream>
+#include <string>
+#include <vector>
+
+using namespace std;
 using namespace p2t;
 
 void Init();

unittest/main.cpp

@@ -3,9 +3,11 @@
 #endif
 #define BOOST_TEST_MODULE Poly2triTest
 
+#include <poly2tri/poly2tri.h>
+
 #include <boost/filesystem/path.hpp>
 #include <boost/test/unit_test.hpp>
-#include <poly2tri/poly2tri.h>
+
 #include <fstream>
 #include <iostream>
 #include <iterator>
@@ -19,7 +21,7 @@ BOOST_AUTO_TEST_CASE(BasicTest)
     new p2t::Point(1, 1),
   };
   p2t::CDT cdt{ polyline };
-  cdt.Triangulate();
+  BOOST_CHECK_NO_THROW(cdt.Triangulate());
   const auto result = cdt.GetTriangles();
   BOOST_REQUIRE_EQUAL(result.size(), 1);
   BOOST_CHECK_EQUAL(*result[0]->GetPoint(0), *polyline[0]);
@@ -36,7 +38,7 @@ BOOST_AUTO_TEST_CASE(QuadTest)
   std::vector<p2t::Point*> polyline{ new p2t::Point(0, 0), new p2t::Point(0, 1),
                                      new p2t::Point(1, 1), new p2t::Point(1, 0) };
   p2t::CDT cdt{ polyline };
-  cdt.Triangulate();
+  BOOST_CHECK_NO_THROW(cdt.Triangulate());
   const auto result = cdt.GetTriangles();
   BOOST_REQUIRE_EQUAL(result.size(), 2);
   BOOST_CHECK(p2t::IsDelaunay(result));
@@ -45,7 +47,7 @@ BOOST_AUTO_TEST_CASE(QuadTest)
   }
 }
 
-BOOST_AUTO_TEST_CASE(QuadTestThrow)
+BOOST_AUTO_TEST_CASE(NarrowQuadTest)
 {
   // Very narrow quad that demonstrates a failure case during triangulation
   std::vector<p2t::Point*> polyline {
@@ -90,7 +92,7 @@ BOOST_AUTO_TEST_CASE(TestbedFilesTest)
       polyline.push_back(new p2t::Point(x, y));
     }
     p2t::CDT cdt{ polyline };
-    cdt.Triangulate();
+    BOOST_CHECK_NO_THROW(cdt.Triangulate());
     const auto result = cdt.GetTriangles();
     BOOST_REQUIRE(result.size() * 3 > polyline.size());
     BOOST_CHECK_MESSAGE(p2t::IsDelaunay(result), filename + std::to_string(polyline.size()));