//
// Visualz
//
//Show triangles
private void ShowTriangles(HalfEdgeData2 triangles)
{
controller.ResetMultiColoredMeshes();
List <Mesh> meshes = controller.GenerateTriangulationMesh(triangles, shouldUnNormalize: true);
List <Material> materials = controller.GenerateRandomMaterials(meshes.Count);
controller.multiColoredMeshes = meshes;
controller.multiColoredMeshesMaterials = materials;
}
//
// Display stuff
//
//Show points
private void ShowPoints(HashSet <MyVector2> points)
{
controller.ResetBlackMeshes();
HashSet <Triangle2> triangles = new HashSet <Triangle2>();
foreach (MyVector2 p in points)
{
MyVector2 point = controller.UnNormalize(p);
HashSet <Triangle2> circleTriangles = _GenerateMesh.Circle(point, 0.1f, 10);
triangles.UnionWith(circleTriangles);
}
//Will unnormalize
List <Mesh> meshes = controller.GenerateTriangulationMesh(triangles, shouldUnNormalize: false);
controller.blackMeshes = meshes;
}
//
// For visualization when pressing Play button
//
private void Start()
{
GenerateTriangulation();
//To access standardized methods for visualizations
VisualizerController visualizerController = GetComponent <VisualizerController>();
//Generate the meshes and materials once
meshes = visualizerController.GenerateTriangulationMesh(triangulation, shouldUnNormalize: false);
materials = visualizerController.GenerateRandomMaterials(meshes.Count);
StartCoroutine(DisplayTriangleByTriangle(meshes));
}
public void StartVisualizer(HashSet <MyVector2> points, HalfEdgeData2 triangleData)
{
controller = GetComponent <VisualizerController>();
//Step 1. Triangulate the points with some algorithm. The result is a convex triangulation
HashSet <Triangle2> triangles = _TriangulatePoints.VisibleEdgesTriangulation(points);
//HashSet<Triangle2> triangles = _TriangulatePoints.TriangleSplitting(points);
//Step 2. Change the data structure from triangle to half-edge to make it easier to flip edges
triangleData = _TransformBetweenDataStructures.Triangle2ToHalfEdge2(triangles, triangleData);
//Generate the visual triangles
controller.GenerateTriangulationMesh(triangleData);
//Step 3. Flip edges until we have a delaunay triangulation
StartCoroutine(FlipEdges(triangleData));
}
//
// Visualize stuff
//
private void ShowAllPoints(HashSet <MyVector2> points)
{
HashSet <Triangle2> triangles = new HashSet <Triangle2>();
foreach (MyVector2 p in points)
{
HashSet <Triangle2> tCircle = _GenerateMesh.Circle(controller.UnNormalize(p), 0.1f, 10);
triangles.UnionWith(tCircle);
}
//To mesh
List <Mesh> meshes = controller.GenerateTriangulationMesh(triangles, shouldUnNormalize: false);
controller.ResetBlackMeshes();
controller.blackMeshes = meshes;
//Debug.Log(meshes.Count);
}
//Flip edges until we get a delaunay triangulation
private IEnumerator FlipEdges(HalfEdgeData2 triangleData)
{
//The edges we want to flip
HashSet <HalfEdge2> edges = triangleData.edges;
//To avoid getting stuck in infinite loop
int safety = 0;
//Count how many edges we have flipped, which may be interesting to display
int flippedEdges = 0;
while (true)
{
safety += 1;
if (safety > 100000)
{
Debug.Log("Stuck in endless loop when flipping edges to get a Delaunay triangulation");
break;
}
bool hasFlippedEdge = false;
//Search through all edges to see if we can flip an edge
foreach (HalfEdge2 thisEdge in edges)
{
//Is this edge sharing an edge with another triangle, otherwise its a border, and then we cant flip the edge
if (thisEdge.oppositeEdge == null)
{
continue;
}
//The positions of the vertices belonging to the two triangles that we might flip
//a-c should be the edge that we might flip
MyVector2 a = thisEdge.v.position;
MyVector2 b = thisEdge.nextEdge.v.position;
MyVector2 c = thisEdge.nextEdge.nextEdge.v.position;
MyVector2 d = thisEdge.oppositeEdge.nextEdge.v.position;
//If we want to display the test circle
//controller.GenerateDelaunayCircleMeshes(a, b, c, d);
//yield return new WaitForSeconds(controller.pauseTime);
//Test if we should flip this edge
if (DelaunayMethods.ShouldFlipEdge(a, b, c, d))
{
flippedEdges += 1;
hasFlippedEdge = true;
HalfEdgeHelpMethods.FlipTriangleEdge(thisEdge);
controller.flipText.text = "Flipped edges: " + flippedEdges;
controller.GenerateTriangulationMesh(triangleData);
yield return(new WaitForSeconds(controller.pauseTime));
}
}
//We have searched through all edges and havent found an edge to flip, so we have a Delaunay triangulation!
if (!hasFlippedEdge)
{
Debug.Log("Found a delaunay triangulation in " + flippedEdges + " flips");
break;
}
}
//Remove the circle meshes so we see that we are finished
controller.ClearBlackMeshes();
yield return(null);
}
private IEnumerator RunVisualization(HashSet <MyVector2> points)
{
//Step 0. Init the triangles we will return
HashSet <Triangle2> triangles = new HashSet <Triangle2>();
//Step 1. Sort the points
List <MyVector2> sortedPoints = new List <MyVector2>(points);
//OrderBy is always soring in ascending order - use OrderByDescending to get in the other order
//sortedPoints = sortedPoints.OrderBy(n => n.x).ToList();
//If we have colinear points we have to sort in both x and y
sortedPoints = sortedPoints.OrderBy(n => n.x).ThenBy(n => n.y).ToList();
//Step 2. Create the first triangle so we can start the algorithm because we need edges to look at
//and see if they are visible
//Pick the first two points in the sorted list - These are always a part of the first triangle
MyVector2 p1 = sortedPoints[0];
MyVector2 p2 = sortedPoints[1];
//Remove them
sortedPoints.RemoveAt(0);
sortedPoints.RemoveAt(0);
//The problem is the third point
//If we have colinear points, then the third point in the sorted list is not always a valid point
//to form a triangle because then it will be flat
//So we have to look for a better point
for (int i = 0; i < sortedPoints.Count; i++)
{
//We have found a non-colinear point
LeftOnRight pointRelation = Geometry.IsPoint_Left_On_Right_OfVector(p1, p2, sortedPoints[i]);
if (pointRelation == LeftOnRight.Left || pointRelation == LeftOnRight.Right)
{
MyVector2 p3 = sortedPoints[i];
//Remove this point
sortedPoints.RemoveAt(i);
//Build the first triangle
Triangle2 newTriangle = new Triangle2(p1, p2, p3);
triangles.Add(newTriangle);
break;
}
}
////If we have finished search and not found a triangle, that means that all points
////are colinear and we cant form any triangles
//if (triangles.Count == 0)
//{
// Debug.Log("All points you want to triangulate a co-linear");
// return null;
//}
//Show the triangulation
controller.GenerateTriangulationMesh(triangles);
yield return(new WaitForSeconds(controller.pauseTime));
//Step 3. Add the other points one-by-one
//For each point we add we have to calculate a convex hull of the previous points
//An optimization is to not use all points in the triangulation
//to calculate the hull because many of them might be inside of the hull
//So we will use the previous points on the hull and add the point we added last iteration
//to generate the new convex hull
//First we need to init the convex hull
HashSet <MyVector2> triangulatePoints = new HashSet <MyVector2>();
foreach (Triangle2 t in triangles)
{
triangulatePoints.Add(t.p1);
triangulatePoints.Add(t.p2);
triangulatePoints.Add(t.p3);
}
//Calculate the first convex hull
List <MyVector2> pointsOnHull = _ConvexHull.JarvisMarch(triangulatePoints);
//Add the other points one-by-one
foreach (MyVector2 pointToAdd in sortedPoints)
{
bool couldFormTriangle = false;
controller.SetActivePoint(pointToAdd);
//Loop through all edges in the convex hull
for (int j = 0; j < pointsOnHull.Count; j++)
{
MyVector2 hull_p1 = pointsOnHull[j];
MyVector2 hull_p2 = pointsOnHull[MathUtility.ClampListIndex(j + 1, pointsOnHull.Count)];
//First we have to check if the points are colinear, then we cant form a triangle
LeftOnRight pointRelation = Geometry.IsPoint_Left_On_Right_OfVector(hull_p1, hull_p2, pointToAdd);
if (pointRelation == LeftOnRight.On)
{
continue;
}
//If this triangle is clockwise, then we can see the edge
//so we should create a new triangle with this edge and the point
if (Geometry.IsTriangleOrientedClockwise(hull_p1, hull_p2, pointToAdd))
{
triangles.Add(new Triangle2(hull_p1, hull_p2, pointToAdd));
couldFormTriangle = true;
//Show the triangulation
controller.GenerateTriangulationMesh(triangles);
yield return(new WaitForSeconds(controller.pauseTime));
}
}
//Add the point to the list of points on the hull
//Will re-generate the hull by using these points so dont worry that the
//list is not valid anymore
if (couldFormTriangle)
{
pointsOnHull.Add(pointToAdd);
//Find the convex hull of the current triangulation
//It generates a counter-clockwise convex hull
pointsOnHull = _ConvexHull.JarvisMarch(new HashSet <MyVector2>(pointsOnHull));
}
else
{
Debug.Log("This point could not form any triangles " + pointToAdd.x + " " + pointToAdd.y);
}
}
yield return(null);
}
IEnumerator InsertPoints(HashSet <MyVector2> points, HalfEdgeData2 triangulationData, Triangle2 superTriangle)
{
//Visualize the first triangle
controller.GenerateTriangulationMesh(triangulationData);
yield return(new WaitForSeconds(controller.pauseTime));
//Step 4. Loop over each point we want to insert and do Steps 5-7
//These are for display purposes only
int missedPoints = 0;
int flippedEdges = 0;
foreach (MyVector2 p in points)
{
//Step 5. Insert the new point in the triangulation
//Find the existing triangle the point is in
HalfEdgeFace2 f = PointTriangulationIntersection.TriangulationWalk(p, null, triangulationData);
//We couldnt find a triangle maybe because the point is not in the triangulation?
if (f == null)
{
missedPoints += 1;
}
//Delete this triangle and form 3 new triangles by connecting p to each of the vertices in the old triangle
HalfEdgeHelpMethods.SplitTriangleFaceAtPoint(f, p, triangulationData);
//Visualize
//Display the point as a black circle
controller.GenerateCircleMesh(p, shouldResetAllMeshes: true);
yield return(new WaitForSeconds(controller.pauseTime));
controller.GenerateTriangulationMesh(triangulationData);
yield return(new WaitForSeconds(controller.pauseTime));
//Step 6. Initialize stack. Place all triangles which are adjacent to the edges opposite p on a LIFO stack
//The report says we should place triangles, but it's easier to place edges with our data structure
Stack <HalfEdge2> trianglesToInvestigate = new Stack <HalfEdge2>();
AddTrianglesOppositePToStack(p, trianglesToInvestigate, triangulationData);
//Step 7. Restore delaunay triangulation
//While the stack is not empty
int safety = 0;
while (trianglesToInvestigate.Count > 0)
{
safety += 1;
if (safety > 1000000)
{
Debug.Log("Stuck in infinite loop when restoring delaunay in incremental sloan algorithm");
break;
}
//Step 7.1. Remove a triangle from the stack
HalfEdge2 edgeToTest = trianglesToInvestigate.Pop();
//Step 7.2. Do we need to flip this edge?
//If p is outside or on the circumcircle for this triangle, we have a delaunay triangle and can return to next loop
MyVector2 a = edgeToTest.v.position;
MyVector2 b = edgeToTest.prevEdge.v.position;
MyVector2 c = edgeToTest.nextEdge.v.position;
//abc are here counter-clockwise
if (DelaunayMethods.ShouldFlipEdgeStable(a, b, c, p))
{
HalfEdgeHelpMethods.FlipTriangleEdge(edgeToTest);
//Step 7.3. Place any triangles which are now opposite p on the stack
AddTrianglesOppositePToStack(p, trianglesToInvestigate, triangulationData);
flippedEdges += 1;
//Visualize
controller.flipText.text = "Flipped edges: " + flippedEdges;
controller.GenerateTriangulationMesh(triangulationData);
yield return(new WaitForSeconds(controller.pauseTime));
}
}
}
controller.ClearBlackMeshes();
//Step 8. Delete the vertices belonging to the supertriangle
StartCoroutine(RemoveSuperTriangle(superTriangle, triangulationData));
yield return(null);
}
