private void AddEdge(int v0, int v1, float cost)
{
// remove all edges crossing our clipping edge (TODO: could we split them instead?)
Edge clippingEdge = new Edge(v0, v1, cost);
Stack <Edge> candidates = new Stack <Edge>();
candidates.Push(clippingEdge);
while (candidates.Count > 0)
{
Edge cEdge = candidates.Pop();
bool isect = false;
if ((vertices[cEdge.v[0]] - vertices[cEdge.v[1]]).Length() > 1e-3f)
{
foreach (Edge e in edges)
{
Vertex p;
if (e.v[0] != cEdge.v[0] && e.v[0] != cEdge.v[1] &&
e.v[1] != cEdge.v[0] && e.v[1] != cEdge.v[1] &&
GeomUtils.SegmentIntersect(vertices[e.v[0]], vertices[e.v[1]], vertices[cEdge.v[0]], vertices[cEdge.v[1]], out p))
{
vertices.Add(p);
int isectIdx = vertices.Count - 1;
edges.Remove(e);
edges.Add(new Edge(e.v[0], isectIdx, e.cost));
edges.Add(new Edge(isectIdx, e.v[1], e.cost));
candidates.Push(new Edge(cEdge.v[0], isectIdx, cost));
candidates.Push(new Edge(isectIdx, cEdge.v[1], cost));
isect = true;
break;
}
}
if (!isect)
{
edges.Add(cEdge);
}
}
}
}
public bool FlipTriangles(int tri1, int tri2, out int[] result)
{
Triangle triangle1 = triangles[tri1];
Debug.Assert(triangle1.valid);
Triangle triangle2 = triangles[tri2];
Debug.Assert(triangle2.valid);
int commonEdgeIdx = CommonEdge(triangle1, triangle2);
Debug.Assert(commonEdgeIdx >= 0);
Edge commonEdge = edges[commonEdgeIdx];
Debug.Assert(commonEdge.triangles[0] == tri1 || commonEdge.triangles[0] == tri2);
Debug.Assert(commonEdge.triangles[1] == tri1 || commonEdge.triangles[1] == tri2);
// Tri1 = A,B,C
// Tri2 = B,D,C
// commonEdge = B,C
int localEdgeT1 = triangle1.LocalEdgeIndex(commonEdgeIdx);
Debug.Assert(localEdgeT1 >= 0);
int localEdgeT2 = triangle2.LocalEdgeIndex(commonEdgeIdx);
Debug.Assert(localEdgeT2 >= 0);
int A = VertexOutOfTriEdge(tri1, localEdgeT1);
int D = VertexOutOfTriEdge(tri2, localEdgeT2);
Debug.Assert(A >= 0);
Debug.Assert(D >= 0);
int B = (commonEdge.triangles[0] == tri1 ? commonEdge.vertices[0] : commonEdge.vertices[1]);
int C = (B == commonEdge.vertices[0] ? commonEdge.vertices[1] : commonEdge.vertices[0]);
Debug.Assert(A != B && A != C && A != D && B != C && B != D && C != D);
result = new int[2];
if (!GeomUtils.SegmentIntersect(vertices[A], vertices[D], vertices[B], vertices[C]))
{
// can't flip
result[0] = result[1] = -1;
return(false);
}
float closestAngleBefore = Math.Min(ClosestAngleOnTri(A, B, C), ClosestAngleOnTri(B, D, C));
if (!IsWorthFlipping(A, B, C, D))
{
// The resulting triangles would not improve the triangulation, don't bother
return(false);
}
RemoveTriangle(tri1);
RemoveTriangle(tri2);
result[0] = CreateTriangle(A, B, D);
result[1] = CreateTriangle(A, D, C);
float closestAngleAfter = Math.Min(ClosestAngleOnTri(A, B, D), ClosestAngleOnTri(A, D, C));
//Debug.Assert(closestAngleBefore < closestAngleAfter);
#if DEBUG
Debug.Assert(CheckConsistency());
#endif
return(true);
}
private static void MergeTiles(List <PoissonSample> source, List <PoissonSample> toMerge,
neighbour_e side,
out List <PoissonSample> result)
{
List <MergeCandidate> candidates = new List <MergeCandidate>();
foreach (PoissonSample s in source)
{
candidates.Add(new MergeCandidate(s, 0));
}
foreach (PoissonSample s in toMerge)
{
candidates.Add(new MergeCandidate(s, 1));
}
const float scale = 1000.0f; // apply a temporary scaling to the Poisson points (in 0-1 range)
// before Delaunay triangulation (we'll undo this later) to avoid
// requiring very small epsilons for point snapping etc which
// may lead to numeric issues.
List <Vertex> vertices = new List <Vertex>();
for (int i = 0; i < candidates.Count; i++)
{
vertices.Add(new Vertex(candidates[i].sample.x * scale, candidates[i].sample.y * scale));
}
List <int> outTriangles;
Adjacency adjacency = new Adjacency();
Delaunay2D.Delaunay2DTriangulate(vertices, false, out outTriangles, ref adjacency);
for (int j = 0; j < adjacency.vertices.Count; j++)
{
adjacency.vertices[j].x /= scale;
adjacency.vertices[j].y /= scale;
}
Image debugImage = null;
if (OnDebugStep != null)
{
debugImage = new Bitmap(800, 800);
}
Voronoi v = Voronoi.FromDelaunay(adjacency);
#if DEBUG
if (debugImage != null)
{
v.ToImage(debugImage, adjacency);
OnDebugStep(debugImage, "Voronoi diagram generated from Delaunay Triangulation");
}
#endif
Graph g = new Graph(v, adjacency, candidates);
if (debugImage != null)
{
g.ToImage(debugImage);
OnDebugStep(debugImage, "Merging " + NeighbourName(side) + " tile: Convert voronoi diagram into a graph");
}
int v0, v1;
for (int i = 0; i < 4; i++)
{
if (i != (int)side)
{
g.Clip((WangTile.neighbour_e)i, out v0, out v1);
}
}
g.Clip(side, out v0, out v1);
#if DEBUG
if (debugImage != null)
{
g.ToImage(debugImage);
OnDebugStep(debugImage, "Graph generated from Voronoi Diagram");
}
#endif
List <int> path;
g.ShortestPath(v0, v1, out path);
List <Vertex> shape;
g.GenerateShape(path, out shape);
for (int i = 0; i < shape.Count - 1; i++) // skip last one as it is the same as the first element (they're references)
{
shape[i].x *= scale;
shape[i].y *= scale;
}
if (debugImage != null)
{
Graphics grph = Graphics.FromImage(debugImage);
Pen sp = new Pen(Color.Orange, 2);
for (int i = 0; i < shape.Count - 1; i++)
{
grph.DrawLine(sp,
shape[i].x / scale * debugImage.Width,
shape[i].y / scale * debugImage.Height,
shape[i + 1].x / scale * debugImage.Width,
shape[i + 1].y / scale * debugImage.Height);
}
OnDebugStep(debugImage, "Merging " + NeighbourName(side) + " tile: Orange line displays the lowest cost seam");
}
result = new List <PoissonSample>();
for (int i = 0; i < candidates.Count; i++)
{
bool insideSeam = GeomUtils.PointInPolygon(new Vertex(candidates[i].sample.x * scale, candidates[i].sample.y * scale), shape);
if ((insideSeam && candidates[i].sourceDist == 1) ||
(!insideSeam && candidates[i].sourceDist == 0))
{
result.Add(candidates[i].sample);
}
}
if (debugImage != null)
{
Graphics grph = Graphics.FromImage(debugImage);
grph.Clear(Color.White);
SolidBrush brushInside = new SolidBrush(Color.Red);
SolidBrush brushOutside = new SolidBrush(Color.Gray);
for (int i = 0; i < result.Count; i++)
{
bool insideSeam = GeomUtils.PointInPolygon(new Vertex(result[i].x * scale, result[i].y * scale), shape);
float r = (float)debugImage.Width * 0.01f;
RectangleF rect = new RectangleF(result[i].x * debugImage.Width - r, result[i].y * debugImage.Height - r, 2.0f * r, 2.0f * r);
if (insideSeam)
{
grph.FillEllipse(brushInside, rect);
}
else
{
grph.FillEllipse(brushOutside, rect);
}
}
OnDebugStep(debugImage, "Merging " + NeighbourName(side) + " tile: gray dots = base tile, red dots = merged points");
}
}