- Fixed: A splitter that cannot properly divide a seg into two pieces because it is too close

to an endpoint to produce a unique vertex must be rejected.



SVN r2090 (trunk)

nodebuild.cpp

@@ -32,7 +32,7 @@
 #define Printf printf
 #define STACK_ARGS
 
-#if 1
+#if 0
 #define D(x) x
 #else
 #define D(x) do{}while(0)
@@ -499,8 +499,8 @@ int FNodeBuilder::SelectSplitter (DWORD set, node_t &node, DWORD &splitseg, int
 
 int FNodeBuilder::Heuristic (node_t &node, DWORD set, bool honorNoSplit)
 {
-	// Set the initial score above 0 so that near vertex anti-weighting does not automatically disqualify the vertex.
-	int score = 100000000;
+	// Set the initial score above 0 so that near vertex anti-weighting is less likely to produce a negative score.
+	int score = 1000000;
 	int segsInSet = 0;
 	int counts[2] = { 0, 0 };
 	int realSegs[2] = { 0, 0 };
@@ -605,17 +605,30 @@ int FNodeBuilder::Heuristic (node_t &node, DWORD set, bool honorNoSplit)
 
 			// Splitters that are too close to a vertex are bad.
 			frac = InterceptVector (node, *test);
-			if (frac < 0.001)
+			if (frac < 0.001 || frac > 0.999)
 			{
+				FPrivVert *v1 = &Vertices[test->v1];
+				FPrivVert *v2 = &Vertices[test->v2];
+				double x = v1->x, y = v1->y;
+				x += frac * (v2->x - x);
+				y += frac * (v2->y - y);
+				if (fabs(x - v1->x) < VERTEX_EPSILON+1 && fabs(y - v1->y) < VERTEX_EPSILON+1)
+				{
+					D(Printf("Splitter will produce same start vertex as seg %d\n", i));
+					return -1;
+				}
+				if (fabs(x - v2->x) < VERTEX_EPSILON+1 && fabs(y - v2->y) < VERTEX_EPSILON+1)
+				{
+					D(Printf("Splitter will produce same end vertex as seg %d\n", i));
+					return -1;
+				}
+				if (frac > 0.999)
+				{
+					frac = 1 - frac;
+				}
 				int penalty = int(1 / frac);
 				score = MAX(score - penalty, 1);
-				D(Printf ("Penalized splitter by %d for being too close to start vertex of seg %d.\n", penalty, i));
-			}
-			else if (frac > 0.999)
-			{
-				int penalty = int(1 / (1 - frac));
-				score = MAX(score - penalty, 1);
-				D(Printf ("Penalized splitter by %d for being too close to end vertex of seg %d.\n", penalty, i));
+				D(Printf ("Penalized splitter by %d for being near endpt of seg %d (%f).\n", penalty, i, frac));
 			}
 
 			counts[0]++;
@@ -790,6 +803,28 @@ void FNodeBuilder::SplitSegs (DWORD set, node_t &node, DWORD splitseg, DWORD &ou
 			newvert.index = 0;
 			vertnum = VertexMap->SelectVertexClose (newvert);
 
+			if (vertnum == seg->v1 || vertnum == seg->v2)
+			{
+				Printf("SelectVertexClose selected endpoint of seg %u\n", set);
+				// Check if the resulting split vertex matches one of the line's ends.
+				// In this case this seg must not be split
+				if ((vertnum == seg->v1 && sidev2 == -1) || (vertnum == seg->v2 && sidev1 == -1))
+				{
+					side = 0;
+					sidev1 = 0;
+					seg->next = outset0;
+					outset0 = set;
+				}
+				else
+				{
+					side = 1;
+					sidev2 = 0;
+					seg->next = outset1;
+					outset1 = set;
+				}
+				break;
+			}
+
 			seg2 = SplitSeg (set, vertnum, sidev1);
 
 			Segs[seg2].next = outset0;

nodebuild.h

@@ -250,6 +250,9 @@ private:
 // Units are in fixed_ts.
 const double SIDE_EPSILON = 6.5536;
 
+// Vertices within this distance of each other will be considered as the same vertex.
+#define VERTEX_EPSILON	6		// This is a fixed_t value
+
 inline int FNodeBuilder::PointOnSide (int x, int y, int x1, int y1, int dx, int dy)
 {
 	// For most cases, a simple dot product is enough.

nodebuild_utility.cpp

@@ -28,10 +28,6 @@
 static const int PO_LINE_START = 1;
 static const int PO_LINE_EXPLICIT = 5;
 
-// Vertices within this distance of each other vertically and horizontally
-// will be considered as the same vertex.
-const fixed_t VERTEX_EPSILON = 6;
-
 #if 0
 #define D(x) x
 #else
@@ -503,8 +499,12 @@ int FNodeBuilder::FVertexMap::SelectVertexClose (FNodeBuilder::FPrivVert &vert)
 
 	for (i = 0; i < block.Size(); ++i)
 	{
+#if VERTEX_EPSILON <= 1
+		if (vertices[block[i]].x == vert.x && vertices[block[i]].y == vert.y)
+#else
 		if (abs(vertices[block[i]].x - vert.x) < VERTEX_EPSILON &&
 			abs(vertices[block[i]].y - vert.y) < VERTEX_EPSILON)
+#endif
 		{
 			return block[i];
 		}