From 29db8cde1bf323e6f828db3b70a754a3025e9076 Mon Sep 17 00:00:00 2001
From: Mikko Mononen <memon@inside.org>
Date: Sun, 19 Jan 2014 17:49:40 +0200
Subject: [PATCH] Fix for detail mesh corner cases

- fix case where thing long poly center may not be on the region
---
 Recast/Source/RecastMeshDetail.cpp | 115 +++++++++++++----------------
 1 file changed, 53 insertions(+), 62 deletions(-)

diff --git a/Recast/Source/RecastMeshDetail.cpp b/Recast/Source/RecastMeshDetail.cpp
index 3b94663..69ed147 100644
--- a/Recast/Source/RecastMeshDetail.cpp
+++ b/Recast/Source/RecastMeshDetail.cpp
@@ -751,64 +751,55 @@ static void getHeightData(const rcCompactHeightfield& chf,
 	// since border size offset is already removed from the polymesh vertices.
 
 	stack.resize(0);
-
-	static const int offset[9*2] =
-	{
-		0,0, -1,0, 0,1, 1,0, 0,-1, -1,-1, -1,1, 1,1, 1,-1
-	};
-
-	// find the center of the polygon
-	int pcx = 0, pcz = 0;
-	for (int j = 0; j < npoly; ++j)
-	{
-		pcx += (int)verts[poly[j]*3+0];
-		pcz += (int)verts[poly[j]*3+2];
-	}
-	pcx /= npoly;
-	pcz /= npoly;
-
-	// find a span with the right region around this point
-	// No need to check for connectivity because the region ensures it
-	for (int dir = 0; dir < 9; ++dir)
-	{
-		int ax = pcx + offset[dir*2+0];
-		int az = pcz + offset[dir*2+1];
-
-		if (ax < hp.xmin || ax >= hp.xmin+hp.width ||
-			az < hp.ymin || az >= hp.ymin+hp.height)
-			continue;
-
-		const rcCompactCell& c = chf.cells[(ax+bs)+(az+bs)*chf.width];
-		for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
-		{
-			const rcCompactSpan& s = chf.spans[i];
-			if (s.reg == region)
-			{
-				stack.push(ax);
-				stack.push(az);
-				stack.push(i);
-				break;
-			}
-		}
-		if (stack.size() > 0)
-			break;
-	}
-
-	// Floodfill the heightfield to get 2D height data,
-	// starting at center location found above as seed.
-
 	memset(hp.data, 0xff, sizeof(unsigned short)*hp.width*hp.height);
 
-	// Mark start locations.
-	for (int i = 0; i < stack.size(); i += 3)
+	// Copy the height from the same region, and mark region borders
+	// as seed points to fill the rest.
+	for (int hy = 0; hy < hp.height; hy++)
 	{
-		int cx = stack[i+0];
-		int cy = stack[i+1];
-		int ci = stack[i+2];
-		int idx = cx-hp.xmin+(cy-hp.ymin)*hp.width;
-		const rcCompactSpan& cs = chf.spans[ci];
-		hp.data[idx] = cs.y;
-	}
+		int y = hp.ymin + hy + bs;
+		for (int hx = 0; hx < hp.width; hx++)
+		{
+			int x = hp.xmin + hx + bs;
+			const rcCompactCell& c = chf.cells[x+y*chf.width];
+			for (int i = (int)c.index, ni = (int)(c.index+c.count); i < ni; ++i)
+			{
+				const rcCompactSpan& s = chf.spans[i];
+				if (s.reg == region)
+				{
+					// Store height
+					hp.data[hx + hy*hp.width] = s.y;
+
+					// If any of the neighbours is not in same region,
+					// add the current location as flood fill start
+					bool border = false;
+					for (int dir = 0; dir < 4; ++dir)
+					{
+						if (rcGetCon(s, dir) != RC_NOT_CONNECTED)
+						{
+							const int ax = x + rcGetDirOffsetX(dir);
+							const int ay = y + rcGetDirOffsetY(dir);
+							const int ai = (int)chf.cells[ax+ay*chf.width].index + rcGetCon(s, dir);
+							const rcCompactSpan& as = chf.spans[ai];
+							if (as.reg != region)
+							{
+								border = true;
+								break;
+							}
+						}
+					}
+					if (border)
+					{
+						stack.push(x);
+						stack.push(y);
+						stack.push(i);
+					}
+					break;
+				}
+			}
+		}
+	}	
+
 	
 	static const int RETRACT_SIZE = 256;
 	int head = 0;
@@ -834,19 +825,19 @@ static void getHeightData(const rcCompactHeightfield& chf,
 			
 			const int ax = cx + rcGetDirOffsetX(dir);
 			const int ay = cy + rcGetDirOffsetY(dir);
+			const int hx = ax - hp.xmin - bs;
+			const int hy = ay - hp.ymin - bs;
 			
-			if (ax < hp.xmin || ax >= (hp.xmin+hp.width) ||
-				ay < hp.ymin || ay >= (hp.ymin+hp.height))
+			if (hx < 0 || hx >= hp.width || hy < 0 || hy >= hp.height)
 				continue;
 			
-			if (hp.data[ax-hp.xmin+(ay-hp.ymin)*hp.width] != RC_UNSET_HEIGHT)
+			if (hp.data[hx + hy*hp.width] != RC_UNSET_HEIGHT)
 				continue;
 			
-			const int ai = (int)chf.cells[(ax+bs)+(ay+bs)*chf.width].index + rcGetCon(cs, dir);
-			
+			const int ai = (int)chf.cells[ax + ay*chf.width].index + rcGetCon(cs, dir);
 			const rcCompactSpan& as = chf.spans[ai];
-			int idx = ax-hp.xmin+(ay-hp.ymin)*hp.width;
-			hp.data[idx] = as.y;
+
+			hp.data[hx + hy*hp.width] = as.y;
 
 			stack.push(ax);
 			stack.push(ay);