Recast: move surface area quantization into its own function

Avoid potential mistakes in the future by using the wrong quant factor.

src/thirdparty/recast/Detour/Include/DetourNavMesh.h

@@ -273,6 +273,7 @@ struct dtPoly
 ///  @param[in]		verts	The polygon vertices.
 /// @return The total surface are of the polygon.
 float dtCalcPolySurfaceArea(const dtPoly* poly, const float* verts);
+unsigned short dtQuantPolySurfaceArea(const float area);
 
 /// Defines the location of detail sub-mesh data within a dtMeshTile.
 struct dtPolyDetail

src/thirdparty/recast/Detour/Source/DetourNavMesh.cpp

@@ -1865,7 +1865,7 @@ float dtCalcLinkDistance(const float* spos, const float* epos)
 unsigned char dtQuantLinkDistance(const float distance)
 {
 	if (distance > DT_TRAVERSE_DIST_MAX) return (unsigned char)0;
-	return (unsigned char)(distance * DT_TRAVERSE_DIST_QUANT_FACTOR);
+	return (unsigned char)(rdMathRoundf(distance * DT_TRAVERSE_DIST_QUANT_FACTOR));
 }
 
 float dtCalcPolySurfaceArea(const dtPoly* poly, const float* verts)
@@ -1885,6 +1885,11 @@ float dtCalcPolySurfaceArea(const dtPoly* poly, const float* verts)
 	return polyArea;
 }
 
+unsigned short dtQuantPolySurfaceArea(const float area)
+{
+	return (unsigned short)rdMathRoundf(area * DT_POLY_AREA_QUANT_FACTOR);
+}
+
 float dtCalcOffMeshRefYaw(const float* spos, const float* epos)
 {
 	const float dx = epos[0]-spos[0];

src/thirdparty/recast/Detour/Source/DetourNavMeshBuilder.cpp

@@ -1050,7 +1050,7 @@ bool dtCreateNavMeshData(dtNavMeshCreateParams* params, unsigned char** outData,
 			p->vertCount++;
 		}
 		rdVscale(p->center, p->center, 1 / (float)(p->vertCount));
-		p->surfaceArea = (unsigned short)rdMathFloorf(dtCalcPolySurfaceArea(p,navVerts) * DT_POLY_AREA_QUANT_FACTOR);
+		p->surfaceArea = dtQuantPolySurfaceArea(dtCalcPolySurfaceArea(p,navVerts));
 
 		src += nvp*2;
 	}