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[Upstream] Make detail mesh edge detection more robust (recastnavigation #657) 

- https://github.com/recastnavigation/recastnavigation/pull/657

Instead of using a distance check which can fail at large magnitudes due
to low precision we can check whether the edges are actually on the
hull.
This commit is contained in:
ikpil 2023-12-22 22:20:45 +09:00 committed by Ikpil
parent a3f426b186
commit 6474f234a3
1 changed files with 39 additions and 30 deletions
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69
src/DotRecast.Recast/RcMeshDetails.cs
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@ -982,6 +982,7 @@ namespace DotRecast.Recast
if (minExtent < sampleDist * 2)
{
TriangulateHull(nverts, verts, nhull, hull, nin, tris);
SetTriFlags(tris, nhull, hull);
return nverts;
}
@ -1101,13 +1102,48 @@ namespace DotRecast.Recast
List<int> subList = tris.GetRange(0, MAX_TRIS * 4);
tris.Clear();
tris.AddRange(subList);
throw new Exception(
"rcBuildPolyMeshDetail: Shrinking triangle count from " + ntris + " to max " + MAX_TRIS);
throw new Exception("rcBuildPolyMeshDetail: Shrinking triangle count from " + ntris + " to max " + MAX_TRIS);
}
SetTriFlags(tris, nhull, hull);
return nverts;
}
static bool OnHull(int a, int b, int nhull, int[] hull)
{
// All internal sampled points come after the hull so we can early out for those.
if (a >= nhull || b >= nhull)
return false;
for (int j = nhull - 1, i = 0; i < nhull; j = i++)
{
if (a == hull[j] && b == hull[i])
return true;
}
return false;
}
// Find edges that lie on hull and mark them as such.
static void SetTriFlags(List<int> tris, int nhull, int[] hull)
{
// Matches DT_DETAIL_EDGE_BOUNDARY
const int DETAIL_EDGE_BOUNDARY = 0x1;
for (int i = 0; i < tris.Count; i += 4)
{
int a = tris[i];
int b = tris[i + 1];
int c = tris[i + 2];
int flags = 0;
flags |= (OnHull(a, b, nhull, hull) ? DETAIL_EDGE_BOUNDARY : 0) << 0;
flags |= (OnHull(b, c, nhull, hull) ? DETAIL_EDGE_BOUNDARY : 0) << 2;
flags |= (OnHull(c, a, nhull, hull) ? DETAIL_EDGE_BOUNDARY : 0) << 4;
tris[i + 3] = flags;
}
}
static void SeedArrayWithPolyCenter(RcTelemetry ctx, RcCompactHeightfield chf, int[] meshpoly, int poly, int npoly,
int[] verts, int bs, RcHeightPatch hp, List<int> array)
{
@ -1387,32 +1423,6 @@ namespace DotRecast.Recast
}
}
static int GetEdgeFlags(float[] verts, int va, int vb, float[] vpoly, int npoly)
{
// The flag returned by this function matches getDetailTriEdgeFlags in Detour.
// Figure out if edge (va,vb) is part of the polygon boundary.
float thrSqr = 0.001f * 0.001f;
for (int i = 0, j = npoly - 1; i < npoly; j = i++)
{
if (DistancePtSeg2d(verts, va, vpoly, j * 3, i * 3) < thrSqr
&& DistancePtSeg2d(verts, vb, vpoly, j * 3, i * 3) < thrSqr)
{
return 1;
}
}
return 0;
}
static int GetTriFlags(float[] verts, int va, int vb, int vc, float[] vpoly, int npoly)
{
int flags = 0;
flags |= GetEdgeFlags(verts, va, vb, vpoly, npoly) << 0;
flags |= GetEdgeFlags(verts, vb, vc, vpoly, npoly) << 2;
flags |= GetEdgeFlags(verts, vc, va, vpoly, npoly) << 4;
return flags;
}
/// @par
///
/// See the #rcConfig documentation for more information on the configuration parameters.
@ -1599,8 +1609,7 @@ namespace DotRecast.Recast
dmesh.tris[dmesh.ntris * 4 + 0] = tris[t + 0];
dmesh.tris[dmesh.ntris * 4 + 1] = tris[t + 1];
dmesh.tris[dmesh.ntris * 4 + 2] = tris[t + 2];
dmesh.tris[dmesh.ntris * 4 + 3] = GetTriFlags(verts, tris[t + 0] * 3, tris[t + 1] * 3,
tris[t + 2] * 3, poly, npoly);
dmesh.tris[dmesh.ntris * 4 + 3] = tris[t + 3];
dmesh.ntris++;
}
}