Mercurial > gemma
changeset 5703:d2ccf6bb6940 sr-v2
Make plane eval for z-values of triangles numerial more robust.
| author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
|---|---|
| date | Mon, 19 Feb 2024 17:48:13 +0100 |
| parents | fe83406fe7ed |
| children | a68e8eae7273 |
| files | pkg/mesh/raster.go pkg/mesh/vertex.go |
| diffstat | 2 files changed, 22 insertions(+), 3 deletions(-) [+] |
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--- a/pkg/mesh/raster.go Wed Feb 14 22:38:14 2024 +0100 +++ b/pkg/mesh/raster.go Mon Feb 19 17:48:13 2024 +0100 @@ -104,8 +104,10 @@ n++ } - if n > 0 { + if n > 0 && !math.IsNaN(sum) { row[j] = sum / float64(n) + } else { + row[j] = noData } px += r.CellSize } @@ -168,7 +170,7 @@ n++ } - if n > 0 { + if n > 0 && !math.IsNaN(sum) { row[j] -= sum / float64(n) } else { row[j] = noData
--- a/pkg/mesh/vertex.go Wed Feb 14 22:38:14 2024 +0100 +++ b/pkg/mesh/vertex.go Mon Feb 19 17:48:13 2024 +0100 @@ -88,7 +88,24 @@ v0 := t[1].Sub(t[0]) v1 := t[2].Sub(t[0]) - n := v0.Cross(v1).Normalize() + n := v0.Cross(v1) + + // If the length of normal is near zero assume we have + // a plane constant in z with an average z value of + // the three vertices. + // This should protect us from the effects of collinear + // geometries. + l := n.Length() + if l < 1e-7 { + sum := t[0].Z + t[1].Z + t[2].Z + return Plane3D{ + A: 0, + B: 0, + C: 1, + D: -sum / 3, + } + } + n = n.Scale(1 / l) // x*nx+ y*ny+ z*nz + d = 0 // d = - (x*nx+ y*ny + z*nz)