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Merge topic 'avoid-fpe'

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1b541bdd3 Avoid floating point exceptions in rendering code

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Manish Mathai <mmathai@uoregon.edu>
Merge-request: !3154
This commit is contained in:
Kenneth Moreland 2023-11-21 13:59:32 +00:00 committed by Kitware Robot
commit 7523f841b0
3 changed files with 18 additions and 2 deletions
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10
docs/changelog/avoid-rendering-fpe.md Normal file
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@ -0,0 +1,10 @@
# Avoid floating point exceptions in rendering code
There were some places in the rendering code where floating point
exceptions (FPE) could happen under certain circumstances. Often we do not
care about invalid floating point operation in rendering as they often
occur in degenerate cases that don't contribute anyway. However,
simulations that might include VTK-m might turn on FPE to check their own
operations. In such cases, we don't want errant rendering arithmetic
causing an exception and bringing down the whole code. Thus, we turn on FPE
in some of our test platforms and avoid such operations in general.

4
vtkm/rendering/Wireframer.h
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@ -234,7 +234,9 @@ public:
vtkm::Float32 dx = x2 - x1;
vtkm::Float32 dy = y2 - y1;
vtkm::Float32 gradient = (dx == 0.0) ? 1.0f : (dy / dx);
if (dx == 0.0)
dx = vtkm::Epsilon32(); // Avoid FPE
vtkm::Float32 gradient = dy / dx;
vtkm::Float32 xEnd = vtkm::Round(x1);
vtkm::Float32 yEnd = y1 + gradient * (xEnd - x1);

6
vtkm/rendering/raytracing/GlyphIntersector.cxx
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@ -418,7 +418,11 @@ public:
normal[0] = (vtkm::Abs(vtkm::Abs(lp[0]) - 1.0f) <= eps) ? lp[0] : 0.0f;
normal[1] = (vtkm::Abs(vtkm::Abs(lp[1]) - 1.0f) <= eps) ? lp[1] : 0.0f;
normal[2] = (vtkm::Abs(vtkm::Abs(lp[2]) - 1.0f) <= eps) ? lp[2] : 0.0f;
vtkm::Normalize(normal);
Precision magSquared = vtkm::MagnitudeSquared(normal);
if (magSquared > eps)
{
normal = vtkm::RSqrt(magSquared) * normal;
}
// Flip normal if it is pointing the wrong way
if (vtkm::Dot(normal, rayDir) > 0.0f)