From 6d254d3e608bd6798dc0dc4aaab94e1ad7498c67 Mon Sep 17 00:00:00 2001
From: Sujin Philip <sujin.philip@kitware.com>
Date: Fri, 1 Apr 2022 12:40:54 -0400
Subject: [PATCH] Fix StructuredPointGradient for Uniform Point Coordinates

The scalar field difference along x, y, and z should be divided by the
spacing not multiplied. This was causing some test failures in VTK and
ParaView when overriding the default contour filter with `vtkmContour`.
---
 .../worklet/gradient/StructuredPointGradient.h       | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/vtkm/filter/vector_analysis/worklet/gradient/StructuredPointGradient.h b/vtkm/filter/vector_analysis/worklet/gradient/StructuredPointGradient.h
index 8d0c118f6..33e1cb747 100644
--- a/vtkm/filter/vector_analysis/worklet/gradient/StructuredPointGradient.h
+++ b/vtkm/filter/vector_analysis/worklet/gradient/StructuredPointGradient.h
@@ -89,34 +89,34 @@ struct StructuredPointGradient : public vtkm::worklet::WorkletPointNeighborhood
     if (boundary.IsRadiusInXBoundary(1))
     {
       auto dx = inputField.GetUnchecked(1, 0, 0) - inputField.GetUnchecked(-1, 0, 0);
-      outputGradient[0] = static_cast<OT>(dx * (r[0] * 0.5f));
+      outputGradient[0] = static_cast<OT>((dx * 0.5f) / r[0]);
     }
     else
     {
       auto dx = inputField.Get(1, 0, 0) - inputField.Get(-1, 0, 0);
-      outputGradient[0] = static_cast<OT>(dx * r[0]);
+      outputGradient[0] = static_cast<OT>(dx / r[0]);
     }
 
     if (boundary.IsRadiusInYBoundary(1))
     {
       auto dy = inputField.GetUnchecked(0, 1, 0) - inputField.GetUnchecked(0, -1, 0);
-      outputGradient[1] = static_cast<OT>(dy * r[1] * 0.5f);
+      outputGradient[1] = static_cast<OT>((dy * 0.5f) / r[1]);
     }
     else
     {
       auto dy = inputField.Get(0, 1, 0) - inputField.Get(0, -1, 0);
-      outputGradient[1] = static_cast<OT>(dy * (r[1]));
+      outputGradient[1] = static_cast<OT>(dy / (r[1]));
     }
 
     if (boundary.IsRadiusInZBoundary(1))
     {
       auto dz = inputField.GetUnchecked(0, 0, 1) - inputField.GetUnchecked(0, 0, -1);
-      outputGradient[2] = static_cast<OT>(dz * r[2] * 0.5f);
+      outputGradient[2] = static_cast<OT>((dz * 0.5f) / r[2]);
     }
     else
     {
       auto dz = inputField.Get(0, 0, 1) - inputField.Get(0, 0, -1);
-      outputGradient[2] = static_cast<OT>(dz * (r[2]));
+      outputGradient[2] = static_cast<OT>(dz / (r[2]));
     }
 #if (defined(VTKM_CUDA) && defined(VTKM_GCC))
 #pragma GCC diagnostic pop
-- 
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