From 416916310a3c6dba86f8a34123c3070899cd570d Mon Sep 17 00:00:00 2001
From: clyne <clyne@ucar.edu>
Date: Mon, 14 Feb 2022 08:08:02 -0700
Subject: [PATCH] Fixed #3018 - Artifacts in slice renderer kalundquist data
 (#3019)

Floating point round off error in VAPoR::BarycentricCoordsTri()
---
 lib/vdc/vizutil.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/vdc/vizutil.cpp b/lib/vdc/vizutil.cpp
index 07089437c1..2f2deea870 100644
--- a/lib/vdc/vizutil.cpp
+++ b/lib/vdc/vizutil.cpp
@@ -1,5 +1,6 @@
 #include <cmath>
 #include <iostream>
+#include <limits>
 #include "vapor/VAssert.h"
 #include <vapor/vizutil.h>
 
@@ -186,6 +187,11 @@ bool VAPoR::BarycentricCoordsTri(const double verts[], const double pt[], double
     lambda[2] = (d00 * d21 - d01 * d20) / denom;
     lambda[0] = 1.0f - lambda[1] - lambda[2];
 
+    const double epsilon = std::numeric_limits<double>::epsilon();
+    if ((lambda[0] < 0.0) && ((lambda[0] + epsilon) >= 0.0)) lambda[0] = 0.0;
+    if ((lambda[1] < 0.0) && ((lambda[1] + epsilon) >= 0.0)) lambda[1] = 0.0;
+    if ((lambda[2] < 0.0) && ((lambda[2] + epsilon) >= 0.0)) lambda[2] = 0.0;
+
     return (lambda[0] >= 0.0 && lambda[1] >= 0.0 && lambda[2] >= 0.0);
 }