make scalar normilization consistent across rendering

vtkm/rendering/Wireframer.h

@@ -185,8 +185,7 @@ public:
     if (fieldLength == 0.f)
     {
       // constant color
-      FieldMin = 0.f;
-      InverseFieldDelta = 1.f;
+      InverseFieldDelta = 0.f;
     }
     else
     {

vtkm/rendering/raytracing/CylinderIntersector.cxx

@@ -383,17 +383,13 @@ public:
     {
       // support the scalar renderer
       Normalize = false;
-      MinScalar = 0;
-      invDeltaScalar = 1;
+      invDeltaScalar = Precision(0.f);
     }
     else
     {
       //Make sure the we don't divide by zero on
       //something like an iso-surface
-      if (maxScalar - MinScalar != 0.f)
-        invDeltaScalar = 1.f / (maxScalar - MinScalar);
-      else
-        invDeltaScalar = 1.f / minScalar;
+      invDeltaScalar = 1.f / (maxScalar - MinScalar);
     }
   }
   typedef void ControlSignature(FieldIn, FieldInOut, WholeArrayIn, WholeArrayIn);

vtkm/rendering/raytracing/QuadIntersector.cxx

@@ -370,17 +370,13 @@ public:
     {
       // support the scalar renderer
       Normalize = false;
-      MinScalar = 0;
-      invDeltaScalar = 1;
+      invDeltaScalar = Precision(0.f);
     }
     else
     {
       //Make sure the we don't divide by zero on
       //something like an iso-surface
-      if (maxScalar - MinScalar != 0.f)
-        invDeltaScalar = 1.f / (maxScalar - MinScalar);
-      else
-        invDeltaScalar = 1.f / minScalar;
+      invDeltaScalar = 1.f / (maxScalar - MinScalar);
     }
   }
   typedef void ControlSignature(FieldIn, FieldOut, WholeArrayIn, WholeArrayIn);

vtkm/rendering/raytracing/SphereIntersector.cxx

@@ -261,17 +261,13 @@ public:
     {
       // support the scalar renderer
       Normalize = false;
-      MinScalar = 0;
-      invDeltaScalar = 1;
+      invDeltaScalar = Precision(0.f);
     }
     else
     {
       //Make sure the we don't divide by zero on
       //something like an iso-surface
-      if (maxScalar - MinScalar != 0.f)
-        invDeltaScalar = 1.f / (maxScalar - MinScalar);
-      else
-        invDeltaScalar = 1.f / minScalar;
+      invDeltaScalar = 1.f / (maxScalar - MinScalar);
     }
   }
   typedef void ControlSignature(FieldIn, FieldOut, WholeArrayIn, WholeArrayIn);

vtkm/rendering/raytracing/TriangleIntersector.cxx

@@ -319,17 +319,13 @@ public:
       {
         // support the scalar renderer
         Normalize = false;
-        MinScalar = 0;
-        invDeltaScalar = 1;
+        invDeltaScalar = Precision(0.f);
       }
       else
       {
         //Make sure the we don't divide by zero on
         //something like an iso-surface
-        if (maxScalar - MinScalar != 0.f)
-          invDeltaScalar = 1.f / (maxScalar - MinScalar);
-        else
-          invDeltaScalar = 1.f / minScalar;
+        invDeltaScalar = 1.f / (maxScalar - MinScalar);
       }
     }