ENH: Compute gradients not normals (since not normalized).

include/ImpBool.hh

@@ -47,7 +47,7 @@ public:
 
   // ImplicitFunction interface
   float Evaluate(float x, float y, float z);
-  void EvaluateNormal(float x, float y, float z, float n[3]);
+  void EvaluateGradient(float x, float y, float z, float g[3]);
 
   // Override modified time retrieval because of object dependencies.
   unsigned long int GetMTime();

include/ImpFunc.hh

@@ -33,8 +33,8 @@ public:
   virtual float Evaluate(float x, float y, float z) = 0;
 
   // Description:
-  // Evaluate function normal at position x-y-z and pass back vector.
-  virtual void EvaluateNormal(float x, float y, float z, float n[3]) = 0;
+  // Evaluate function gradient at position x-y-z and pass back vector.
+  virtual void EvaluateGradient(float x, float y, float z, float g[3]) = 0;
 
 };
 

include/Plane.hh

@@ -39,7 +39,7 @@ public:
   // ImplicitFunction interface
   float Evaluate(float x, float y, float z);
   float Evaluate(float normal[3], float origin[3], float x[3]);
-  void EvaluateNormal(float x, float y, float z, float n[3]);
+  void EvaluateGradient(float x, float y, float z, float g[3]);
 
   vlSetVector3Macro(Normal,float);
   vlGetVectorMacro(Normal,float,3);

include/Sphere.hh

@@ -15,7 +15,7 @@ Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen 1993, 1994
 =========================================================================*/
 // .NAME vlSphere - implicit function for a sphere
 // .SECTION Description
-// vlSphere computes the implicit function and surface normal for a sphere.
+// vlSphere computes the implicit function and/or gradient for a sphere.
 // vlSphere is a concrete implementation of vlImplicitFunction.
 
 #ifndef __vlSphere_h
@@ -32,7 +32,7 @@ public:
 
   // ImplicitFunction interface
   float Evaluate(float x, float y, float z);
-  void EvaluateNormal(float x, float y, float z, float n[3]);
+  void EvaluateGradient(float x, float y, float z, float n[3]);
 
   vlSetMacro(Radius,float);
   vlGetMacro(Radius,float);

src/ImpBool.cc

@@ -108,8 +108,8 @@ float vlImplicitBoolean::Evaluate(float x, float y, float z)
 }
 
 // Description
-// Evaluate sphere normal.
-void vlImplicitBoolean::EvaluateNormal(float x, float y, float z, float n[3])
+// Evaluate gradient of boolean combination.
+void vlImplicitBoolean::EvaluateGradient(float x, float y, float z, float g[3])
 {
   float value, v;
   vlImplicitFunction *f;
@@ -122,7 +122,7 @@ void vlImplicitBoolean::EvaluateNormal(float x, float y, float z, float n[3])
       if ( (v=f->Evaluate(x,y,z)) < value )
         {
         value = v;
-        f->EvaluateNormal(x,y,z,n);
+        f->EvaluateGradient(x,y,z,g);
         }
       }
     }
@@ -135,21 +135,21 @@ void vlImplicitBoolean::EvaluateNormal(float x, float y, float z, float n[3])
       if ( (v=f->Evaluate(x,y,z)) > value ) 
         {
         value = v;
-        f->EvaluateNormal(x,y,z,n);
+        f->EvaluateGradient(x,y,z,g);
         }
       }
     }
 
   else //difference
     {
-    float nTemp[3];
+    float gTemp[3];
     vlImplicitFunction *firstF;
     this->FunctionList.InitTraversal();
     if ( (firstF = this->FunctionList.GetNextItem()) != NULL )
       {
       value = firstF->Evaluate(x,y,z);
-      firstF->EvaluateNormal(x,y,z,nTemp); 
-      n[0] = -1.0*nTemp[0]; n[1] = -1.0*nTemp[1]; n[2] = -1.0*nTemp[2];
+      firstF->EvaluateGradient(x,y,z,gTemp); 
+      g[0] = -1.0*gTemp[0]; g[1] = -1.0*gTemp[1]; g[2] = -1.0*gTemp[2];
       }
 
     for (this->FunctionList.InitTraversal(); 
@@ -160,8 +160,8 @@ void vlImplicitBoolean::EvaluateNormal(float x, float y, float z, float n[3])
         if ( (v=(-1.0)*f->Evaluate(x,y,z)) > value )
           {
           value = v;
-          f->EvaluateNormal(x,y,z,nTemp);
-          n[0] = -1.0*nTemp[0]; n[1] = -1.0*nTemp[1]; n[2] = -1.0*nTemp[2];
+          f->EvaluateGradient(x,y,z,gTemp);
+          g[0] = -1.0*gTemp[0]; g[1] = -1.0*gTemp[1]; g[2] = -1.0*gTemp[2];
           }
         }
       }

src/Plane.cc

@@ -55,8 +55,8 @@ float vlPlane::Evaluate(float x, float y, float z)
 }
 
 // Description
-// Evaluate plane normal at point (x,y,z).
-void vlPlane::EvaluateNormal(float x, float y, float z, float n[3])
+// Evaluate function gradient at point (x,y,z).
+void vlPlane::EvaluateGradient(float x, float y, float z, float n[3])
 {
   for (int i=0; i<3; i++) n[i] = this->Normal[i];
 }

src/Sphere.cc

@@ -37,8 +37,8 @@ float vlSphere::Evaluate(float x, float y, float z)
 }
 
 // Description
-// Evaluate sphere normal.
-void vlSphere::EvaluateNormal(float x, float y, float z, float n[3])
+// Evaluate sphere gradient.
+void vlSphere::EvaluateGradient(float x, float y, float z, float n[3])
 {
   n[0] = 2.0 * (x - this->Center[0]);
   n[1] = 2.0 * (y - this->Center[1]);