Rename step size to gradient delta

DeviceCopyableObjects.h

@@ -357,7 +357,7 @@ struct SpatialField
   enum Type { StructuredRegular, Unstructured, BlockStructured, Unknown, };
   Type type{Unknown};
   unsigned fieldID{UINT_MAX};
-  float baseDT{0.5f};
+  float delta{0.5f};
   GridAccel gridAccel;
   mat4x3 voxelSpaceTransform;
 
@@ -455,12 +455,12 @@ inline bool sampleField(const SpatialField &sf, vec3 P, float &value) {
 VSNRAY_FUNC
 inline bool sampleGradient(const SpatialField &sf, vec3 P, float3 &value) {
   float x0=0, x1=0, y0=0, y1=0, z0=0, z1=0;
-  bool b0 = sampleField(sf, P+float3{sf.baseDT, 0.f, 0.f}, x1);
-  bool b1 = sampleField(sf, P-float3{sf.baseDT, 0.f, 0.f}, x0);
-  bool b2 = sampleField(sf, P+float3{0.f, sf.baseDT, 0.f}, y1);
-  bool b3 = sampleField(sf, P-float3{0.f, sf.baseDT, 0.f}, y0);
-  bool b4 = sampleField(sf, P+float3{0.f, 0.f, sf.baseDT}, z1);
-  bool b5 = sampleField(sf, P-float3{0.f, 0.f, sf.baseDT}, z0);
+  bool b0 = sampleField(sf, P+float3{sf.delta, 0.f, 0.f}, x1);
+  bool b1 = sampleField(sf, P-float3{sf.delta, 0.f, 0.f}, x0);
+  bool b2 = sampleField(sf, P+float3{0.f, sf.delta, 0.f}, y1);
+  bool b3 = sampleField(sf, P-float3{0.f, sf.delta, 0.f}, y0);
+  bool b4 = sampleField(sf, P+float3{0.f, 0.f, sf.delta}, z1);
+  bool b5 = sampleField(sf, P-float3{0.f, 0.f, sf.delta}, z0);
   if (b0 && b1 && b2 && b3 && b4 && b5) {
     value = float3{x1,y1,z1}-float3{x0,y0,z0};
     return true; // TODO

scene/volume/spatial_field/BlockStructuredField.cpp

@@ -116,7 +116,7 @@ void BlockStructuredField::commit()
   vec3 T = voxelBounds.min-m_bounds.min;
   vfield.voxelSpaceTransform = mat4x3(S,T);
 
-  setStepSize(1.f); // used for (gradient) shading ISO's
+  setGradientDelta(1.f);
 
   buildGrid();
 

scene/volume/spatial_field/SpatialField.cpp

@@ -57,14 +57,9 @@ void SpatialField::buildGrid()
       "buildGrid() not implemented for field type");
 }
 
-float SpatialField::stepSize() const
+void SpatialField::setGradientDelta(float delta)
 {
-  return vfield.baseDT;
-}
-
-void SpatialField::setStepSize(float size)
-{
-  vfield.baseDT = size;
+  vfield.delta = delta;
 }
 
 void SpatialField::dispatch()

scene/volume/spatial_field/SpatialField.h

@@ -24,14 +24,12 @@ struct SpatialField : public Object
 
   virtual void buildGrid();
 
-  float stepSize() const;
-
  protected:
   dco::SpatialField vfield;
 
   GridAccel m_gridAccel;
 
-  void setStepSize(float size);
+  void setGradientDelta(float delta);
   void dispatch();
 };
 

scene/volume/spatial_field/StructuredRegularField.cpp

@@ -35,7 +35,7 @@ void StructuredRegularField::commit()
   vec3 T = -bounds().min;
   vfield.voxelSpaceTransform = mat4x3(S,T);
 
-  setStepSize(min_element(m_spacing / 2.f));
+  setGradientDelta(min_element(m_spacing / 2.f));
 
 #if defined(WITH_CUDA) || defined(WITH_HIP)
   texture<float, 3> tex(m_dims.x, m_dims.y, m_dims.z);

scene/volume/spatial_field/UnstructuredField.cpp

@@ -211,7 +211,7 @@ void UnstructuredField::commit()
 #endif
 
   vfield.voxelSpaceTransform = mat4x3(mat3::identity(),vec3f(0.f));
-  setStepSize(minCellDiagonal);
+  setGradientDelta(minCellDiagonal);
 
   buildGrid();
 
@@ -248,7 +248,7 @@ __global__ void UnstructuredField_buildGridGPU(dco::GridAccel    vaccel,
                                                const vec4f      *vertices,
                                                const dco::UElem *elements,
                                                size_t            numElems,
-                                               float             baseDT)
+                                               float             delta)
 {
   size_t cellID = blockIdx.x * size_t(blockDim.x) + threadIdx.x;
 
@@ -282,7 +282,7 @@ __global__ void UnstructuredField_buildGridGPU(dco::GridAccel    vaccel,
         // a macrocell neighborhood:
         //updateMCStepSize(
         //    mcID,vaccel.dims,length(cellBounds.max-cellBounds.min),vaccel.stepSizes);
-        updateMCStepSize(mcID,vaccel.dims,baseDT,vaccel.stepSizes);
+        updateMCStepSize(mcID,vaccel.dims,delta,vaccel.stepSizes);
       }
     }
   }
@@ -301,7 +301,7 @@ void UnstructuredField::buildGrid()
   size_t numThreads = 1024;
   size_t numElems = m_elements.size();
   UnstructuredField_buildGridGPU<<<div_up(numElems, numThreads), numThreads>>>(
-    vaccel, m_vertices.devicePtr(), m_elements.devicePtr(), numElems, vfield.baseDT);
+    vaccel, m_vertices.devicePtr(), m_elements.devicePtr(), numElems, vfield.delta);
 #else
   int3 dims{64, 64, 64};
   box3f worldBounds = {bounds().min,bounds().max};
@@ -351,7 +351,7 @@ void UnstructuredField::buildGrid()
           //updateMCStepSize(
           //    mcID,vaccel.dims,length(cellBounds.max-cellBounds.min),vaccel.stepSizes);
           updateMCStepSize(
-              mcID,vaccel.dims,vfield.baseDT,vaccel.stepSizes);
+              mcID,vaccel.dims,vfield.delta,vaccel.stepSizes);
         }
       }
     }