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vtkFlyingEdges3D.cxx
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vtkFlyingEdges3D.cxx
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/*=========================================================================
Program: Visualization Toolkit
Module: vtkFlyingEdges3D.cxx
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
#include "vtkFlyingEdges3D.h"
#include "vtkArrayListTemplate.h" // For processing attribute data
#include "vtkMath.h"
#include "vtkImageData.h"
#include "vtkCellArray.h"
#include "vtkInformation.h"
#include "vtkInformationIntegerVectorKey.h"
#include "vtkInformationVector.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkFloatArray.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkMarchingCubesTriangleCases.h"
#include "vtkSMPTools.h"
#include <cmath>
vtkStandardNewMacro(vtkFlyingEdges3D);
//----------------------------------------------------------------------------
namespace {
// This templated class implements the heart of the algorithm.
// vtkFlyingEdges3D populates the information in this class and
// then invokes Contour() to actually initiate execution.
template <class T>
class vtkFlyingEdges3DAlgorithm
{
public:
// Edge case table values.
enum EdgeClass {
Below = 0, //below isovalue
Above = 1, //above isovalue
LeftAbove = 1, //left vertex is above isovalue
RightAbove = 2, //right vertex is above isovalue
BothAbove = 3 //entire edge is above isovalue
};
// Dealing with boundary situations when processing volumes.
enum CellClass {
Interior = 0,
MinBoundary = 1,
MaxBoundary = 2
};
// Edge-based case table to generate output triangle primitives. It is
// equivalent to the vertex-based Marching Cubes case table but provides
// several computational advantages (parallel separability, more efficient
// computation). This table is built from the MC case table when the class
// is instantiated.
unsigned char EdgeCases[256][16];
// A table to map old edge ids (as defined from vtkMarchingCubesCases) into
// the edge-based case table. This is so that the existing Marching Cubes
// case tables can be reused.
static const unsigned char EdgeMap[12];
// A table that lists voxel point ids as a function of edge ids (edge ids
// for edge-based case table).
static const unsigned char VertMap[12][2];
// A table describing vertex offsets (in index space) from the cube axes
// origin for each of the eight vertices of a voxel.
static const unsigned char VertOffsets[8][3];
// This table is used to accelerate the generation of output triangles and
// points. The EdgeUses array, a function of the voxel case number,
// indicates which voxel edges intersect with the contour (i.e., require
// interpolation). This array is filled in at instantiation during the case
// table generation process.
unsigned char EdgeUses[256][12];
// Flags indicate whether a particular case requires voxel axes to be
// processed. A cheap acceleration structure computed from the case
// tables at the point of instantiation.
unsigned char IncludesAxes[256];
// Algorithm-derived data. XCases tracks the x-row edge cases. The
// EdgeMetaData tracks information needed for parallel partitioning,
// and to enable generation of the output primitives without using
// a point locator.
unsigned char *XCases;
vtkIdType *EdgeMetaData;
// Internal variables used by the various algorithm methods. Interfaces VTK
// image data in a form more convenient to the algorithm.
T *Scalars;
vtkIdType Dims[3];
double Origin[3];
double Spacing[3];
vtkIdType NumberOfEdges;
vtkIdType SliceOffset;
int Min0;
int Max0;
int Inc0;
int Min1;
int Max1;
int Inc1;
int Min2;
int Max2;
int Inc2;
// Output data. Threads write to partitioned memory.
T *NewScalars;
vtkIdType *NewTris;
float *NewPoints;
float *NewGradients;
float *NewNormals;
bool NeedGradients;
bool InterpolateAttributes;
ArrayList Arrays;
// Setup algorithm
vtkFlyingEdges3DAlgorithm();
// Adjust the origin to the lower-left corner of the volume (if necessary)
void AdjustOrigin()
{
this->Origin[0] = this->Origin[0] + this->Spacing[0]*this->Min0;
this->Origin[1] = this->Origin[1] + this->Spacing[1]*this->Min1;
this->Origin[2] = this->Origin[2] + this->Spacing[2]*this->Min2;;
}
// The three main passes of the algorithm.
void ProcessXEdge(double value, T const * const inPtr, vtkIdType row, vtkIdType slice); //PASS 1
void ProcessYZEdges(vtkIdType row, vtkIdType slice); //PASS 2
void GenerateOutput(double value, T* inPtr, vtkIdType row, vtkIdType slice);//PASS 3
// Place holder for now in case fancy bit fiddling is needed later.
void SetXEdge(unsigned char *ePtr, unsigned char edgeCase)
{*ePtr = edgeCase;}
// Given the four x-edge cases defining this voxel, return the voxel case
// number.
unsigned char GetEdgeCase(unsigned char *ePtr[4])
{
return (*(ePtr[0]) | ((*(ePtr[1]))<<2) | ((*(ePtr[2]))<<4) | ((*(ePtr[3]))<<6));
}
// Return the number of contouring primitives for a particular edge case number.
unsigned char GetNumberOfPrimitives(unsigned char eCase)
{ return this->EdgeCases[eCase][0]; }
// Return an array indicating which voxel edges intersect the contour.
unsigned char *GetEdgeUses(unsigned char eCase)
{ return this->EdgeUses[eCase]; }
// Indicate whether voxel axes need processing for this case.
unsigned char CaseIncludesAxes(unsigned char eCase)
{ return this->IncludesAxes[eCase]; }
// Count edge intersections near volume boundaries.
void CountBoundaryYZInts(unsigned char loc, unsigned char *edgeCases,
vtkIdType *eMD[4]);
// Produce the output triangles for this voxel cell.
void GenerateTris(unsigned char eCase, unsigned char numTris, vtkIdType *eIds,
vtkIdType &triId)
{
vtkIdType *tri;
const unsigned char *edges = this->EdgeCases[eCase] + 1;
for (int i=0; i < numTris; ++i, edges+=3)
{
tri = this->NewTris + 4*triId++;
tri[0] = 3;
tri[1] = eIds[edges[0]];
tri[2] = eIds[edges[1]];
tri[3] = eIds[edges[2]];
}
}
// Compute gradient on interior point.
void ComputeGradient(unsigned char loc, vtkIdType ijk[3],
T const * const s0_start, T const * const s0_end,
T const * const s1_start, T const * const s1_end,
T const * const s2_start, T const * const s2_end,
float g[3])
{
if ( loc == Interior )
{
g[0] = 0.5*( (*s0_start - *s0_end) / this->Spacing[0] );
g[1] = 0.5*( (*s1_start - *s1_end) / this->Spacing[1] );
g[2] = 0.5*( (*s2_start - *s2_end) / this->Spacing[2] );
}
else
{
this->ComputeBoundaryGradient(ijk,
s0_start, s0_end,
s1_start, s1_end,
s2_start, s2_end,
g);
}
}
// Interpolate along a voxel axes edge.
void InterpolateAxesEdge(double t, unsigned char loc,
float x0[3],
T const * const s,
const int incs[3],
float x1[3],
vtkIdType vId,
vtkIdType ijk0[3],
vtkIdType ijk1[3],
float g0[3])
{
float *x = this->NewPoints + 3*vId;
x[0] = x0[0] + t*(x1[0]-x0[0]);
x[1] = x0[1] + t*(x1[1]-x0[1]);
x[2] = x0[2] + t*(x1[2]-x0[2]);
if ( this->NeedGradients )
{
float g1[3];
this->ComputeGradient(loc, ijk1,
s + incs[0], s - incs[0],
s + incs[1], s - incs[1],
s + incs[2], s - incs[2],
g1);
float gTmp0 = g0[0] + t*(g1[0]-g0[0]);
float gTmp1 = g0[1] + t*(g1[1]-g0[1]);
float gTmp2 = g0[2] + t*(g1[2]-g0[2]);
if ( this->NewGradients )
{
float *g = this->NewGradients + 3*vId;
g[0] = gTmp0;
g[1] = gTmp1;
g[2] = gTmp2;
}
if ( this->NewNormals )
{
float *n = this->NewNormals + 3*vId;
n[0] = -gTmp0;
n[1] = -gTmp1;
n[2] = -gTmp2;
vtkMath::Normalize(n);
}
}//if normals or gradients required
if ( this->InterpolateAttributes )
{
vtkIdType v0=ijk0[0] + ijk0[1]*incs[1] + ijk0[2]*incs[2];
vtkIdType v1=ijk1[0] + ijk1[1]*incs[1] + ijk1[2]*incs[2];;
this->Arrays.InterpolateEdge(v0,v1,t,vId);
}
}
// Compute the gradient on a point which may be on the boundary of the volume.
void ComputeBoundaryGradient(vtkIdType ijk[3],
T const * const s0_start, T const * const s0_end,
T const * const s1_start, T const * const s1_end,
T const * const s2_start, T const * const s2_end,
float g[3]);
// Interpolate along an arbitrary edge, typically one that may be on the
// volume boundary. This means careful computation of stuff requiring
// neighborhood information (e.g., gradients).
void InterpolateEdge(double value, vtkIdType ijk[3],
T const * const s, const int incs[3],
float x[3],
unsigned char edgeNum,
unsigned char const* const edgeUses,
vtkIdType *eIds);
// Produce the output points on the voxel axes for this voxel cell.
void GeneratePoints(double value, unsigned char loc, vtkIdType ijk[3],
T const * const sPtr, const int incs[3],
float x[3], unsigned char const * const edgeUses,
vtkIdType *eIds);
// Helper function to set up the point ids on voxel edges.
unsigned char InitVoxelIds(unsigned char *ePtr[4], vtkIdType *eMD[4],
vtkIdType *eIds)
{
unsigned char eCase = GetEdgeCase(ePtr);
eIds[0] = eMD[0][0]; //x-edges
eIds[1] = eMD[1][0];
eIds[2] = eMD[2][0];
eIds[3] = eMD[3][0];
eIds[4] = eMD[0][1]; //y-edges
eIds[5] = eIds[4] + this->EdgeUses[eCase][4];
eIds[6] = eMD[2][1];
eIds[7] = eIds[6] + this->EdgeUses[eCase][6];
eIds[8] = eMD[0][2]; //z-edges
eIds[9] = eIds[8] + this->EdgeUses[eCase][8];
eIds[10] = eMD[1][2];
eIds[11] = eIds[10] + this->EdgeUses[eCase][10];
return eCase;
}
// Helper function to advance the point ids along voxel rows.
void AdvanceVoxelIds(unsigned char eCase, vtkIdType *eIds)
{
eIds[0] += this->EdgeUses[eCase][0]; //x-edges
eIds[1] += this->EdgeUses[eCase][1];
eIds[2] += this->EdgeUses[eCase][2];
eIds[3] += this->EdgeUses[eCase][3];
eIds[4] += this->EdgeUses[eCase][4]; //y-edges
eIds[5] = eIds[4] + this->EdgeUses[eCase][5];
eIds[6] += this->EdgeUses[eCase][6];
eIds[7] = eIds[6] + this->EdgeUses[eCase][7];
eIds[8] += this->EdgeUses[eCase][8]; //z-edges
eIds[9] = eIds[8] + this->EdgeUses[eCase][9];
eIds[10] += this->EdgeUses[eCase][10];
eIds[11] = eIds[10] + this->EdgeUses[eCase][11];
}
// Threading integration via SMPTools
template <class TT> class Pass1
{
public:
vtkFlyingEdges3DAlgorithm<TT> *Algo;
double Value;
Pass1(vtkFlyingEdges3DAlgorithm<TT> *algo, double value)
{this->Algo = algo; this->Value = value;}
void operator()(vtkIdType slice, vtkIdType end)
{
vtkIdType row;
TT *rowPtr, *slicePtr = this->Algo->Scalars + slice*this->Algo->Inc2;
for ( ; slice < end; ++slice )
{
for (row=0, rowPtr=slicePtr; row < this->Algo->Dims[1]; ++row)
{
this->Algo->ProcessXEdge(this->Value, rowPtr, row, slice);
rowPtr += this->Algo->Inc1;
}//for all rows in this slice
slicePtr += this->Algo->Inc2;
}//for all slices in this batch
}
};
template <class TT> class Pass2
{
public:
Pass2(vtkFlyingEdges3DAlgorithm<TT> *algo)
{this->Algo = algo;}
vtkFlyingEdges3DAlgorithm<TT> *Algo;
void operator()(vtkIdType slice, vtkIdType end)
{
for ( ; slice < end; ++slice)
{
for ( vtkIdType row=0; row < (this->Algo->Dims[1]-1); ++row)
{
this->Algo->ProcessYZEdges(row, slice);
}//for all rows in this slice
}//for all slices in this batch
}
};
template <class TT> class Pass4
{
public:
Pass4(vtkFlyingEdges3DAlgorithm<TT> *algo, double value)
{this->Algo = algo; this->Value = value;}
vtkFlyingEdges3DAlgorithm<TT> *Algo;
double Value;
void operator()(vtkIdType slice, vtkIdType end)
{
vtkIdType row;
vtkIdType *eMD0 = this->Algo->EdgeMetaData + slice*6*this->Algo->Dims[1];
vtkIdType *eMD1 = eMD0 + 6*this->Algo->Dims[1];
TT *rowPtr, *slicePtr = this->Algo->Scalars + slice*this->Algo->Inc2;
for ( ; slice < end; ++slice )
{
// It's possible to skip entire slices if there is nothing to generate
if ( eMD1[3] > eMD0[3] ) //there are triangle primitives!
{
for (row=0, rowPtr=slicePtr; row < this->Algo->Dims[1]-1; ++row)
{
this->Algo->GenerateOutput(this->Value, rowPtr, row, slice);
rowPtr += this->Algo->Inc1;
}//for all rows in this slice
}//if there are triangles
slicePtr += this->Algo->Inc2;
eMD0 = eMD1;
eMD1 = eMD0 + 6*this->Algo->Dims[1];
}//for all slices in this batch
}
};
// Interface between VTK and templated functions
static void Contour(vtkFlyingEdges3D *self, vtkImageData *input,
vtkDataArray *inScalars,
int extent[6], vtkIdType *incs, T *scalars,
vtkPolyData *output, vtkPoints *newPts, vtkCellArray *newTris,
vtkDataArray *newScalars,vtkFloatArray *newNormals,
vtkFloatArray *newGradients);
};
//----------------------------------------------------------------------------
// Map MC edges numbering to use the saner FlyingEdges edge numbering scheme.
template <class T> const unsigned char vtkFlyingEdges3DAlgorithm<T>::
EdgeMap[12] = {0,5,1,4,2,7,3,6,8,9,10,11};
//----------------------------------------------------------------------------
// Map MC edges numbering to use the saner FlyingEdges edge numbering scheme.
template <class T> const unsigned char vtkFlyingEdges3DAlgorithm<T>::
VertMap[12][2] = {{0,1}, {2,3}, {4,5}, {6,7}, {0,2}, {1,3}, {4,6}, {5,7},
{0,4}, {1,5}, {2,6}, {3,7}};
//----------------------------------------------------------------------------
// The offsets of each vertex (in index space) from the voxel axes origin.
template <class T> const unsigned char vtkFlyingEdges3DAlgorithm<T>::
VertOffsets[8][3] = {{0,0,0}, {1,0,0}, {0,1,0}, {1,1,0},
{0,0,1}, {1,0,1}, {0,1,1}, {1,1,1}};
//----------------------------------------------------------------------------
// Instantiate and initialize key data members. Mostly we build the
// edge-based case table, and associated acceleration structures, from the
// marching cubes case table. Some of this code is borrowed shamelessly from
// vtkVoxel::Contour() method.
template <class T> vtkFlyingEdges3DAlgorithm<T>::
vtkFlyingEdges3DAlgorithm():XCases(NULL),EdgeMetaData(NULL),NewScalars(NULL),
NewTris(NULL),NewPoints(NULL),NewGradients(NULL),
NewNormals(NULL)
{
int i, j, k, l, ii, eCase, index, numTris;
static int vertMap[8] = {0,1,3,2,4,5,7,6};
static int CASE_MASK[8] = {1,2,4,8,16,32,64,128};
EDGE_LIST *edge;
vtkMarchingCubesTriangleCases *triCase;
unsigned char *edgeCase;
// Initialize cases, increments, and edge intersection flags
for (eCase=0; eCase<256; ++eCase)
{
for (j=0; j<16; ++j)
{
this->EdgeCases[eCase][j] = 0;
}
for (j=0; j<12; ++j)
{
this->EdgeUses[eCase][j] = 0;
}
this->IncludesAxes[eCase] = 0;
}
// The voxel, edge-based case table is a function of the four x-edge cases
// that define the voxel. Here we convert the existing MC vertex-based case
// table into a x-edge case table. Note that the four x-edges are ordered
// (0->3): x, x+y, x+z, x+y+z; the four y-edges are ordered (4->7): y, y+x,
// y+z, y+x+z; and the four z-edges are ordered (8->11): z, z+x, z+y,
// z+x+y.
for (l=0; l<4; ++l)
{
for (k=0; k<4; ++k)
{
for (j=0; j<4; ++j)
{
for (i=0; i<4; ++i)
{
//yes we could just count to (0->255) but where's the fun in that?
eCase = i | (j<<2) | (k<<4) | (l<<6);
for ( ii=0, index = 0; ii < 8; ++ii)
{
if ( eCase & (1<<vertMap[ii]) ) //map into ancient MC table
{
index |= CASE_MASK[ii];
}
}
//Now build case table
triCase = vtkMarchingCubesTriangleCases::GetCases() + index;
edge = triCase->edges;
for ( numTris=0, edge=triCase->edges; edge[0] > -1; edge += 3 )
{//count the number of triangles
numTris++;
}
if ( numTris > 0 )
{
edgeCase = this->EdgeCases[eCase];
*edgeCase++ = numTris;
for ( edge = triCase->edges; edge[0] > -1; edge += 3, edgeCase+=3 )
{
// Build new case table.
edgeCase[0] = this->EdgeMap[edge[0]];
edgeCase[1] = this->EdgeMap[edge[1]];
edgeCase[2] = this->EdgeMap[edge[2]];
}
}
}//x-edges
}//x+y-edges
}//x+z-edges
}//x+y+z-edges
// Okay now build the acceleration structure. This is used to generate
// output points and triangles when processing a voxel x-row as well as to
// perform other topological reasoning. This structure is a function of the
// particular case number.
for (eCase=0; eCase < 256; ++eCase)
{
edgeCase = this->EdgeCases[eCase];
numTris = *edgeCase++;
// Mark edges that are used by this case.
for (i=0; i < numTris*3; ++i) //just loop over all edges
{
this->EdgeUses[eCase][edgeCase[i]] = 1;
}
this->IncludesAxes[eCase] = this->EdgeUses[eCase][0] |
this->EdgeUses[eCase][4] | this->EdgeUses[eCase][8];
}//for all cases
}
//----------------------------------------------------------------------------
// Count intersections along voxel axes. When traversing the volume across
// x-edges, the voxel axes on the boundary may be undefined near boundaries
// (because there are no fully-formed cells). Thus the voxel axes on the
// boundary are treated specially.
template <class T> void vtkFlyingEdges3DAlgorithm<T>::
CountBoundaryYZInts(unsigned char loc, unsigned char *edgeUses,
vtkIdType *eMD[4])
{
switch (loc)
{
case 2: //+x boundary
eMD[0][1] += edgeUses[5];
eMD[0][2] += edgeUses[9];
break;
case 8: //+y
eMD[1][2] += edgeUses[10];
break;
case 10://+x +y
eMD[0][1] += edgeUses[5];
eMD[0][2] += edgeUses[9];
eMD[1][2] += edgeUses[10];
eMD[1][2] += edgeUses[11];
break;
case 32://+z
eMD[2][1] += edgeUses[6];
break;
case 34: //+x +z
eMD[0][1] += edgeUses[5];
eMD[0][2] += edgeUses[9];
eMD[2][1] += edgeUses[6];
eMD[2][1] += edgeUses[7];
break;
case 40: //+y +z
eMD[2][1] += edgeUses[6];
eMD[1][2] += edgeUses[10];
break;
case 42: //+x +y +z happens no more than once per volume
eMD[0][1] += edgeUses[5];
eMD[0][2] += edgeUses[9];
eMD[1][2] += edgeUses[10];
eMD[1][2] += edgeUses[11];
eMD[2][1] += edgeUses[6];
eMD[2][1] += edgeUses[7];
break;
default: //uh-oh shouldn't happen
break;
}
}
//----------------------------------------------------------------------------
// Compute the gradient when the point may be near the boundary of the
// volume.
template <class T> void vtkFlyingEdges3DAlgorithm<T>::
ComputeBoundaryGradient(vtkIdType ijk[3],
T const * const s0_start, T const * const s0_end,
T const * const s1_start, T const * const s1_end,
T const * const s2_start, T const * const s2_end,
float g[3])
{
const T* s = s0_start - this->Inc0;
if ( ijk[0] == 0 )
{
g[0] = (*s0_start - *s) / this->Spacing[0];
}
else if ( ijk[0] >= (this->Dims[0]-1) )
{
g[0] = (*s - *s0_end) / this->Spacing[0];
}
else
{
g[0] = 0.5 * ( (*s0_start - *s0_end) / this->Spacing[0] );
}
if ( ijk[1] == 0 )
{
g[1] = (*s1_start - *s) / this->Spacing[1];
}
else if ( ijk[1] >= (this->Dims[1]-1) )
{
g[1] = (*s - *s1_end) / this->Spacing[1];
}
else
{
g[1] = 0.5 * ( (*s1_start - *s1_end) / this->Spacing[1] );
}
if ( ijk[2] == 0 )
{
g[2] = (*s2_start - *s) / this->Spacing[2];
}
else if ( ijk[2] >= (this->Dims[2]-1) )
{
g[2] = (*s - *s2_end) / this->Spacing[2];
}
else
{
g[2] = 0.5 * ( (*s2_start - *s2_end) / this->Spacing[2] );
}
}
//----------------------------------------------------------------------------
// Interpolate a new point along a boundary edge. Make sure to consider
// proximity to the boundary when computing gradients, etc.
template <class T> void vtkFlyingEdges3DAlgorithm<T>::
InterpolateEdge(double value, vtkIdType ijk[3],
T const * const s,
const int incs[3],
float x[3],
unsigned char edgeNum,
unsigned char const * const edgeUses,
vtkIdType *eIds)
{
// if this edge is not used then get out
if ( ! edgeUses[edgeNum] )
{
return;
}
// build the edge information
const unsigned char *vertMap = this->VertMap[edgeNum];
float x0[3], x1[3];
vtkIdType ijk0[3], ijk1[3], vId=eIds[edgeNum];
int i;
const unsigned char *offsets = this->VertOffsets[vertMap[0]];
T const * const s0 = s + offsets[0]*incs[0] +
offsets[1]*incs[1] +
offsets[2]*incs[2];
for (i=0; i<3; ++i)
{
ijk0[i] = ijk[i] + offsets[i];
x0[i] = x[i] + offsets[i]*this->Spacing[i];
}
offsets = this->VertOffsets[vertMap[1]];
T const * const s1 = s + offsets[0]*incs[0] +
offsets[1]*incs[1] +
offsets[2]*incs[2];
for (i=0; i<3; ++i)
{
ijk1[i] = ijk[i] + offsets[i];
x1[i] = x[i] + offsets[i]*this->Spacing[i];
}
// Okay interpolate
double t = (value - *s0) / (*s1 - *s0);
float *xPtr = this->NewPoints + 3*vId;
xPtr[0] = x0[0] + t*(x1[0]-x0[0]);
xPtr[1] = x0[1] + t*(x1[1]-x0[1]);
xPtr[2] = x0[2] + t*(x1[2]-x0[2]);
if ( this->NeedGradients )
{
float g0[3], g1[3];
this->ComputeBoundaryGradient(ijk0,
s0+incs[0], s0-incs[0],
s0+incs[1], s0-incs[1],
s0+incs[2], s0-incs[2],
g0);
this->ComputeBoundaryGradient(ijk1,
s1+incs[0], s1-incs[0],
s1+incs[1], s1-incs[1],
s1+incs[2], s1-incs[2],
g1);
float gTmp0 = g0[0] + t*(g1[0]-g0[0]);
float gTmp1 = g0[1] + t*(g1[1]-g0[1]);
float gTmp2 = g0[2] + t*(g1[2]-g0[2]);
if (this->NewGradients)
{
float *g = this->NewGradients + 3*vId;
g[0] = gTmp0;
g[1] = gTmp1;
g[2] = gTmp2;
}
if ( this->NewNormals )
{
float *n = this->NewNormals + 3*vId;
n[0] = -gTmp0;
n[1] = -gTmp1;
n[2] = -gTmp2;
vtkMath::Normalize(n);
}
}//if normals or gradients required
if ( this->InterpolateAttributes )
{
vtkIdType v0=ijk0[0] + ijk0[1]*incs[1] + ijk0[2]*incs[2];
vtkIdType v1=ijk1[0] + ijk1[1]*incs[1] + ijk1[2]*incs[2];;
this->Arrays.InterpolateEdge(v0,v1,t,vId);
}
}
//----------------------------------------------------------------------------
// Generate the output points and optionally normals, gradients and
// interpolate attributes.
template <class T> void vtkFlyingEdges3DAlgorithm<T>::
GeneratePoints(double value, unsigned char loc, vtkIdType ijk[3],
T const * const sPtr, const int incs[3],
float x[3],
unsigned char const * const edgeUses,
vtkIdType *eIds)
{
// Create a slightly faster path for voxel axes interior to the volume.
float g0[3];
if ( this->NeedGradients )
{
this->ComputeGradient(loc,ijk,
sPtr + incs[0], sPtr - incs[0],
sPtr + incs[1], sPtr - incs[1],
sPtr + incs[2], sPtr - incs[2],
g0);
}
// Interpolate the cell axes edges
for(int i=0; i < 3; ++i)
{
if(edgeUses[i*4])
{
//edgesUses[0] == x axes edge
//edgesUses[4] == y axes edge
//edgesUses[8] == z axes edge
float x1[3] = {x[0], x[1], x[2] }; x1[i] += this->Spacing[i];
vtkIdType ijk1[3] = { ijk[0], ijk[1], ijk[2] }; ++ijk1[i];
T const * const sPtr2 = (sPtr+incs[i]);
double t = (value - *sPtr) / (*sPtr2 - *sPtr);
this->InterpolateAxesEdge(t, loc, x, sPtr2, incs, x1, eIds[i*4], ijk, ijk1, g0);
}
}
// On the boundary cells special work has to be done to cover the partial
// cell axes. These are boundary situations where the voxel axes is not
// fully formed. These situations occur on the +x,+y,+z volume
// boundaries. (The other cases fall through the default: case which is
// expected.)
//
// Note that loc is one of 27 regions in the volume, with (0,1,2)
// indicating (interior, min, max) along coordinate axes.
switch (loc)
{
case 2: case 6: case 18: case 22: //+x
this->InterpolateEdge(value, ijk, sPtr, incs, x, 5, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 9, edgeUses, eIds);
break;
case 8: case 9: case 24: case 25: //+y
this->InterpolateEdge(value, ijk, sPtr, incs, x, 1, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 10, edgeUses, eIds);
break;
case 32: case 33: case 36: case 37: //+z
this->InterpolateEdge(value, ijk, sPtr, incs, x, 2, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 6, edgeUses, eIds);
break;
case 10: case 26: //+x +y
this->InterpolateEdge(value, ijk, sPtr, incs, x, 1, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 5, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 9, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 10, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 11, edgeUses, eIds);
break;
case 34: case 38: //+x +z
this->InterpolateEdge(value, ijk, sPtr, incs, x, 2, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 5, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 9, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 6, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 7, edgeUses, eIds);
break;
case 40: case 41: //+y +z
this->InterpolateEdge(value, ijk, sPtr, incs, x, 1, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 2, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 3, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 6, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 10, edgeUses, eIds);
break;
case 42: //+x +y +z happens no more than once per volume
this->InterpolateEdge(value, ijk, sPtr, incs, x, 1, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 2, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 3, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 5, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 9, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 10, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 11, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 6, edgeUses, eIds);
this->InterpolateEdge(value, ijk, sPtr, incs, x, 7, edgeUses, eIds);
break;
default: //interior, or -x,-y,-z boundaries
return;
}
}
//----------------------------------------------------------------------------
// PASS 1: Process a single volume x-row (and all of the voxel edges that
// compose the row). Determine the x-edges case classification, count the
// number of x-edge intersections, and figure out where intersections along
// the x-row begins and ends (i.e., gather information for computational
// trimming).
template <class T> void vtkFlyingEdges3DAlgorithm<T>::
ProcessXEdge(double value, T const* const inPtr, vtkIdType row, vtkIdType slice)
{
vtkIdType nxcells=this->Dims[0]-1;
vtkIdType minInt=nxcells, maxInt = 0;
vtkIdType *edgeMetaData;
unsigned char edgeCase, *ePtr=this->XCases+slice*this->SliceOffset+row*nxcells;
double s0, s1 = static_cast<double>(*inPtr);
vtkIdType sum = 0;
//run along the entire x-edge computing edge cases
edgeMetaData = this->EdgeMetaData + (slice*this->Dims[1] + row)*6;
std::fill_n(edgeMetaData, 6, 0);
//pull this out help reduce false sharing
vtkIdType inc0 = this->Inc0;
for (vtkIdType i=0; i < nxcells; ++i, ++ePtr)
{
s0 = s1;
s1 = static_cast<double>(*(inPtr + (i+1)*inc0));
if (s0 >= value)
{
edgeCase = vtkFlyingEdges3DAlgorithm::LeftAbove;
}
else
{
edgeCase = vtkFlyingEdges3DAlgorithm::Below;
}
if( s1 >= value)
{
edgeCase |= vtkFlyingEdges3DAlgorithm::RightAbove;
}
this->SetXEdge(ePtr, edgeCase);
// if edge intersects contour
if ( edgeCase == vtkFlyingEdges3DAlgorithm::LeftAbove ||
edgeCase == vtkFlyingEdges3DAlgorithm::RightAbove )
{
++sum; //increment number of intersections along x-edge
if ( i < minInt )
{
minInt = i;
}
maxInt = i + 1;
}//if contour interacts with this x-edge
}//for all x-cell edges along this x-edge
edgeMetaData[0] += sum; //write back the number of intersections along x-edge
// The beginning and ending of intersections along the edge is used for
// computational trimming.
edgeMetaData[4] = minInt; //where intersections start along x edge
edgeMetaData[5] = maxInt; //where intersections end along x edge
}
//----------------------------------------------------------------------------
// PASS 2: Process a single x-row of voxels. Count the number of y- and
// z-intersections by topological reasoning from x-edge cases. Determine the
// number of primitives (i.e., triangles) generated from this row. Use
// computational trimming to reduce work. Note *ePtr[4] is four pointers to
// four x-edge rows that bound the voxel x-row and which contain edge case
// information.
template <class T> void vtkFlyingEdges3DAlgorithm<T>::
ProcessYZEdges(vtkIdType row, vtkIdType slice)
{
// Grab the four edge cases bounding this voxel x-row.
unsigned char *ePtr[4], ec0, ec1, ec2, ec3, xInts=1;
ePtr[0] = this->XCases + slice*this->SliceOffset + row*(this->Dims[0]-1);
ePtr[1] = ePtr[0] + this->Dims[0]-1;
ePtr[2] = ePtr[0] + this->SliceOffset;
ePtr[3] = ePtr[2] + this->Dims[0]-1;
// Grab the edge meta data surrounding the voxel row.
vtkIdType *eMD[4];
eMD[0] = this->EdgeMetaData + (slice*this->Dims[1] + row)*6; //this x-edge
eMD[1] = eMD[0] + 6; //x-edge in +y direction
eMD[2] = eMD[0] + this->Dims[1]*6; //x-edge in +z direction
eMD[3] = eMD[2] + 6; //x-edge in +y+z direction
// Determine whether this row of x-cells needs processing. If there are no
// x-edge intersections, and the state of the four bounding x-edges is the
// same, then there is no need for processing.
if ( (eMD[0][0] | eMD[1][0] | eMD[2][0] | eMD[3][0]) == 0 ) //any x-ints?
{
if ( *(ePtr[0]) == *(ePtr[1]) && *(ePtr[1]) == *(ePtr[2]) &&
*(ePtr[2]) == *(ePtr[3]) )
{
return; //there are no y- or z-ints, thus no contour, skip voxel row
}
else
{
xInts = 0; //there are y- or z- edge ints however
}
}
// Determine proximity to the boundary of volume. This information is used
// to count edge intersections in boundary situations.
unsigned char loc, yLoc, zLoc, yzLoc;
yLoc = (row >= (this->Dims[1]-2) ? MaxBoundary : Interior);
zLoc = (slice >= (this->Dims[2]-2) ? MaxBoundary : Interior);
yzLoc = (yLoc << 2) | (zLoc << 4);
// The trim edges may need adjustment if the contour travels between rows
// of x-edges (without intersecting these x-edges). This means checking
// whether the trim faces at (xL,xR) made up of the y-z edges intersect the
// contour. Basically just an intersection operation. Determine the voxel
// row trim edges, need to check all four x-edges.
vtkIdType xL=eMD[0][4], xR=eMD[0][5];
vtkIdType i;
if ( xInts )
{
for (i=1; i < 4; ++i)
{
xL = ( eMD[i][4] < xL ? eMD[i][4] : xL);
xR = ( eMD[i][5] > xR ? eMD[i][5] : xR);
}
if ( xL > 0 ) //if trimmed in the -x direction
{
ec0 = *(ePtr[0]+xL); ec1 = *(ePtr[1]+xL);
ec2 = *(ePtr[2]+xL); ec3 = *(ePtr[3]+xL);
if ( (ec0 & 0x1) != (ec1 & 0x1) || (ec1 & 0x1) != (ec2 & 0x1) ||
(ec2 & 0x1) != (ec3 & 0x1) )
{
xL = eMD[0][4] = 0; //reset left trim
}
}
if ( xR < (this->Dims[0]-1) ) //if trimmed in the +x direction
{
ec0 = *(ePtr[0]+xR); ec1 = *(ePtr[1]+xR);
ec2 = *(ePtr[2]+xR); ec3 = *(ePtr[3]+xR);
if ( (ec0 & 0x2) != (ec1 & 0x2) || (ec1 & 0x2) != (ec2 & 0x2) ||
(ec2 & 0x2) != (ec3 & 0x2) )
{
xR = eMD[0][5] = this->Dims[0]-1; //reset right trim
}
}
}
else //contour cuts through without intersecting x-edges, reset trim edges
{
xL = eMD[0][4] = 0;
xR = eMD[0][5] = this->Dims[0]-1;
}
// Okay run along the x-voxels and count the number of y- and
// z-intersections. Here we are just checking y,z edges that make up the
// voxel axes. Also check the number of primitives generated.
unsigned char *edgeUses, eCase, numTris;
ePtr[0] += xL; ePtr[1] += xL; ePtr[2] += xL; ePtr[3] += xL;
const vtkIdType dim0Wall = this->Dims[0]-2;
for (i=xL; i < xR; ++i) //run along the trimmed x-voxels
{
eCase = this->GetEdgeCase(ePtr);
if ( (numTris=this->GetNumberOfPrimitives(eCase)) > 0 )
{
// Okay let's increment the triangle count.
eMD[0][3] += numTris;
// Count the number of y- and z-points to be generated. Pass# 1 counted
// the number of x-intersections along the x-edges. Now we count all
// intersections on the y- and z-voxel axes.
edgeUses = this->GetEdgeUses(eCase);
eMD[0][1] += edgeUses[4]; //y-voxel axes edge always counted
eMD[0][2] += edgeUses[8]; //z-voxel axes edge always counted
loc = yzLoc | (i >= dim0Wall ? MaxBoundary : Interior);
if ( loc != 0 )
{
this->CountBoundaryYZInts(loc,edgeUses,eMD);
}
}//if cell contains contour
// advance the four pointers along voxel row
ePtr[0]++; ePtr[1]++; ePtr[2]++; ePtr[3]++;
}//for all voxels along this x-edge