vtk-m/vtkm/exec/Jacobian.h
2019-04-17 10:57:13 -06:00

240 lines
11 KiB
C++

//============================================================================
// Copyright (c) Kitware, Inc.
// All rights reserved.
// See LICENSE.txt 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.
//============================================================================
#ifndef vtk_m_exec_Jacobian_h
#define vtk_m_exec_Jacobian_h
#include <vtkm/Assert.h>
#include <vtkm/CellShape.h>
#include <vtkm/Math.h>
#include <vtkm/Matrix.h>
#include <vtkm/VectorAnalysis.h>
namespace vtkm
{
namespace exec
{
namespace internal
{
template <typename T>
struct Space2D
{
using Vec3 = vtkm::Vec<T, 3>;
using Vec2 = vtkm::Vec<T, 2>;
Vec3 Origin;
Vec3 Basis0;
Vec3 Basis1;
VTKM_EXEC
Space2D(const Vec3& origin, const Vec3& pointFirst, const Vec3& pointLast)
{
this->Origin = origin;
this->Basis0 = vtkm::Normal(pointFirst - this->Origin);
Vec3 n = vtkm::Cross(this->Basis0, pointLast - this->Origin);
this->Basis1 = vtkm::Normal(vtkm::Cross(this->Basis0, n));
}
VTKM_EXEC
Vec2 ConvertCoordToSpace(const Vec3 coord) const
{
Vec3 vec = coord - this->Origin;
return Vec2(vtkm::Dot(vec, this->Basis0), vtkm::Dot(vec, this->Basis1));
}
template <typename U>
VTKM_EXEC vtkm::Vec<U, 3> ConvertVecFromSpace(const vtkm::Vec<U, 2> vec) const
{
return vec[0] * this->Basis0 + vec[1] * this->Basis1;
}
};
} //namespace internal
#define VTKM_DERIVATIVE_WEIGHTS_HEXAHEDRON(pc, rc, call) \
call(0, (-rc[1] * rc[2]), (-rc[0] * rc[2]), (-rc[0] * rc[1])); \
call(1, (rc[1] * rc[2]), (-pc[0] * rc[2]), (-pc[0] * rc[1])); \
call(2, (pc[1] * rc[2]), (pc[0] * rc[2]), (-pc[0] * pc[1])); \
call(3, (-pc[1] * rc[2]), (rc[0] * rc[2]), (-rc[0] * pc[1])); \
call(4, (-rc[1] * pc[2]), (-rc[0] * pc[2]), (rc[0] * rc[1])); \
call(5, (rc[1] * pc[2]), (-pc[0] * pc[2]), (pc[0] * rc[1])); \
call(6, (pc[1] * pc[2]), (pc[0] * pc[2]), (pc[0] * pc[1])); \
call(7, (-pc[1] * pc[2]), (rc[0] * pc[2]), (rc[0] * pc[1]))
#define VTKM_DERIVATIVE_WEIGHTS_WEDGE(pc, rc, call) \
call(0, (-rc[2]), (-rc[2]), (pc[0] - rc[1])); \
call(1, (0.0f), (rc[2]), (-pc[1])); \
call(2, (rc[2]), (0.0f), (-pc[0])); \
call(3, (-pc[2]), (-pc[2]), (rc[0] - pc[1])); \
call(4, (0.0f), (pc[2]), (pc[1])); \
call(5, (pc[2]), (0.0f), (pc[0]))
#define VTKM_DERIVATIVE_WEIGHTS_PYRAMID(pc, rc, call) \
call(0, (-rc[1] * rc[2]), (-rc[0] * rc[2]), (-rc[0] * rc[1])); \
call(1, (rc[1] * rc[2]), (-pc[0] * rc[2]), (-pc[0] * rc[1])); \
call(2, (pc[1] * rc[2]), (pc[0] * rc[2]), (-pc[0] * pc[1])); \
call(3, (-pc[1] * rc[2]), (rc[0] * rc[2]), (-rc[0] * pc[1])); \
call(4, (0.0f), (0.0f), (1.0f))
#define VTKM_DERIVATIVE_WEIGHTS_QUAD(pc, rc, call) \
call(0, (-rc[1]), (-rc[0])); \
call(1, (rc[1]), (-pc[0])); \
call(2, (pc[1]), (pc[0])); \
call(3, (-pc[1]), (rc[0]))
//-----------------------------------------------------------------------------
// This returns the Jacobian of a hexahedron's (or other 3D cell's) coordinates
// with respect to parametric coordinates. Explicitly, this is (d is partial
// derivative):
//
// | |
// | dx/du dx/dv dx/dw |
// | |
// | dy/du dy/dv dy/dw |
// | |
// | dz/du dz/dv dz/dw |
// | |
//
#define VTKM_ACCUM_JACOBIAN_3D(pointIndex, weight0, weight1, weight2) \
jacobian(0, 0) += static_cast<JacobianType>(wCoords[pointIndex][0] * (weight0)); \
jacobian(1, 0) += static_cast<JacobianType>(wCoords[pointIndex][1] * (weight0)); \
jacobian(2, 0) += static_cast<JacobianType>(wCoords[pointIndex][2] * (weight0)); \
jacobian(0, 1) += static_cast<JacobianType>(wCoords[pointIndex][0] * (weight1)); \
jacobian(1, 1) += static_cast<JacobianType>(wCoords[pointIndex][1] * (weight1)); \
jacobian(2, 1) += static_cast<JacobianType>(wCoords[pointIndex][2] * (weight1)); \
jacobian(0, 2) += static_cast<JacobianType>(wCoords[pointIndex][0] * (weight2)); \
jacobian(1, 2) += static_cast<JacobianType>(wCoords[pointIndex][1] * (weight2)); \
jacobian(2, 2) += static_cast<JacobianType>(wCoords[pointIndex][2] * (weight2))
template <typename WorldCoordType, typename ParametricCoordType, typename JacobianType>
VTKM_EXEC void JacobianFor3DCell(const WorldCoordType& wCoords,
const vtkm::Vec<ParametricCoordType, 3>& pcoords,
vtkm::Matrix<JacobianType, 3, 3>& jacobian,
vtkm::CellShapeTagHexahedron)
{
vtkm::Vec<JacobianType, 3> pc(pcoords);
vtkm::Vec<JacobianType, 3> rc = vtkm::Vec<JacobianType, 3>(JacobianType(1)) - pc;
jacobian = vtkm::Matrix<JacobianType, 3, 3>(JacobianType(0));
VTKM_DERIVATIVE_WEIGHTS_HEXAHEDRON(pc, rc, VTKM_ACCUM_JACOBIAN_3D);
}
template <typename WorldCoordType, typename ParametricCoordType, typename JacobianType>
VTKM_EXEC void JacobianFor3DCell(const WorldCoordType& wCoords,
const vtkm::Vec<ParametricCoordType, 3>& pcoords,
vtkm::Matrix<JacobianType, 3, 3>& jacobian,
vtkm::CellShapeTagWedge)
{
vtkm::Vec<JacobianType, 3> pc(pcoords);
vtkm::Vec<JacobianType, 3> rc = vtkm::Vec<JacobianType, 3>(JacobianType(1)) - pc;
jacobian = vtkm::Matrix<JacobianType, 3, 3>(JacobianType(0));
VTKM_DERIVATIVE_WEIGHTS_WEDGE(pc, rc, VTKM_ACCUM_JACOBIAN_3D);
}
template <typename WorldCoordType, typename ParametricCoordType, typename JacobianType>
VTKM_EXEC void JacobianFor3DCell(const WorldCoordType& wCoords,
const vtkm::Vec<ParametricCoordType, 3>& pcoords,
vtkm::Matrix<JacobianType, 3, 3>& jacobian,
vtkm::CellShapeTagPyramid)
{
vtkm::Vec<JacobianType, 3> pc(pcoords);
vtkm::Vec<JacobianType, 3> rc = vtkm::Vec<JacobianType, 3>(JacobianType(1)) - pc;
jacobian = vtkm::Matrix<JacobianType, 3, 3>(JacobianType(0));
VTKM_DERIVATIVE_WEIGHTS_PYRAMID(pc, rc, VTKM_ACCUM_JACOBIAN_3D);
}
// Derivatives in quadrilaterals are computed in much the same way as
// hexahedra. Review the documentation for hexahedra derivatives for details
// on the math. The major difference is that the equations are performed in
// a 2D space built with make_SpaceForQuadrilateral.
#define VTKM_ACCUM_JACOBIAN_2D(pointIndex, weight0, weight1) \
wcoords2d = space.ConvertCoordToSpace(wCoords[pointIndex]); \
jacobian(0, 0) += wcoords2d[0] * (weight0); \
jacobian(1, 0) += wcoords2d[1] * (weight0); \
jacobian(0, 1) += wcoords2d[0] * (weight1); \
jacobian(1, 1) += wcoords2d[1] * (weight1)
template <typename WorldCoordType,
typename ParametricCoordType,
typename SpaceType,
typename JacobianType>
VTKM_EXEC void JacobianFor2DCell(const WorldCoordType& wCoords,
const vtkm::Vec<ParametricCoordType, 3>& pcoords,
const vtkm::exec::internal::Space2D<SpaceType>& space,
vtkm::Matrix<JacobianType, 2, 2>& jacobian,
vtkm::CellShapeTagQuad)
{
vtkm::Vec<JacobianType, 2> pc(static_cast<JacobianType>(pcoords[0]),
static_cast<JacobianType>(pcoords[1]));
vtkm::Vec<JacobianType, 2> rc = vtkm::Vec<JacobianType, 2>(JacobianType(1)) - pc;
vtkm::Vec<SpaceType, 2> wcoords2d;
jacobian = vtkm::Matrix<JacobianType, 2, 2>(JacobianType(0));
VTKM_DERIVATIVE_WEIGHTS_QUAD(pc, rc, VTKM_ACCUM_JACOBIAN_2D);
}
#if 0
// This code doesn't work, so I'm bailing on it. Instead, I'm just grabbing a
// triangle and finding the derivative of that. If you can do better, please
// implement it.
template<typename WorldCoordType,
typename ParametricCoordType,
typename JacobianType>
VTKM_EXEC
void JacobianFor2DCell(const WorldCoordType &wCoords,
const vtkm::Vec<ParametricCoordType,3> &pcoords,
const vtkm::exec::internal::Space2D<JacobianType> &space,
vtkm::Matrix<JacobianType,2,2> &jacobian,
vtkm::CellShapeTagPolygon)
{
const vtkm::IdComponent numPoints = wCoords.GetNumberOfComponents();
vtkm::Vec<JacobianType,2> pc(pcoords[0], pcoords[1]);
JacobianType deltaAngle = 2*vtkm::Pi<JacobianType>()/numPoints;
jacobian = vtkm::Matrix<JacobianType,2,2>(0);
for (vtkm::IdComponent pointIndex = 0; pointIndex < numPoints; pointIndex++)
{
JacobianType angle = pointIndex*deltaAngle;
vtkm::Vec<JacobianType,2> nodePCoords(0.5f*(vtkm::Cos(angle)+1),
0.5f*(vtkm::Sin(angle)+1));
// This is the vector pointing from the user provided parametric coordinate
// to the node at pointIndex in parametric space.
vtkm::Vec<JacobianType,2> pvec = nodePCoords - pc;
// The weight (the derivative of the interpolation factor) happens to be
// pvec scaled by the cube root of pvec's magnitude.
JacobianType magSqr = vtkm::MagnitudeSquared(pvec);
JacobianType invMag = vtkm::RSqrt(magSqr);
JacobianType scale = invMag*invMag*invMag;
vtkm::Vec<JacobianType,2> weight = scale*pvec;
vtkm::Vec<JacobianType,2> wcoords2d =
space.ConvertCoordToSpace(wCoords[pointIndex]);
jacobian(0,0) += wcoords2d[0] * weight[0];
jacobian(1,0) += wcoords2d[1] * weight[0];
jacobian(0,1) += wcoords2d[0] * weight[1];
jacobian(1,1) += wcoords2d[1] * weight[1];
}
}
#endif
#undef VTKM_ACCUM_JACOBIAN_3D
#undef VTKM_ACCUM_JACOBIAN_2D
}
} // namespace vtkm::exec
#endif //vtk_m_exec_Jacobian_h