229 lines
7.0 KiB
C++
229 lines
7.0 KiB
C++
//=============================================================================
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//
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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//
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//
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// Copyright 2015 Sandia Corporation.
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// Copyright 2015 UT-Battelle, LLC.
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// Copyright 2015 Los Alamos National Security.
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//
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// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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// the U.S. Government retains certain rights in this software.
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// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
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// Laboratory (LANL), the U.S. Government retains certain rights in
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// this software.
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//
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//=============================================================================
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#ifndef vtk_m_VectorAnalysis_h
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#define vtk_m_VectorAnalysis_h
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// This header file defines math functions that deal with linear albegra funcitons
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#include <vtkm/Math.h>
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#include <vtkm/Types.h>
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#include <vtkm/TypeTraits.h>
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#include <vtkm/VecTraits.h>
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namespace vtkm {
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// ----------------------------------------------------------------------------
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/// \brief Returns the linear interpolation of two values based on weight
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///
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/// \c Lerp interpolates return the linerar interpolation of v0 and v1 based on w. v0
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/// and v1 are scalars or vectors of same length. w can either be a scalar or a
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/// vector of the same length as x and y. If w is outside [0,1] then lerp
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/// extrapolates. If w=0 => v0 is returned if w=1 => v1 is returned.
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///
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template<typename ValueType, typename WeightType>
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VTKM_EXEC_CONT
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ValueType Lerp(const ValueType &value0,
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const ValueType &value1,
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const WeightType &weight)
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{
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return static_cast<ValueType>((WeightType(1)-weight)*value0+weight*value1);
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}
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template<typename ValueType, vtkm::IdComponent N, typename WeightType>
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VTKM_EXEC_CONT
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vtkm::Vec<ValueType,N> Lerp(const vtkm::Vec<ValueType,N> &value0,
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const vtkm::Vec<ValueType,N> &value1,
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const WeightType &weight)
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{
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return (WeightType(1)-weight)*value0+weight*value1;
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}
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template<typename ValueType, vtkm::IdComponent N>
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VTKM_EXEC_CONT
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vtkm::Vec<ValueType,N> Lerp(const vtkm::Vec<ValueType,N> &value0,
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const vtkm::Vec<ValueType,N> &value1,
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const vtkm::Vec<ValueType,N> &weight)
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{
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static const vtkm::Vec<ValueType,N> One(ValueType(1));
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return (One-weight)*value0+weight*value1;
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}
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// ----------------------------------------------------------------------------
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/// \brief Returns the square of the magnitude of a vector.
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///
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/// It is usually much faster to compute the square of the magnitude than the
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/// square, so you should use this function in place of Magnitude or RMagnitude
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/// when possible.
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///
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template<typename T>
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VTKM_EXEC_CONT
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typename vtkm::VecTraits<T>::ComponentType
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MagnitudeSquared(const T &x)
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{
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return vtkm::dot(x,x);
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}
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// ----------------------------------------------------------------------------
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namespace detail {
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template<typename T>
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VTKM_EXEC_CONT
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typename detail::FloatingPointReturnType<T>::Type
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MagnitudeTemplate(T x, vtkm::TypeTraitsScalarTag)
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{
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return vtkm::Abs(x);
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}
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template<typename T>
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VTKM_EXEC_CONT
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typename detail::FloatingPointReturnType<T>::Type
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MagnitudeTemplate(const T &x, vtkm::TypeTraitsVectorTag)
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{
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return vtkm::Sqrt(vtkm::MagnitudeSquared(x));
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}
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} // namespace detail
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/// \brief Returns the magnitude of a vector.
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///
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/// It is usually much faster to compute MagnitudeSquared, so that should be
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/// substituted when possible (unless you are just going to take the square
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/// root, which would be besides the point). On some hardware it is also faster
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/// to find the reciprocal magnitude, so RMagnitude should be used if you
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/// actually plan to divide by the magnitude.
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///
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template<typename T>
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VTKM_EXEC_CONT
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typename detail::FloatingPointReturnType<T>::Type
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Magnitude(const T &x)
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{
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return detail::MagnitudeTemplate(
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x, typename vtkm::TypeTraits<T>::DimensionalityTag());
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}
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// ----------------------------------------------------------------------------
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namespace detail {
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template<typename T>
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VTKM_EXEC_CONT
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typename detail::FloatingPointReturnType<T>::Type
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RMagnitudeTemplate(T x, vtkm::TypeTraitsScalarTag)
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{
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return T(1)/vtkm::Abs(x);
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}
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template<typename T>
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VTKM_EXEC_CONT
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typename detail::FloatingPointReturnType<T>::Type
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RMagnitudeTemplate(const T &x, vtkm::TypeTraitsVectorTag)
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{
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return vtkm::RSqrt(vtkm::MagnitudeSquared(x));
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}
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} // namespace detail
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/// \brief Returns the reciprocal magnitude of a vector.
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///
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/// On some hardware RMagnitude is faster than Magnitude, but neither is
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/// as fast as MagnitudeSquared.
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///
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template<typename T>
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VTKM_EXEC_CONT
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typename detail::FloatingPointReturnType<T>::Type
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RMagnitude(const T &x)
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{
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return detail::RMagnitudeTemplate(
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x, typename vtkm::TypeTraits<T>::DimensionalityTag());
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}
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// ----------------------------------------------------------------------------
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namespace detail {
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template<typename T>
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VTKM_EXEC_CONT
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T NormalTemplate(T x, vtkm::TypeTraitsScalarTag)
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{
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return vtkm::CopySign(T(1), x);
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}
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template<typename T>
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VTKM_EXEC_CONT
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T NormalTemplate(const T &x, vtkm::TypeTraitsVectorTag)
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{
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return vtkm::RMagnitude(x)*x;
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}
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} // namespace detail
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/// \brief Returns a normalized version of the given vector.
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///
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/// The resulting vector points in the same direction but has unit length.
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///
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template<typename T>
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VTKM_EXEC_CONT
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T Normal(const T &x)
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{
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return detail::NormalTemplate(
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x, typename vtkm::TypeTraits<T>::DimensionalityTag());
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}
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// ----------------------------------------------------------------------------
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/// \brief Changes a vector to be normal.
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///
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/// The given vector is scaled to be unit length.
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///
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template<typename T>
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VTKM_EXEC_CONT
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void Normalize(T &x)
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{
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x = vtkm::Normal(x);
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}
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// ----------------------------------------------------------------------------
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/// \brief Find the cross product of two vectors.
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///
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template<typename T>
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VTKM_EXEC_CONT
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vtkm::Vec<typename detail::FloatingPointReturnType<T>::Type,3>
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Cross(const vtkm::Vec<T,3> &x, const vtkm::Vec<T,3> &y)
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{
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return vtkm::Vec<typename detail::FloatingPointReturnType<T>::Type,3>(x[1]*y[2] - x[2]*y[1],
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x[2]*y[0] - x[0]*y[2],
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x[0]*y[1] - x[1]*y[0]);
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}
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//-----------------------------------------------------------------------------
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/// \brief Find the normal of a triangle.
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///
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/// Given three coordinates in space, which, unless degenerate, uniquely define
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/// a triangle and the plane the triangle is on, returns a vector perpendicular
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/// to that triangle/plane.
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///
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template<typename T>
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VTKM_EXEC_CONT
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vtkm::Vec<typename detail::FloatingPointReturnType<T>::Type,3>
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TriangleNormal(const vtkm::Vec<T,3> &a,
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const vtkm::Vec<T,3> &b,
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const vtkm::Vec<T,3> &c)
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{
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return vtkm::Cross(b-a, c-a);
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}
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} // namespace vtkm
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#endif //vtk_m_VectorAnalysis_h
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