214 lines
7.4 KiB
C++
214 lines
7.4 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 National Technology & Engineering Solutions of Sandia, LLC (NTESS).
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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-NA0003525 with NTESS,
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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 functions
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#include <vtkm/Math.h>
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#include <vtkm/TypeTraits.h>
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#include <vtkm/Types.h>
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#include <vtkm/VecTraits.h>
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namespace vtkm
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{
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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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inline VTKM_EXEC_CONT 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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using ScalarType = typename detail::FloatingPointReturnType<ValueType>::Type;
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return static_cast<ValueType>((WeightType(1) - weight) * static_cast<ScalarType>(value0) +
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weight * static_cast<ScalarType>(value1));
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}
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template <typename ValueType, vtkm::IdComponent N, typename WeightType>
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VTKM_EXEC_CONT 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 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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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 typename detail::FloatingPointReturnType<T>::Type MagnitudeSquared(const T& x)
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{
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using U = typename detail::FloatingPointReturnType<T>::Type;
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return static_cast<U>(vtkm::Dot(x, x));
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}
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// ----------------------------------------------------------------------------
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namespace detail
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{
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template <typename T>
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VTKM_EXEC_CONT typename detail::FloatingPointReturnType<T>::Type MagnitudeTemplate(
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T x,
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vtkm::TypeTraitsScalarTag)
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{
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return static_cast<typename detail::FloatingPointReturnType<T>::Type>(vtkm::Abs(x));
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}
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template <typename T>
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VTKM_EXEC_CONT typename detail::FloatingPointReturnType<T>::Type MagnitudeTemplate(
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const T& x,
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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 typename detail::FloatingPointReturnType<T>::Type Magnitude(const T& x)
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{
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return detail::MagnitudeTemplate(x, typename vtkm::TypeTraits<T>::DimensionalityTag());
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}
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// ----------------------------------------------------------------------------
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namespace detail
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{
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template <typename T>
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VTKM_EXEC_CONT typename detail::FloatingPointReturnType<T>::Type RMagnitudeTemplate(
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T x,
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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 typename detail::FloatingPointReturnType<T>::Type RMagnitudeTemplate(
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const T& x,
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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 typename detail::FloatingPointReturnType<T>::Type RMagnitude(const T& x)
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{
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return detail::RMagnitudeTemplate(x, typename vtkm::TypeTraits<T>::DimensionalityTag());
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}
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// ----------------------------------------------------------------------------
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namespace detail
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{
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template <typename T>
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VTKM_EXEC_CONT 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 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 T Normal(const T& x)
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{
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return detail::NormalTemplate(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 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 vtkm::Vec<typename detail::FloatingPointReturnType<T>::Type, 3> Cross(
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const vtkm::Vec<T, 3>& x,
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const vtkm::Vec<T, 3>& y)
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{
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return vtkm::Vec<typename detail::FloatingPointReturnType<T>::Type, 3>(
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x[1] * y[2] - x[2] * y[1], x[2] * y[0] - x[0] * y[2], 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 vtkm::Vec<typename detail::FloatingPointReturnType<T>::Type, 3>
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TriangleNormal(const vtkm::Vec<T, 3>& a, const vtkm::Vec<T, 3>& b, 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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