rodriguesRotation.hpp

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#pragma once
 
#include <cmath>
 
#include "NumCpp/NdArray.hpp"
#include "NumCpp/Vector/Vec3.hpp"
 
namespace nc::rotations
{
    //============================================================================
    // Method Description:
    inline Vec3 rodriguesRotation(const Vec3& k, double theta, const Vec3& v) noexcept
    {
        const auto kUnit = k.normalize();
 
        const auto vCosTheta = v * std::cos(theta);
 
        auto kCrossV = kUnit.cross(v);
        kCrossV *= std::sin(theta);
 
        const auto kDotV  = kUnit.dot(v);
        auto       kkDotV = kUnit * kDotV;
        kkDotV *= 1 - std::cos(theta);
 
        auto vec = vCosTheta + kCrossV;
        vec += kkDotV;
 
        return vec;
    }
 
    //============================================================================
    // Method Description:
    template<typename dtype>
    NdArray<double> rodriguesRotation(const NdArray<dtype>& k, double theta, const NdArray<dtype>& v)
    {
        return rodriguesRotation(Vec3(k), theta, Vec3(v)).toNdArray();
    }
} // namespace nc::rotations