Kernel.h

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#pragma once
#include "Platform.h"
#include "DeclareEnum.h"
 
namespace dyno {
 
    template<typename Real>
    class Kernel
    {
    public:
        DYN_FUNC Kernel() {};
        DYN_FUNC ~Kernel() {};
 
        DYN_FUNC inline virtual Real Weight(const Real r, const Real h)
        {
            return Real(0);
        }
 
        DYN_FUNC inline virtual Real Gradient(const Real r, const Real h)
        {
            return Real(0);
        }
 
        DYN_FUNC inline virtual Real integral(const Real r, const Real h)
        {
            return Real(0);
        }
 
    public:
        Real m_scale = Real(1);
    };
 
    //spiky kernel
    template<typename Real>
    class SpikyKernel : public Kernel<Real>
    {
    public:
        DYN_FUNC SpikyKernel() : Kernel<Real>() {};
        DYN_FUNC ~SpikyKernel() {};
 
        DYN_FUNC inline Real Weight(const Real r, const Real h) override
        {
//          const Real q = r / h;
//          if (q > 1.0f) return 0.0f;
//          else {
//              const Real d = Real(1) - q;
//              const Real hh = h*h;
//              return 15.0f / ((Real)M_PI * hh * h) * d * d * d * this->m_scale;
//          }
            return SpikyKernel<Real>::weight(r, h, this->m_scale);
        }
 
        DYN_FUNC inline Real Gradient(const Real r, const Real h) override
        {
//          const Real q = r / h;
//          if (q > 1.0f) return 0.0;
//          //else if (r==0.0f) return 0.0f;
//          else {
//              const Real d = Real(1) - q;
//              const Real hh = h*h;
//              return -45.0f / ((Real)M_PI * hh*h) *d*d * this->m_scale;
//          }
            return SpikyKernel<Real>::gradient(r, h, this->m_scale);
        }
 
        DYN_FUNC inline Real integral(const Real r, const Real h) override
        {
            return SpikyKernel<Real>::integral(r, h, this->m_scale);
        }
 
        DYN_FUNC static inline Real weight(const Real r, const Real h, Real scale)
        {
            const Real q = r / h;
            if (q > 1.0f) return 0.0f;
            else {
                const Real d = Real(1) - q;
                const Real hh = h * h;
                return 15.0f / ((Real)M_PI * hh * h) * d * d * d * scale;
            }
        }
 
        DYN_FUNC static inline Real gradient(const Real r, const Real h, Real scale)
        {
            const Real q = r / h;
            if (q > 1.0f) return 0.0;
            //else if (r==0.0f) return 0.0f;
            else {
                const Real d = Real(1) - q;
                const Real hh = h * h;
                return -45.0f / ((Real)M_PI * hh*hh) *d*d * scale;
            }
        }
 
        DYN_FUNC static inline Real integral(const Real r, const Real h, Real scale)
        {
            const Real q = r / h;
            if (q > 1.0f) return 0.0f;
            else {
                const Real qq = q * q;
                const Real hh = h * h;
                return -15.0f / ((Real)M_PI * hh) * (q - Real(1.5) * qq + q * qq - Real(0.25) * qq * qq - Real(0.25)) * scale;
            }
        }
    };
 
    template<typename Real>
    class ConstantKernel : public Kernel<Real>
    {
    public:
        DYN_FUNC ConstantKernel() : Kernel<Real>() {};
        DYN_FUNC ~ConstantKernel() {};
 
        DYN_FUNC inline Real Weight(const Real r, const Real h) override
        {
            return Real(1);
        }
 
        DYN_FUNC inline Real Gradient(const Real r, const Real h) override
        {
            return Real(0);
        }
    };
 
 
    template<typename Real>
    class SmoothKernel : public Kernel<Real>
    {
    public:
        DYN_FUNC SmoothKernel() : Kernel<Real>() {};
        DYN_FUNC ~SmoothKernel() {};
 
        DYN_FUNC inline Real Weight(const Real r, const Real h) override
        {
//          const Real q = r / h;
//          if (q > 1.0f) return 0.0f;
//          else {
//              return (1.0f - q*q) * this->m_scale;
//          }
            return SmoothKernel<Real>::weight(r, h, this->m_scale);
        }
 
        DYN_FUNC inline Real Gradient(const Real r, const Real h) override
        {
//          const Real q = r / h;
//          if (q > Real(1)) return Real(0);
//          else {
//              const Real hh = h*h;
//              const Real dd = Real(1) - q*q;
//              const Real alpha = 1.0f;// (Real) 945.0f / (32.0f * (Real)M_PI * hh *h);
//              return -alpha * dd* this->m_scale;
//          }
            return SmoothKernel<Real>::gradient(r, h, this->m_scale);
        }
 
        DYN_FUNC static inline Real weight(const Real r, const Real h, const Real scale)
        {
            const Real q = r / h;
            if (q > 1.0f) return 0.0f;
            else {
                return scale * (1.0f - q * q);
            }
        }
 
        DYN_FUNC static inline Real gradient(const Real r, const Real h, const Real scale)
        {
            const Real q = r / h;
            if (q > Real(1)) return Real(0);
            else {
                const Real hh = h * h;
                const Real dd = Real(1) - q * q;
                const Real alpha = 1.0f;// (Real) 945.0f / (32.0f * (Real)M_PI * hh *h);
                return -alpha * dd* scale;
            }
        }
 
        DYN_FUNC static inline Real integral(const Real r, const Real h, Real scale)
        {
            const Real q = r / h;
            if (q > Real(1)) return Real(0);
            else {
                const Real hh = h * h;
                return 1.0 / (hh * h) * (Real(2) / 3 - q + q * q / Real(3));
            }
        }
    };
 
 
    //spiky kernel
    template<typename Real>
    class CorrectedKernel : public Kernel<Real>
    {
    public:
        DYN_FUNC CorrectedKernel() : Kernel<Real>() {};
        DYN_FUNC ~CorrectedKernel() {};
 
        DYN_FUNC inline Real Weight(const Real r, const Real h) override
        {
            const Real q = r / h;
            SmoothKernel<Real> kernSmooth;
            return q*q*q*kernSmooth.Weight(r, h);
        }
 
        DYN_FUNC inline Real WeightR(const Real r, const Real h)
        {
            const Real q = r / h;
            SmoothKernel<Real> kernSmooth;
            return q*q*kernSmooth.Weight(r, h)/h;
        }
 
        DYN_FUNC inline Real WeightRR(const Real r, const Real h)
        {
            const Real q = r / h;
            SmoothKernel<Real> kernSmooth;
            return q*kernSmooth.Weight(r, h) / (h*h);
        }
    };
 
    //cubic kernel
    template<typename Real>
    class CubicKernel : public Kernel<Real>
    {
    public:
        DYN_FUNC CubicKernel() : Kernel<Real>() {};
        DYN_FUNC ~CubicKernel() {};
 
        DYN_FUNC inline Real Weight(const Real r, const Real h) override
        {
            const Real hh = h*h;
            const Real q = 2.0f*r / h;
 
            const Real alpha = 3.0f / (2.0f * (Real)M_PI * hh * h);
 
            if (q > 2.0f) return 0.0f;
            else if (q >= 1.0f)
            {
                //1/6*(2-q)*(2-q)*(2-q)
                const Real d = 2.0f - q;
                return alpha / 6.0f*d*d*d;
            }
            else
            {
                //(2/3)-q*q+0.5f*q*q*q
                const Real qq = q*q;
                const Real qqq = qq*q;
                return alpha*(2.0f / 3.0f - qq + 0.5f*qqq);
            }
        }
 
        DYN_FUNC inline Real Gradient(const Real r, const Real h) override
        {
            const Real hh = h*h;
            const Real q = 2.0f*r / h;
 
            const Real alpha = 3.0f / (2.0f * (Real)M_PI * hh * h);
 
            if (q > 2.0f) return Real(0);
            else if (q >= 1.0f)
            {
                //-0.5*(2.0-q)*(2.0-q)
                const Real d = 2.0f - q;
                return -0.5f*alpha*d*d;
            }
            else
            {
                //-2q+1.5*q*q
                const Real qq = q*q;
                return alpha*(-2.0f*q + 1.5f*qq);
                //return alpha*(-0.5);
            }
        }
    };
 
    template<typename Real>
    class QuarticKernel : public Kernel<Real>
    {
    public:
        DYN_FUNC QuarticKernel() : Kernel<Real>() {};
        DYN_FUNC ~QuarticKernel() {};
 
        DYN_FUNC inline Real Weight(const Real r, const Real h) override
        {
            const Real hh = h*h;
            const Real q = 2.5f*r / h;
            if (q > 2.5) return 0.0f;
            else if (q > 1.5f)
            {
                const Real d = 2.5f - q;
                const Real dd = d*d;
                return 0.0255f*dd*dd / hh;
            }
            else if (q > 0.5f)
            {
                const Real d = 2.5f - q;
                const Real t = 1.5f - q;
                const Real dd = d*d;
                const Real tt = t*t;
                return 0.0255f*(dd*dd - 5.0f*tt*tt) / hh;
            }
            else
            {
                const Real d = 2.5f - q;
                const Real t = 1.5f - q;
                const Real w = 0.5f - q;
                const Real dd = d*d;
                const Real tt = t*t;
                const Real ww = w*w;
                return 0.0255f*(dd*dd - 5.0f*tt*tt + 10.0f*ww*ww) / hh;
            }
        }
 
        DYN_FUNC inline Real Gradient(const Real r, const Real h) override
        {
            const Real hh = h*h;
            const Real q = 2.5f*r / h;
            if (q > 2.5) return 0.0f;
            else if (q > 1.5f)
            {
                //0.102*(2.5-q)^3
                const Real d = 2.5f - q;
                return -0.102f*d*d*d / hh;
            }
            else if (q > 0.5f)
            {
                const Real d = 2.5f - q;
                const Real t = 1.5f - q;
                return -0.102f*(d*d*d - 5.0f*t*t*t) / hh;
            }
            else
            {
                const Real d = 2.5f - q;
                const Real t = 1.5f - q;
                const Real w = 0.5f - q;
                return -0.102f*(d*d*d - 5.0f*t*t*t + 10.0f*w*w*w) / hh;
            }
        }
    };
}