/*
 * Copyright information removed for SIGGRAPH anonymous review process.
 * This file is licensed under the GNU General Public License.
 */

#include "m_estimator.h" 

namespace OGF {

    static double weight_One(double r, double w) {
        return 1.0 ;
    }

    static double weight_L1_L2(double r, double w) {
        return 1.0 / sqrt(1.0 + ogf_sqr(r) / 2.0) ;
    }

    static double weight_Lp(double r, double w) {
        const double nu = 1.2 ;
        double abs_r = ogf_max(1e-6, ::fabs(r)) ;
        return ::pow(abs_r, nu - 2.0) ;
    }
    
    static double weight_Fair(double r, double w) {
        return 1.0 / (1.0 + r / w) ;
    }

    static double weight_Huber(double r, double w) {
        double abs_r = ::fabs(r) ;
        return (abs_r < w) ? 1.0 : (w / abs_r) ;
    }

    static double weight_Cauchy(double r, double w) {
        return 1.0 / (1.0 + ogf_sqr(r / w)) ;
    }

    static double weight_Geman_McClure(double r, double w) {
        return 1.0 / ogf_sqr(1.0 + ogf_sqr(r)) ;
    }

    static double weight_Welsch(double r, double w) {
        return ::exp(-ogf_sqr(r/w)) ;
    }

    static double weight_Tuckey(double r, double w) {
        return (::fabs(r) > w) ? 0.0 : ogf_sqr(1.0 - ogf_sqr(r/w)) ;
    }

    MEstimator::MEstimator() :  weight_func_ptr_(&weight_Lp), width_(0.5) { 
    }

    void MEstimator::set_weighting_function(MEstimatorWeight x) {
        switch(x) {
        case M_EST_L2: {
            weight_func_ptr_ = &weight_One ;
        } break ;
        case M_EST_L1_L2: {
            weight_func_ptr_ = &weight_L1_L2 ;
        } break ;
        case M_EST_LP: {
            weight_func_ptr_ = &weight_Lp ;
        } break ;
        case M_EST_FAIR: {
            weight_func_ptr_ = &weight_Fair ;
        } break ;
        case M_EST_HUBER: {
            weight_func_ptr_ = &weight_Huber ;
        } break ;
        case M_EST_CAUCHY: {
            weight_func_ptr_ = &weight_Cauchy ;
        } break ;
        case M_EST_GEMAN_MCCLURE: {
            weight_func_ptr_ = &weight_Geman_McClure ;
        } break ;
        case M_EST_WELSCH: {
            weight_func_ptr_ = &weight_Welsch ;
        } break ;
        case M_EST_TUCKEY: {
            weight_func_ptr_ = &weight_Tuckey ;
        } break ;
        default: {
            assert(false) ;
        } break ;
        }
    }
        
}