include/fsdk/Estimators/IHeadPoseEstimator.h

#pragma once

#include <fsdk/IObject.h>
#include <fsdk/FSDKError.h>
#include <fsdk/Optional.h>
#include <fsdk/Types.h>

#include <cmath>

namespace fsdk {

#ifndef DOXYGEN_SHOULD_SKIP_THIS
    DECLARE_SMARTPTR(IHeadPoseEstimator);
#endif

    struct HeadPoseEstimation {
        float pitch; 
        float yaw;   
        float roll;  

        enum FrontalFaceType {
            Non = 0, 
            Good,    
            ISO      
        };

        inline FrontalFaceType getFrontalFaceType() const;
    };

    struct IHeadPoseEstimator : IRefCounted {
        virtual Result<FSDKError>
        estimate(const Image& image, const Detection& detection, HeadPoseEstimation& out) const noexcept = 0;

        virtual Result<FSDKError> estimate(
            Span<const Image> images,
            Span<const Detection> detections,
            Span<HeadPoseEstimation> out) const noexcept = 0;

        virtual Result<FSDKError> validate(
            Span<const Image> images,
            Span<const Detection> detections,
            Span<Result<FSDKError>> errors) const noexcept = 0;
    };

    /*
        Implementation details.
    */
    HeadPoseEstimation::FrontalFaceType HeadPoseEstimation::getFrontalFaceType() const {
        if(std::abs(roll) <= 8 && std::abs(pitch) <= 5 && std::abs(yaw) <= 5)
            return HeadPoseEstimation::ISO;
        if(std::abs(roll) <= 30 && std::abs(pitch) <= 40 && std::abs(yaw) <= 40)
            return HeadPoseEstimation::Good;
        return HeadPoseEstimation::Non;
    }

} // namespace fsdk