Function findAngleDegOfPick

source/MRViewer/MRObjectTransformWidget.cpp:29–85

using namespace MR;

float findAngleDegOfPick( const Vector3f& center, const Vector3f& zeroPoint, const Vector3f& norm,
                          const Line3f& ray, Viewport& vp, const Vector3f& vpPoint )
{
    Plane3f plane1 = Plane3f::fromDirAndPt( norm, center ).normalized();
    Plane3f plane2 = Plane3f::fromDirAndPt( cross( ray.d, center - ray.p ), center ).normalized();
    auto centerVp = vp.projectToViewportSpace( center );
    auto centerRay = vp.unprojectPixelRay( to2dim( centerVp ) );
    bool parallel = std::abs( dot( centerRay.d.normalized(), norm.normalized() ) ) < 0.25f;
    auto planeIntersectionLine = intersection( plane1, plane2 );
    auto radiusVec = ( zeroPoint - center );
    if ( parallel || !planeIntersectionLine )
    {
        auto pickProjS = plane1.project( ray.p );
        auto pickProjF = plane1.project( ray.p + ray.d );

        auto centerProjOnPickLine = Line3f( pickProjS, pickProjF - pickProjS ).project( center );

        auto radiusSq = radiusVec.lengthSq();
        auto line = center - centerProjOnPickLine;
        auto lineSq = line.lengthSq();
        if ( lineSq >= radiusSq )
            planeIntersectionLine = Line3f( centerProjOnPickLine, line );
        else
        {
            auto pInter = centerProjOnPickLine + ( pickProjS - pickProjF ).normalized() *
                std::sqrt( radiusSq - lineSq );
            planeIntersectionLine = Line3f( pInter, center - pInter );
        }
        parallel = true;
    }
    auto vec2 = radiusVec.normalized();
    auto angleSign = mixed( norm.normalized(), planeIntersectionLine->d, vec2 ) < 0.0f ? 1.0f : -1.0f;
    auto angleRes = angleSign * angle( planeIntersectionLine->d.normalized(), vec2 );
    auto sinA = std::sin( angleRes );
    auto cosA = std::cos( angleRes );
    auto crossVec = cross( norm.normalized(), vec2 ).normalized();
    auto p1 = center + cosA * vec2 + sinA * crossVec;
    auto p2 = center - cosA * vec2 - sinA * crossVec;

    auto p1Vp = vp.projectToViewportSpace( p1 );
    auto p2Vp = vp.projectToViewportSpace( p2 );
    auto dist1 = p1Vp - vpPoint;
    auto dist2 = p2Vp - vpPoint;
    float diff = 0.0f;
    if ( !parallel )
        diff = to2dim( dist1 ).lengthSq() - to2dim( dist2 ).lengthSq();
    else
        diff = dist1.z - dist2.z;

    if ( diff > 0.0f || parallel )
    {
        if ( angleRes < 0.0f )
            return angleRes + PI_F;
        return angleRes - PI_F;
    }
    return angleRes;
}
}