/////////////////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2017     Statoil ASA
//
//  ResInsight is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
//  FITNESS FOR A PARTICULAR PURPOSE.
//
//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
//  for more details.
//
/////////////////////////////////////////////////////////////////////////////////

#include "RigTesselatorTools.h"

#include "cvfMath.h"

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
RigEllipsisTesselator::RigEllipsisTesselator( size_t numSlices )
{
    computeCirclePoints( numSlices );
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
void RigEllipsisTesselator::tesselateEllipsis( float a, float b, std::vector<cvf::uint>* triangleIndices, std::vector<cvf::Vec3f>* nodeCoords )
{
    // See http://mathworld.wolfram.com/Ellipse.html

    for ( auto v : m_circlePoints )
    {
        v.x() = v.x() * a;
        v.y() = v.y() * b;

        nodeCoords->push_back( v );
    }

    *triangleIndices = m_circleConnectivities;
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
void RigEllipsisTesselator::computeCirclePoints( size_t numSlices )
{
    // Based on GeometryUtils::generatePointsOnCircle

    double da = 2 * cvf::PI_D / numSlices;

    cvf::Vec3f point = cvf::Vec3f::ZERO;

    // Center of circle
    m_circlePoints.push_back( point );

    for ( size_t i = 0; i < numSlices; i++ )
    {
        // Precompute this one (A = i*da;)
        double sinA = cvf::Math::sin( i * da );
        double cosA = cvf::Math::cos( i * da );

        point.x() = static_cast<float>( -sinA );
        point.y() = static_cast<float>( cosA );

        m_circlePoints.push_back( point );
    }

    for ( cvf::uint i = 0; i < static_cast<cvf::uint>( numSlices ); i++ )
    {
        // Center
        m_circleConnectivities.push_back( 0 );

        m_circleConnectivities.push_back( i + 1 );

        if ( i == ( numSlices - 1 ) )
        {
            // Connect the last slice to the first slice
            m_circleConnectivities.push_back( 1 );
        }
        else
        {
            m_circleConnectivities.push_back( i + 2 );
        }
    }
}