kicad/3d-viewer/3d_rendering/3d_render_raytracing/shapes2D/ring_2d.cpp

/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2015-2016 Mario Luzeiro <mrluzeiro@ua.pt>
 * Copyright (C) 1992-2020 KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

/**
 * @file ring_2d.cpp
 */

#include "ring_2d.h"
#include "../../../3d_fastmath.h"
#include "../ray.h"
#include <wx/debug.h>


RING_2D::RING_2D( const SFVEC2F& aCenter, float aInnerRadius, float aOuterRadius,
                  const BOARD_ITEM& aBoardItem ) :
        OBJECT_2D( OBJECT_2D_TYPE::RING, aBoardItem )
{
    wxASSERT( aInnerRadius < aOuterRadius );

    m_center = aCenter;
    m_inner_radius = aInnerRadius;
    m_outer_radius = aOuterRadius;

    m_inner_radius_squared = aInnerRadius * aInnerRadius;
    m_outer_radius_squared = aOuterRadius * aOuterRadius;

    m_bbox.Reset();
    m_bbox.Set( m_center - SFVEC2F( aOuterRadius, aOuterRadius ),
                m_center + SFVEC2F( aOuterRadius, aOuterRadius ) );
    m_bbox.ScaleNextUp();
    m_centroid = m_bbox.GetCenter();

    wxASSERT( m_bbox.IsInitialized() );
}


bool RING_2D::Overlaps( const BBOX_2D& aBBox ) const
{
    // NOT IMPLEMENTED, why?
    return false;
}


bool RING_2D::Intersects( const BBOX_2D& aBBox ) const
{
    // !TODO: check the inside for a great improvement
    return aBBox.Intersects( m_center, m_outer_radius_squared );
}


bool RING_2D::Intersect( const RAYSEG2D& aSegRay, float* aOutT, SFVEC2F* aNormalOut ) const
{
    // This code used directly from Steve Marschner's CS667 framework
    // http://cs665pd.googlecode.com/svn/trunk/photon/sphere.cpp

    // Compute some factors used in computation
    const float qx = ( aSegRay.m_Start.x - m_center.x );
    const float qy = ( aSegRay.m_Start.y - m_center.y );

    const float qd = qx * aSegRay.m_Dir.x + qy * aSegRay.m_Dir.y;
    const float qq = qx * qx + qy * qy;

    // solving the quadratic equation for t at the pts of intersection
    // dd*t^2 + (2*qd)*t + (qq-r^2) = 0
    const float discriminantsqr = qd * qd - qq;
    const float discriminantsqr_outer = discriminantsqr + m_outer_radius_squared;

    // If the discriminant is less than zero, there is no intersection
    if( discriminantsqr_outer < FLT_EPSILON )
        return false;

    // Otherwise check and make sure that the intersections occur on the ray (t
    // > 0) and return the closer one
    const float discriminant = sqrt( discriminantsqr_outer );
    float       t = ( -qd - discriminant );

    if( ( t > FLT_EPSILON ) && ( t < aSegRay.m_Length ) )
    {
        if( aNormalOut )
        {
            SFVEC2F hitPoint = aSegRay.at( t );
            *aNormalOut = (hitPoint - m_center) / m_outer_radius;
        }
    }
    else
    {
        const float discriminantsqr_inter = discriminantsqr + m_inner_radius_squared;

        if( discriminantsqr_inter > FLT_EPSILON )
        {
            const float discriminant_inner = sqrt( discriminantsqr_inter );

            const float t2_inner = ( -qd + discriminant_inner );

            if( ( t2_inner > FLT_EPSILON ) && ( t2_inner < aSegRay.m_Length ) )
            {
                t = t2_inner;

                if( aNormalOut )
                {
                    const SFVEC2F hitPoint = aSegRay.at( t2_inner );

                    *aNormalOut = ( m_center - hitPoint ) / m_inner_radius;
                }
            }
            else
            {
                return false;
            }
        }
        else
        {
            return false;
        }
    }

    wxASSERT( (t > 0.0f) && (t <= aSegRay.m_Length) );

    // Convert the intersection to a normalized 0.0 .. 1.0
    if( aOutT )
        *aOutT = t / aSegRay.m_Length;

    return true;
}


INTERSECTION_RESULT RING_2D::IsBBoxInside( const BBOX_2D& aBBox ) const
{
    return INTERSECTION_RESULT::MISSES;
}


bool RING_2D::IsPointInside( const SFVEC2F& aPoint ) const
{
    const SFVEC2F v = m_center - aPoint;

    const float dot = glm::dot( v, v );

    if( ( dot <= m_outer_radius_squared ) && ( dot >= m_inner_radius_squared ) )
        return true;

    return false;
}