SectionLenticular.cpp

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/*=============================================================================
TexGen: Geometric textile modeller.
Copyright (C) 2006 Martin Sherburn
 
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, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
=============================================================================*/
 
#include "PrecompiledHeaders.h"
#include "SectionLenticular.h"
using namespace TexGen;
 
CSectionLenticular::CSectionLenticular(double dWidth, double dHeight, double dDistortion)
: m_dWidth(dWidth)
, m_dHeight(dHeight)
, m_dDistortion(dDistortion)
{
    if (dHeight > dWidth)
        TGERROR("Warning: Lenticular section has greater height than width");
    if (abs(dDistortion) > 0.5*dHeight+1e-9)
        TGERROR("Warning: Lenticular section distortion is greater than half the height");
}
 
CSectionLenticular::~CSectionLenticular(void)
{
}
 
bool CSectionLenticular::operator == (const CSection &CompareMe) const
{
    if (CompareMe.GetType() != GetType())
        return false;
    return m_dWidth == ((CSectionLenticular*)&CompareMe)->m_dWidth &&
        m_dHeight == ((CSectionLenticular*)&CompareMe)->m_dHeight &&
        m_dDistortion == ((CSectionLenticular*)&CompareMe)->m_dDistortion;
}
 
CSectionLenticular::CSectionLenticular(TiXmlElement &Element)
: CSection(Element)
, m_dWidth(0)
, m_dHeight(0)
, m_dDistortion(0)
{
    // For backwards compatibility, previously lenticular shapes could
    // not be distorted
    if (Element.Attribute("Radius") && Element.Attribute("Offset"))
    {
        double dRadius, dOffset;
        Element.Attribute("Radius", &dRadius);
        Element.Attribute("Offset", &dOffset);
        m_dWidth = 2*sqrt(dRadius*dRadius-dOffset*dOffset);
        m_dHeight = 2*(dRadius-dOffset);
        m_dDistortion = 0;
    }
    else
    {
        Element.Attribute("Width", &m_dWidth);
        Element.Attribute("Height", &m_dHeight);
        Element.Attribute("Distortion", &m_dDistortion);
    }
}
 
void CSectionLenticular::PopulateTiXmlElement(TiXmlElement &Element, OUTPUT_TYPE OutputType) const
{
    CSection::PopulateTiXmlElement(Element, OutputType);
    Element.SetAttribute("Width", stringify(m_dWidth));
    Element.SetAttribute("Height", stringify(m_dHeight));
    Element.SetAttribute("Distortion", stringify(m_dDistortion));
}
 
XY CSectionLenticular::GetPoint(double t) const
{
    XY Point;
    double dH;
    double dRadius;
    double dO;
    double dMaxAngle;
    double dAngle;
 
    if (t < 0.5)
        dH = m_dHeight-2*m_dDistortion;
    else
        dH = m_dHeight+2*m_dDistortion;
 
    if (abs(dH) < 1e-9)
    {
        if (t < 0.5)
        {
            Point.x = 0.5*m_dWidth-2*t*m_dWidth;
            Point.y = 0.5*m_dHeight;
        }
        else
        {
            Point.x = 0.5*m_dWidth-2*(1-t)*m_dWidth;
            Point.y = -0.5*m_dHeight;
        }
    }
    else
    {
        dRadius = (m_dWidth*m_dWidth + dH*dH) / (4*dH);
        dO = dRadius-0.5*m_dHeight;
        dMaxAngle = asin(0.5*m_dWidth/dRadius);
 
        if (t < 0.5)
        {
            dAngle = (1-4*t)*dMaxAngle;
            Point.x = dRadius*sin(dAngle);
            Point.y = dRadius*cos(dAngle)-dO;
        }
        else
        {
            dAngle = (-3+4*t)*dMaxAngle;
            Point.x = dRadius*sin(dAngle);
            Point.y = -(dRadius*cos(dAngle)-dO);
        }
    }
 
    return Point;
}
 
string CSectionLenticular::GetDefaultName() const
{
     return "Lenticular(W:" + stringify(m_dWidth) + ",H:" + stringify(m_dHeight) + ",D:" + stringify(m_dDistortion) + ")";
}