source: projectionDesigner/trunk/projdesigner/src/math/ProjectionMatrix.cpp @ 108

#include "math/ProjectionMatrix.h"

using namespace projection;
using namespace gmtl;

/**
 * Constructor.
 *
 * Default projection matrix value is : FOV=30.0, 
 * AspectRatio=4/3, Near=0.1, Far=100.0
 */
ProjectionMatrix::ProjectionMatrix()
{
    m_fov = 30.0f;
    m_aspectRatio = 1024.0f / 768.0f;
    m_near = 0.1f;
    m_far = 100.0f;
    m_offaxisX = 0.0f;
    m_offaxisY = 0.0f;
}

/**
 * Destructor.
 */
ProjectionMatrix::~ProjectionMatrix()
{
}

/**
 * Copy constructor.
 *
 * @param matrix Copy source matrix.
 */
ProjectionMatrix::ProjectionMatrix(const ProjectionMatrix &matrix)
{
    m_fov = matrix.getFOV();
    m_aspectRatio = matrix.getAspectRatio();
    m_near = matrix.getNear();
    m_far = matrix.getFar();
    m_offaxisX = matrix.getOffaxisX();
    m_offaxisY = matrix.getOffaxisY();
}

/**
 * Retrieve matrix values for glMultMatrixd().
 *
 * @return Matrix values.
 */
float* ProjectionMatrix::getMatrix()
{
    // glMultMatrixd(getMatrix()) is same as glFrustum().
    float left =   (-tanf(Math::deg2Rad(m_fov) / 2.0f * m_aspectRatio) - m_offaxisX) * m_near;
    float right =  ( tanf(Math::deg2Rad(m_fov) / 2.0f * m_aspectRatio) - m_offaxisX) * m_near;
    float top =    ( tanf(Math::deg2Rad(m_fov) / 2.0f) + m_offaxisY) * m_near;
    float bottom = (-tanf(Math::deg2Rad(m_fov) / 2.0f) + m_offaxisY) * m_near;
    m_mat[ 0] = (2.0f * m_near) / (right - left);
    m_mat[ 1] = 0.0f;
    m_mat[ 2] = 0.0f;
    m_mat[ 3] = 0.0f;
    m_mat[ 4] = 0.0f;
    m_mat[ 5] = (2.0f * m_near) / (top - bottom);
    m_mat[ 6] = 0.0f;
    m_mat[ 7] = 0.0f;
    m_mat[ 8] = (right + left) / (right - left);
    m_mat[ 9] = (top + bottom) / (top - bottom);
    m_mat[10] = -(m_far + m_near) / (m_far - m_near);
    m_mat[11] = -1.0f;
    m_mat[12] = 0.0f;
    m_mat[13] = 0.0f;
    m_mat[14] = -(2.0f * m_far * m_near) / (m_far - m_near);
    m_mat[15] = 0.0f;

    return m_mat;
}

/**
 * Retrieve four corner vectors.
 *
 * @param Four corner vectors.
 */
void ProjectionMatrix::getCorners(gmtl::Vec3f vecs[4]) const
{
    float left =   (-tanf(Math::deg2Rad(m_fov) / 2.0f * m_aspectRatio) + m_offaxisX);
    float right =  ( tanf(Math::deg2Rad(m_fov) / 2.0f * m_aspectRatio) + m_offaxisX);
    float top =    ( tanf(Math::deg2Rad(m_fov) / 2.0f) + m_offaxisY);
    float bottom = (-tanf(Math::deg2Rad(m_fov) / 2.0f) + m_offaxisY);
    vecs[0].set(left, 1.0f, top);
    vecs[1].set(right, 1.0f, top);
    vecs[2].set(right, 1.0f, bottom);
    vecs[3].set(left, 1.0f, bottom);
    normalize(vecs[0]);
    normalize(vecs[1]);
    normalize(vecs[2]);
    normalize(vecs[3]);
}

/**
 * Retrieve frustum parameters as 'Frustum left right bottom top near far;'.
 *
 * @param numSpaces Number of space characters for indent.
 * @return Frustum params.
 */
QString ProjectionMatrix::getParams(int numSpaces) const
{
    QString spc;
    spc.fill(' ', numSpaces);
    double left =   (-tan(Math::deg2Rad(m_fov) / 2.0 * m_aspectRatio) + m_offaxisX);
    double right =  ( tan(Math::deg2Rad(m_fov) / 2.0 * m_aspectRatio) + m_offaxisX);
    double top =    ( tan(Math::deg2Rad(m_fov) / 2.0) + m_offaxisY);
    double bottom = (-tan(Math::deg2Rad(m_fov) / 2.0) + m_offaxisY);
  return spc + QString("Frustum %1 %2 %3 %4 %5 %6;").arg(left*m_near).arg(right*m_near).arg(bottom*m_near).arg(top*m_near).arg(m_near).arg(m_far);
}

/**
 * Restore the projection matrix from XML data.
 *
 * @param element Parent XML element of the projection matrix data.
 */
void ProjectionMatrix::initFromDOMElement(const QDomElement& element)
{
        m_fov = element.attribute("fov").toFloat();
        m_aspectRatio = element.attribute("aspectRatio").toFloat();
        m_near = element.attribute("near").toFloat();
        m_far = element.attribute("far").toFloat();
        m_offaxisX = element.attribute("offaxisX").toFloat();
        m_offaxisY = element.attribute("offaxisY").toFloat();
}

/**
 * Store the current projection matrix as XML data.
 *
 * @param name XML node name of the data.
 * @param doc XML document to store the data.
 * @return Current screen shape data as XML data.
 */
QDomElement ProjectionMatrix::domElement(const QString& name, QDomDocument& doc) const
{
        QDomElement de = doc.createElement(name);

        de.setAttribute("fov", QString::number(m_fov));
        de.setAttribute("aspectRatio", QString::number(m_aspectRatio));
        de.setAttribute("near", QString::number(m_near));
        de.setAttribute("far", QString::number(m_far));
        de.setAttribute("offaxisX", QString::number(m_offaxisX));
        de.setAttribute("offaxisY", QString::number(m_offaxisY));

        return de;
}