#include "glsphere.h"

GLSphere::GLSphere(double radius, int stacks, int slices)
    : GLBody(radius)
{
    m_stacks = stacks * 2 / 2;
    m_slices = slices * 2 / 2;
}

void GLSphere::makeSurface(QVector<GLPoint> *pointContainer,
                           QVector<GLshort> *indexContainer)
{
    GLBody::makeSurface(pointContainer, indexContainer);

    QVector3D t0 = QVector3D(0.0, 0.0, 0.0); //dummy texture

    QVector3D northpol = v_Y;
    QVector3D southpol = -v_Y;

    QVector3D tmpPoint;

    m_firstPoint = m_points->size();

    m_points->append(GLPoint(m_radius * northpol, northpol, t0, m_color));

    for (int slice = 0; slice < m_slices; slice++)
    {
        for (int stack = 1; stack < m_stacks; stack++)
        {
            tmpPoint = calculatePoint(2 * M_PI * slice / m_slices, stack * M_PI / m_stacks);
            m_points->append(GLPoint(m_radius * tmpPoint, tmpPoint, t0, m_color));
        }
    }

    m_points->append(GLPoint(m_radius * southpol, southpol, t0, m_color));

    m_nextPoint = m_points->size();

    m_firstIndex = m_indices->size();

    for (int slice = 1; slice < m_slices - 1; slice += 2)
    {
        m_indices->append(m_firstPoint);

        for (int stack = 0; stack < m_stacks - 1; stack++)
        {
            m_indices->append((m_firstPoint + 1) + stack + ((m_stacks - 1) * (slice - 1)));
            m_indices->append((m_firstPoint + 1) + stack + ((m_stacks - 1) * slice));
        }

        m_indices->append(m_nextPoint - 1);

        for (int stack = m_stacks - 2; stack >= 0; stack--)
        {
            m_indices->append((m_firstPoint + 1) + stack + ((m_stacks - 1) * (slice + 1)));
            m_indices->append((m_firstPoint + 1) + stack + ((m_stacks - 1) * slice));
        }

        m_indices->append(m_firstPoint);
    }

    m_nextIndex = m_indices->size();
}

QVector3D GLSphere::calculatePoint(double sliceRotation, double stackRotation)
{
    double x = sin(stackRotation) * sin(sliceRotation);
    double y = cos(stackRotation);
    double z = sin(stackRotation) * cos(sliceRotation);

    return QVector3D(x, y, z);
}