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#include "qxclipnode_p.h"
#include "utilities.h"

#include <QtGui/QVector2D>
#include <QtCore/qmath.h>

QxClipNode::QxClipNode(const QRectF &rect)
: m_rect(rect), m_radius(0)
{
    updateGeometryDescription(Utilities::getRectGeometryDescription(), GL_UNSIGNED_SHORT);
    Utilities::setupRectGeometry(geometry(), m_rect);
    setFlag(ClipIsRectangular, true);
}

void QxClipNode::setRect(const QRectF &rect)
{
    m_rect = rect;
    setUpdateFlag(UpdateGeometry);
}

void QxClipNode::setRadius(qreal radius)
{
    m_radius = radius;
    setUpdateFlag(UpdateGeometry);
    setFlag(ClipIsRectangular, radius == 0);
}

void QxClipNode::update(uint updateFlags)
{
    if (updateFlags & UpdateGeometry)
        updateGeometry();
}

void QxClipNode::updateGeometry()
{
    if (qFuzzyIsNull(m_radius)) {
        updateGeometryDescription(Utilities::getRectGeometryDescription(), GL_UNSIGNED_SHORT);
        Utilities::setupRectGeometry(geometry(), m_rect);
    } else {
        struct Vertex
        {
            QVector2D position;
        };

        Geometry *g = geometry();
        int vertexCount = 0;

        // Radius should never exceeds half of the width or half of the height
        qreal radius = qMin(qMin(m_rect.width() / 2, m_rect.height() / 2), m_radius);
        QRectF rect = m_rect;
        rect.adjust(radius, radius, -radius, -radius);

        int segments = qMin(30, qCeil(radius)); // Number of segments per corner.

        // Overestimate the number of vertices and indices, reduce afterwards when the actual numbers are known.
        g->setVertexCount((segments + 1) * 4);
        g->setIndexCount(0);

        Vertex *vertices = (Vertex *)g->vertexData();

        for (int part = 0; part < 2; ++part) {
            for (int i = 0; i <= segments; ++i) {
                //### Should change to calculate sin/cos only once.
                qreal angle = qreal(0.5 * M_PI) * (part + i / qreal(segments));
                qreal s = qFastSin(angle);
                qreal c = qFastCos(angle);
                qreal y = (part ? rect.bottom() : rect.top()) - radius * c; // current inner y-coordinate.
                qreal lx = rect.left() - radius * s; // current inner left x-coordinate.
                qreal rx = rect.right() + radius * s; // current inner right x-coordinate.

                vertices[vertexCount++].position = QVector2D(rx, y);
                vertices[vertexCount++].position = QVector2D(lx, y);
            }
        }

        g->setDrawingMode(QGL::TriangleStrip);
        g->setVertexCount(vertexCount);

        markDirty(DirtyGeometry);
    }
    setBoundingRect(m_rect);
}