/*
 *  SPDX-FileCopyrightText: 2014 Andreas Cord-Landwehr <cordlandwehr@kde.org>
 *
 *  SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
 */

#include "qsgarrowheadnode.h"
#include <QColor>
#include <QSGGeometry>

using namespace GraphTheory;

QSGArrowHeadNode::QSGArrowHeadNode()
    : m_geometry(QSGGeometry::defaultAttributes_Point2D(), 3)
{
    m_material.setColor(QColor(0, 0, 0));
    setMaterial(&m_material);

    setGeometry(&m_geometry);
    m_geometry.setDrawingMode(GL_TRIANGLES);
}

QSGArrowHeadNode::~QSGArrowHeadNode()
{
}

void QSGArrowHeadNode::setArrow(const QPointF &from, const QPointF &to)
{
    const qreal baseSize = 6;
    const qreal padding = 8; // distance from head to node center

    // compute main axis of head
    QVector2D normale(to - from);
    normale.normalize();
    normale = normale * baseSize;

    // compute orthogonal line: switch x and y coefficients and change the sign of one
    QVector2D halfBaseLine(normale.y(), -normale.x());

    // make computations obvious
    const QVector2D paddingVec(normale * padding / normale.length());
    const QPointF A(to - paddingVec.toPointF());
    const QPointF B(to - paddingVec.toPointF() - 3 * normale.toPointF() + halfBaseLine.toPointF());
    const QPointF C(to - paddingVec.toPointF() - 3 * normale.toPointF() - halfBaseLine.toPointF());

    m_geometry.vertexDataAsPoint2D()[0].set(A.x(), A.y()); // pointy end
    m_geometry.vertexDataAsPoint2D()[1].set(B.x(), B.y()); // left bottom
    m_geometry.vertexDataAsPoint2D()[2].set(C.x(), C.y()); // right bottom

    markDirty(QSGNode::DirtyGeometry);
}

void QSGArrowHeadNode::setColor(const QColor &color)
{
    QSGFlatColorMaterial *m = static_cast<QSGFlatColorMaterial *>(material());
    m->setColor(color);
    markDirty(QSGNode::DirtyMaterial);
}
