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/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "linenode.h"

#include <QtGui/QColor>

#include <QtQuick/QSGMaterial>

class LineShader : public QSGMaterialShader
{
public:
    LineShader() {
        setShaderFileName(VertexStage, QLatin1String(":/scenegraph/graph/shaders/line.vert.qsb"));
        setShaderFileName(FragmentStage, QLatin1String(":/scenegraph/graph/shaders/line.frag.qsb"));
    }

    bool updateUniformData(RenderState &state, QSGMaterial *newMaterial, QSGMaterial *oldMaterial) override;
};

class LineMaterial : public QSGMaterial
{
public:
    LineMaterial()
    {
        setFlag(Blending);
    }

    QSGMaterialType *type() const override
    {
        static QSGMaterialType type;
        return &type;
    }

    QSGMaterialShader *createShader() const override
    {
        return new LineShader;
    }

    int compare(const QSGMaterial *m) const override
    {
        const LineMaterial *other = static_cast<const LineMaterial *>(m);

        if (int diff = int(state.color.rgb()) - int(other->state.color.rgb()))
            return diff;

        if (int diff = state.size - other->state.size)
            return diff;

        if (int diff = state.spread - other->state.spread)
            return diff;

        return 0;
    }

    struct {
        QColor color;
        float size;
        float spread;
    } state;
};

bool LineShader::updateUniformData(RenderState &state, QSGMaterial *newMaterial, QSGMaterial *)
{
    QByteArray *buf = state.uniformData();
    Q_ASSERT(buf->size() >= 92);

    if (state.isMatrixDirty()) {
        const QMatrix4x4 m = state.combinedMatrix();
        memcpy(buf->data(), m.constData(), 64);
    }

    if (state.isOpacityDirty()) {
        const float opacity = state.opacity();
        memcpy(buf->data() + 80, &opacity, 4);
    }

    LineMaterial *mat = static_cast<LineMaterial *>(newMaterial);
    float c[4] = { float(mat->state.color.redF()),
                   float(mat->state.color.greenF()),
                   float(mat->state.color.blueF()),
                   float(mat->state.color.alphaF()) };
    memcpy(buf->data() + 64, c, 16);
    memcpy(buf->data() + 84, &mat->state.size, 4);
    memcpy(buf->data() + 88, &mat->state.spread, 4);

    return true;
}

struct LineVertex {
    float x;
    float y;
    float t;
    inline void set(float xx, float yy, float tt) { x = xx; y = yy; t = tt; }
};

static const QSGGeometry::AttributeSet &attributes()
{
    static QSGGeometry::Attribute attr[] = {
        QSGGeometry::Attribute::create(0, 2, GL_FLOAT, true),
        QSGGeometry::Attribute::create(1, 1, GL_FLOAT)
    };
    static QSGGeometry::AttributeSet set = { 2, 3 * sizeof(float), attr };
    return set;
}

LineNode::LineNode(float size, float spread, const QColor &color)
    : m_geometry(attributes(), 0)
{
    setGeometry(&m_geometry);
    m_geometry.setDrawingMode(GL_TRIANGLE_STRIP);

    LineMaterial *m = new LineMaterial;
    m->state.color = color;
    m->state.size = size;
    m->state.spread = spread;

    setMaterial(m);
    setFlag(OwnsMaterial);
}

/*
 * Assumes that samples have values in the range of 0 to 1 and scales them to
 * the height of bounds. The samples are stretched out horizontally along the
 * width of the bounds.
 *
 * The position of each pair of points is identical, but we use the third value
 * "t" to shift the point up or down and to add antialiasing.
 */
void LineNode::updateGeometry(const QRectF &bounds, const QList<qreal> &samples)
{
    m_geometry.allocate(samples.size() * 2);

    float x = bounds.x();
    float y = bounds.y();
    float w = bounds.width();
    float h = bounds.height();

    float dx = w / (samples.size() - 1);

    LineVertex *v = (LineVertex *) m_geometry.vertexData();
    for (int i=0; i<samples.size(); ++i) {
        v[i*2+0].set(x + dx * i, y + samples.at(i) * h, 0);
        v[i*2+1].set(x + dx * i, y + samples.at(i) * h, 1);
    }

    markDirty(QSGNode::DirtyGeometry);
}