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#include "simplematerialitem.h"

#include <QtQuick/qsgsimplematerial.h>
#include <QtQuick/qsggeometry.h>
#include <QtQuick/qsgnode.h>

//! [1]
struct State
{
    QColor color;

    int compare(const State *other) const {
        uint rgb = color.rgba();
        uint otherRgb = other->color.rgba();

        if (rgb == otherRgb) {
            return 0;
        } else if (rgb < otherRgb) {
            return -1;
        } else {
            return 1;
        }
    }
};
//! [1]

//! [2]
class Shader : public QSGSimpleMaterialShader<State>
{
    QSG_DECLARE_SIMPLE_COMPARABLE_SHADER(Shader, State);
//! [2] //! [3]
public:

    const char *vertexShader() const override {
        return
                "attribute highp vec4 aVertex;                              \n"
                "attribute highp vec2 aTexCoord;                            \n"
                "uniform highp mat4 qt_Matrix;                              \n"
                "varying highp vec2 texCoord;                               \n"
                "void main() {                                              \n"
                "    gl_Position = qt_Matrix * aVertex;                     \n"
                "    texCoord = aTexCoord;                                  \n"
                "}";
    }

    const char *fragmentShader() const override {
        return
                "uniform lowp float qt_Opacity;                             \n"
                "uniform lowp vec4 color;                                   \n"
                "varying highp vec2 texCoord;                               \n"
                "void main ()                                               \n"
                "{                                                          \n"
                "    gl_FragColor = texCoord.y * texCoord.x * color * qt_Opacity;  \n"
                "}";
    }
//! [3] //! [4]
    QList<QByteArray> attributes() const override
    {
        return QList<QByteArray>() << "aVertex" << "aTexCoord";
    }
//! [4] //! [5]
    void updateState(const State *state, const State *) override
    {
        program()->setUniformValue(id_color, state->color);
    }
//! [5] //! [6]
    void resolveUniforms() override
    {
        id_color = program()->uniformLocation("color");
    }

private:
    int id_color;
//! [6]
};


//! [7]
class ColorNode : public QSGGeometryNode
{
public:
    ColorNode()
        : m_geometry(QSGGeometry::defaultAttributes_TexturedPoint2D(), 4)
    {
        setGeometry(&m_geometry);

        QSGSimpleMaterial<State> *material = Shader::createMaterial();
        material->setFlag(QSGMaterial::Blending);
        setMaterial(material);
        setFlag(OwnsMaterial);
    }

    QSGGeometry m_geometry;
};
//! [7]

void SimpleMaterialItem::setColor(const QColor &color) {
    if (m_color != color) {
        m_color = color;
        emit colorChanged();
        update();
    }
}

//! [9]
QSGNode *SimpleMaterialItem::updatePaintNode(QSGNode *node, QQuickItem::UpdatePaintNodeData *)
{
    ColorNode *n = static_cast<ColorNode *>(node);
    if (!node)
        n = new ColorNode();

    QSGGeometry::updateTexturedRectGeometry(n->geometry(), boundingRect(), QRectF(0, 0, 1, 1));
    static_cast<QSGSimpleMaterial<State>*>(n->material())->state()->color = m_color;

    n->markDirty(QSGNode::DirtyGeometry | QSGNode::DirtyMaterial);

    return n;
}
//! [9]