- Qt 5.5
- Qt Quick
- Scene Graph - Simple Material
- simplematerial.cpp Example File
- Qt 5.5.1 Reference Documentation

# simplematerial.cpp Example File

scenegraph/simplematerial/simplematerial.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** 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
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    ** information use the contact form at http://www.qt.io/contact-us.
    **
    ** GNU Lesser General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU Lesser
    ** General Public License version 2.1 or version 3 as published by the Free
    ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
    ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
    ** following information to ensure the GNU Lesser General Public License
    ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
    ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
    **
    ** As a special exception, The Qt Company gives you certain additional
    ** rights. These rights are described in The Qt Company LGPL Exception
    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include <qguiapplication.h>

    #include <qsgmaterial.h>
    #include <qsgnode.h>

    #include <qquickitem.h>
    #include <qquickview.h>

    #include <qsgsimplerectnode.h>

    #include <qsgsimplematerial.h>

    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;
            }
        }
    };

    class Shader : public QSGSimpleMaterialShader<State>
    {
        QSG_DECLARE_SIMPLE_COMPARABLE_SHADER(Shader, State);
    public:

        const char *vertexShader() const {
            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 {
            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"
                    "}";
        }
        QList<QByteArray> attributes() const
        {
            return QList<QByteArray>() << "aVertex" << "aTexCoord";
        }
        void updateState(const State *state, const State *)
        {
            program()->setUniformValue(id_color, state->color);
        }
        void resolveUniforms()
        {
            id_color = program()->uniformLocation("color");
        }

    private:
        int id_color;
    };

    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;
    };

    class Item : public QQuickItem
    {
        Q_OBJECT

        Q_PROPERTY(QColor color READ color WRITE setColor NOTIFY colorChanged)

    public:

        Item()
        {
            setFlag(ItemHasContents, true);
        }

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

    signals:
        void colorChanged();

    private:
      QColor m_color;

    public:
        QSGNode *updatePaintNode(QSGNode *node, 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;
        }
    };
    int main(int argc, char **argv)
    {
        QGuiApplication app(argc, argv);

        qmlRegisterType<Item>("SimpleMaterial", 1, 0, "SimpleMaterialItem");

        QQuickView view;
        view.setResizeMode(QQuickView::SizeRootObjectToView);
        view.setSource(QUrl("qrc:///scenegraph/simplematerial/main.qml"));
        view.show();

        return app.exec();
    }

    #include "simplematerial.moc"