simplematerial.cpp Example File | Qt Quick 5.12.5

Qt 5.12 | Qt Quick | Scene Graph - Simple Material | simplematerial.cpp Example File

Qt 5.12.5 Reference Documentation

# simplematerial.cpp Example File

scenegraph/simplematerial/simplematerial.cpp

      /****************************************************************************
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      #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 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"
                      "}";
          }
          QList<QByteArray> attributes() const override
          {
              return QList<QByteArray>() << "aVertex" << "aTexCoord";
          }
          void updateState(const State *state, const State *) override
          {
              program()->setUniformValue(id_color, state->color);
          }
          void resolveUniforms() override
          {
              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 *) override
          {
              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"