QCustom3DItem自发光

QCustom3DItem可以通过添加自定义的材质来实现自发光效果。以下是一些实现自发光效果的步骤：

1. 创建自定义的材质类，并从QPhongMaterial继承，例如QCustomGlowMaterial。

2. 在QCustomGlowMaterial类中，重写createEffect()方法，该方法创建一个QEffect对象，该对象用于处理自发光效果。

3. 在createEffect()方法中，创建一个QLightEmission实例，并将其添加到QEffect中。

4. 将QCustomGlowMaterial应用于QCustom3DItem的外观，以实现自发光效果。

以下是一个简单的例子，该例子演示了如何使用自定义的材质来实现QCustom3DItem的自发光效果：

class QCustomGlowMaterial : public Qt3DRender::QPhongMaterial
{
public:
    QCustomGlowMaterial(Qt3DCore::QNode *parent = nullptr)
        : QPhongMaterial(parent)
    {
    }

    Qt3DRender::QEffect *createEffect() const override
    {
        Qt3DRender::QEffect *effect = new Qt3DRender::QEffect;

        // Create a light emission instance
        Qt3DRender::QLightEmission *lightEmission = new Qt3DRender::QLightEmission;
        lightEmission->setColor(Qt::white);
        lightEmission->setIntensity(1.0f);

        // Add light emission to the effect
        Qt3DRender::QTechnique *technique = new Qt3DRender::QTechnique;
        Qt3DRender::QRenderPass *renderPass = new Qt3DRender::QRenderPass;
        renderPass->addRenderState(new Qt3DRender::QBlendEquationArguments(Qt3DRender::QBlendEquationArguments::Add,
                                                                           Qt3DRender::QBlendEquationArguments::One,
                                                                           Qt3DRender::QBlendEquationArguments::One));
        renderPass->addRenderState(new Qt3DRender::QDepthTest);
        renderPass->addRenderState(new Qt3DRender::QDepthMask(false));
        renderPass->addRenderState(new Qt3DRender::QColorMask(Qt::allChannels()));
        renderPass->addRenderState(new Qt3DRender::QAlphaTest);
        renderPass->addRenderState(new Qt3DRender::QCullFace);
        renderPass->addRenderState(new Qt3DRender::QNoDepthMask());
        renderPass->addRenderState(new Qt3DRender::QNoDepthTest());
        renderPass->addRenderState(new Qt3DRender::QNoCulling());
        renderPass->addRenderState(new Qt3DRender::QShaderProgram);

        Qt3DRender::QShaderProgram *shaderProgram = new Qt3DRender::QShaderProgram;
        shaderProgram->setVertexShaderCode(Qt3DRender::QShaderProgram::loadSource(QUrl(QStringLiteral("qrc:/shaders/passthrough.vert"))));
        shaderProgram->setFragmentShaderCode(Qt3DRender::QShaderProgram::loadSource(QUrl(QStringLiteral("qrc:/shaders/light_emission.frag"))));
        renderPass->setShaderProgram(shaderProgram);

        technique->addRenderPass(renderPass);
        technique->graphicsApiFilter()->setApi(Qt3DRender::QGraphicsApiFilter::OpenGL);
        technique->graphicsApiFilter()->setProfile(Qt3DRender::QGraphicsApiFilter::CoreProfile);

        effect->addTechnique(technique);
        effect->addParameter(lightEmission);

        return effect;
    }
};

// Create a QCustom3DItem and set its material to a custom glow material
Qt3DCore::QEntity *customItemEntity = new Qt3DCore::QEntity();
QCustom3DItem *customItem = new QCustom3DItem();
QCustomGlowMaterial *glowMaterial = new QCustomGlowMaterial();
customItem->setMaterial(glowMaterial);
customItemEntity->addComponent(customItem);

在这个例子中，我们创建了一个名为QCustomGlowMaterial的自定义材质，该材质继承自QPhongMaterial，并重写了createEffect()方法来实现自发光效果。我们还创建了一个QLightEmission实例，将其添加到QEffect中，并将其作为参数传递给效果。最后，我们创建了一个QCustom3DItem实例，将其材质设置为QCustomGlowMaterial，并将其添加到实体中。