这在 Canvas3D 中可以正常工作，但在 QQuickFramebufferObject 中不行。
我的代码
我的测试用例基于与 Qt 捆绑的 textureinsgnode 示例应用程序。由于我的作品是衍生作品，我必须先在此处发布许可条款：
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现在是实际来源。
主.cpp：
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QOpenGLFramebufferObject>
#include <QSGTextureProvider>
#include <QQuickFramebufferObject>
#include <QOpenGLShaderProgram>
#include <QOpenGLFunctions>
#include <QQuickWindow>
// propertyhelper.h is taken from http://syncor.blogspot.bg/2014/11/qt-auto-property.html
#include "propertyhelper.h"
class MyItem : public QQuickFramebufferObject {
Q_OBJECT
AUTO_PROPERTY(QQuickItem*, sourceItem)
public:
Renderer *createRenderer() const;
};
class MyItemRenderer : public QQuickFramebufferObject::Renderer, protected QOpenGLFunctions {
public:
MyItemRenderer() {
initializeOpenGLFunctions();
m_program.addShaderFromSourceCode(QOpenGLShader::Vertex,
"attribute highp vec4 aPos;"
"attribute highp vec2 aTexCoord;"
"varying mediump vec2 vTexCoord;"
""
"void main() {"
" gl_Position = aPos;"
" vTexCoord = aTexCoord;"
"}");
m_program.addShaderFromSourceCode(QOpenGLShader::Fragment,
"varying mediump vec2 vTexCoord;"
"uniform sampler2D uTex;"
""
"void main() {"
" gl_FragColor = texture2D(uTex, vTexCoord);"
"}");
m_program.link();
m_program.bind();
// Setup texture sampler uniform
glActiveTexture(GL_TEXTURE0);
m_program.setUniformValue("uTex", 0);
createGeometry();
}
void render() {
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClear(GL_COLOR_BUFFER_BIT);
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
m_program.bind();
m_tex->bind();
paintGeometry();
m_window->resetOpenGLState();
update();
}
void paintGeometry() {
m_program.enableAttributeArray("aPos");
m_program.enableAttributeArray("aTexCoord");
m_program.setAttributeArray("aPos", m_vertices.constData());
m_program.setAttributeArray("vTexCoord", m_texCoords.constData());
glDrawArrays(GL_TRIANGLES, 0, m_vertices.size());
m_program.disableAttributeArray("aPos");
m_program.disableAttributeArray("aTexCoord");
}
QOpenGLFramebufferObject *createFramebufferObject(const QSize &size) {
QOpenGLFramebufferObjectFormat format;
format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
return new QOpenGLFramebufferObject(size, format);
}
protected:
void synchronize(QQuickFramebufferObject* qqfbo) {
MyItem* parentItem = (MyItem*)qqfbo;
QQuickItem* sourceItem = parentItem->sourceItem();
QQuickItem* texSource = sourceItem->childItems()[0];
QSGTextureProvider* texProvider = texSource->textureProvider();
m_tex = texProvider->texture();
m_window = parentItem->window();
}
private:
QVector<QVector3D> m_vertices;
QVector<QVector2D> m_texCoords;
QOpenGLShaderProgram m_program;
QSGTexture* m_tex;
QQuickWindow* m_window;
void createGeometry() {
m_vertices << QVector3D(0, 0, 0.0f);
m_vertices << QVector3D(1, 0, 0.0f);
m_vertices << QVector3D(0, 1, 0.0f);
m_texCoords << QVector2D(0, 0);
m_texCoords << QVector2D(1, 0);
m_texCoords << QVector2D(0, 1);
}
};
QQuickFramebufferObject::Renderer *MyItem::createRenderer() const {
return new MyItemRenderer();
}
int main(int argc, char **argv) {
QGuiApplication app(argc, argv);
qmlRegisterType<MyItem>("MyItem", 1, 0, "MyItem");
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
return app.exec();
}
#include "main.moc"
main.qml：
import QtQuick 2.0
import MyItem 1.0
import QtQuick.Window 2.2
Window {
visible: true
width: 400
height: 400
Rectangle {
anchors.fill: parent
color: "lightblue"
}
Item {
id: test
// visible: false
Text {
layer.enabled: true
font.pointSize: 30
text: "hello\nhello\nhello"
}
}
MyItem {
anchors.fill: parent
sourceItem: test
}
}
如果取消注释visible: falsein main.qml，QQFBO 将停止显示任何内容。为什么会这样，什么是适当的解决方案？
我试过设置opacity: 0而不是，visible: false但这会导致同样的问题。
我尝试用 替换layer: true一个单独的ShaderEffectSource元素hideSource: true，但是我必须在visible: false上设置ShaderEffectSource，这会导致同样的问题。
我也尝试过设置x: -10000; y: -10000而不是，visible: false它工作正常，但它是一个黑客。