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#include <QtCore>
#include <QtGui>
#include <QtWidgets>
void nativePainting()
{
static const float vertexPositions[] = {
-0.8f, -0.8f, 0.0f,
0.8f, -0.8f, 0.0f,
0.0f, 0.8f, 0.0f
};
static const float vertexColors[] = {
1.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 1.0f
};
QOpenGLBuffer vertexPositionBuffer(QOpenGLBuffer::VertexBuffer);
vertexPositionBuffer.create();
vertexPositionBuffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
vertexPositionBuffer.bind();
vertexPositionBuffer.allocate(vertexPositions, 9 * sizeof(float));
QOpenGLBuffer vertexColorBuffer(QOpenGLBuffer::VertexBuffer);
vertexColorBuffer.create();
vertexColorBuffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
vertexColorBuffer.bind();
vertexColorBuffer.allocate(vertexColors, 9 * sizeof(float));
QOpenGLShaderProgram program;
program.addShaderFromSourceCode(QOpenGLShader::Vertex,
"#version 330\n"
"in vec3 position;\n"
"in vec3 color;\n"
"out vec3 fragColor;\n"
"void main() {\n"
" fragColor = color;\n"
" gl_Position = vec4(position, 1.0);\n"
"}\n"
);
program.addShaderFromSourceCode(QOpenGLShader::Fragment,
"#version 330\n"
"in vec3 fragColor;\n"
"out vec4 color;\n"
"void main() {\n"
" color = vec4(fragColor, 1.0);\n"
"}\n"
);
program.link();
program.bind();
vertexPositionBuffer.bind();
program.enableAttributeArray("position");
program.setAttributeBuffer("position", GL_FLOAT, 0, 3);
vertexColorBuffer.bind();
program.enableAttributeArray("color");
program.setAttributeBuffer("color", GL_FLOAT, 0, 3);
glDrawArrays(GL_TRIANGLES, 0, 3);
}
QImage createImageWithFBO()
{
QSurfaceFormat format;
// format.setMajorVersion(3); ios 下注释
// format.setMinorVersion(3); iOS 下注释
QWindow window;
window.setSurfaceType(QWindow::OpenGLSurface);
window.setFormat(format);
window.create();
QOpenGLContext context;
context.setFormat(format);
if (!context.create())
qFatal("Cannot create the requested OpenGL context!");
context.makeCurrent(&window);
const QRect drawRect(0, 0, 400, 400);
const QSize drawRectSize = drawRect.size();
QOpenGLFramebufferObjectFormat fboFormat;
fboFormat.setSamples(16);
fboFormat.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
QOpenGLFramebufferObject fbo(drawRectSize, fboFormat);
fbo.bind();
QOpenGLPaintDevice device(drawRectSize);
QPainter painter;
painter.begin(&device);
painter.setRenderHints(QPainter::Antialiasing | QPainter::HighQualityAntialiasing);
painter.fillRect(drawRect, Qt::blue);
painter.drawTiledPixmap(drawRect, QPixmap(":/qt-project.org/qmessagebox/images/qtlogo-64.png"));
painter.setPen(QPen(Qt::green, 5));
painter.setBrush(Qt::red);
painter.drawEllipse(0, 100, 400, 200);
painter.drawEllipse(100, 0, 200, 400);
painter.beginNativePainting();
nativePainting();
painter.endNativePainting();
painter.setPen(QPen(Qt::white, 0));
QFont font;
font.setPointSize(24);
painter.setFont(font);
painter.drawText(drawRect, "Hello FBO", QTextOption(Qt::AlignCenter));
painter.end();
fbo.release();
return fbo.toImage();
}
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QImage targetImage = createImageWithFBO();
QLabel label;
label.setPixmap(QPixmap::fromImage(targetImage));
label.show();
return app.exec();
}