我想在QOpenGLWidget上绘制文字标签。我尝试使用QPainter执行此任务,但没有成功 - 文本看起来很丑陋而且没有抗锯齿。在Qt OpenGL / 2dpainting样本中看起来也很丑陋。然而,在使用OpenGL后端的QML控件中,文本呈现明显更好。这里http://blog.qt.io/blog/2011/07/15/text-rendering-in-the-qml-scene-graph/我发现了一种在QML中使用的技术。有没有办法使用该技术在QOpenGLWidget中绘制文本?
PS:可能是正确的方法是将我的所有场景嵌入到QQuickWidget的QSGSceneGraph中?答案 0 :(得分:2)
确保使用支持多重采样以进行抗锯齿的表面格式创建QGL / QopenGLWidget:
QSurfaceFormat format = QSurfaceFormat::defaultFormat();
format.setSamples(4);
QOpenGLWidget * glWidget = new QOpenGLWidget;
glWidget->setFormat(format);
然后,在该窗口小部件上使用QPainter时,请确保打开抗锯齿:
QPainter painter(paintDevice);
painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
然后画出你的文字。
答案 1 :(得分:1)
重新实现旧的QOGLWidget的renderText()以方便文本呈现。 这样文本将随场景移动。如果您想要静态版本,可以简化它。
使用以下方法从QOpenGLWidget(在此示例中为GLBox)中继承一个类:
renderText:
void GLBox::renderText(D3DVECTOR &textPosWorld, QString text)
{
int width = this->width();
int height = this->height();
GLdouble model[4][4], proj[4][4];
GLint view[4];
glGetDoublev(GL_MODELVIEW_MATRIX, &model[0][0]);
glGetDoublev(GL_PROJECTION_MATRIX, &proj[0][0]);
glGetIntegerv(GL_VIEWPORT, &view[0]);
GLdouble textPosX = 0, textPosY = 0, textPosZ = 0;
project(textPosWorld.x, textPosWorld.y, textPosWorld.z,
&model[0][0], &proj[0][0], &view[0],
&textPosX, &textPosY, &textPosZ);
textPosY = height - textPosY; // y is inverted
QPainter painter(this);
painter.setPen(Qt::yellow);
painter.setFont(QFont("Helvetica", 8));
painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
painter.drawText(textPosX, textPosY, text); // z = pointT4.z + distOverOp / 4
painter.end();
}
项目:
inline GLint GLBox::project(GLdouble objx, GLdouble objy, GLdouble objz,
const GLdouble model[16], const GLdouble proj[16],
const GLint viewport[4],
GLdouble * winx, GLdouble * winy, GLdouble * winz)
{
GLdouble in[4], out[4];
in[0] = objx;
in[1] = objy;
in[2] = objz;
in[3] = 1.0;
transformPoint(out, model, in);
transformPoint(in, proj, out);
if (in[3] == 0.0)
return GL_FALSE;
in[0] /= in[3];
in[1] /= in[3];
in[2] /= in[3];
*winx = viewport[0] + (1 + in[0]) * viewport[2] / 2;
*winy = viewport[1] + (1 + in[1]) * viewport[3] / 2;
*winz = (1 + in[2]) / 2;
return GL_TRUE;
}
最后是transformPoint:
inline void GLBox::transformPoint(GLdouble out[4], const GLdouble m[16], const GLdouble in[4])
{
#define M(row,col) m[col*4+row]
out[0] =
M(0, 0) * in[0] + M(0, 1) * in[1] + M(0, 2) * in[2] + M(0, 3) * in[3];
out[1] =
M(1, 0) * in[0] + M(1, 1) * in[1] + M(1, 2) * in[2] + M(1, 3) * in[3];
out[2] =
M(2, 0) * in[0] + M(2, 1) * in[1] + M(2, 2) * in[2] + M(2, 3) * in[3];
out[3] =
M(3, 0) * in[0] + M(3, 1) * in[1] + M(3, 2) * in[2] + M(3, 3) * in[3];
#undef M
}
答案 2 :(得分:0)
对画家稍加旋转似乎可以增加文本的平滑度,但是质量有些中等:
clf.predict(np.array(30,4000,1))
答案 3 :(得分:0)
我在混合QPainter
和QOpenGLWidet
时遇到了一些麻烦,特别是使用QOpenGLWidget
作为绘画设备来渲染单个文本元素时。结果,我得到了清晰色彩的全屏显示。我以前的所有代码似乎都坏了。
因此,我想出了另一种使用QGraphicsScene
作为绘画设备的解决方案。随后,我将绘画者渲染到QImage
中,可以用来创建普通的2D-{QOpenGLTexture
。可以照常通过QOpenGLBuffer
缓冲区绘制此纹理。
void MyQOpenGLWidget::createTexture(int x, int y, int z, const QString& str, const QFont& font) {
// create an image of the text with transparent backround
QGraphicsScene scene;
scene.addText(str, font);
QImage img(scene.width(), scene.height(), QImage::Format_ARGB32_Premultiplied);
img.fill(QColor(0, 0, 0, 0));
QPainter painter(&img);
painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
scene.render(&painter);
// store the tex as member somewhere in the QOpenGLWidget
QOpenGLTexture tex(img);
// store the bufferindex as member somewhere in the QOpenGLWidget
int bufferIndex = 0
/*this is the index corresponding to first element of coords writen into buffer
-> the number of elements within your tex container times SPRITE_BUFFER_SIZE seems to be reasonable*/
// calculate coordinates
GLfloat coords[SPRITE_BUFFER_SIZE];
/* [SPRITE_BUFFER_SIZE=20=4*5]->4 corner points
3-dimensions +2 binary (determine corner point)*/
// write to buffer
buffer.bind()
buffer.write(sizeof(GLfloat)*bufferIndex, coords, SPRITE_BUFFER_SIZE * sizeof(GLfloat))
}
然后在paintGL
中绘制所创建的纹理
void MyQOpenGLWidget::paintGL() {
// somewhere within this function
tex.bind();
glDrawArrays(GL_TRIANGLE_FAN, bufferIndex / 5, 4);
}
确保使用正确的混合功能。
void MyQOpenGLWidget::initializeGL()
{
initializeOpenGLFunctions();
// somewhere within initializeGL
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
}