我在渲染 OpenGL 场景时遇到问题。
背景是我想在预览窗口中显示来自视频捕获设备的帧。我正在使用 OpenCV 和 Qt。为了测试我正在从我的 MacBook 网络摄像头捕获。预览窗口为 200x200,捕获的帧为 640x480。我不担心保持纵横比。
来自 IplImage 结构的其他信息:
- Debug: channels: 3
- Debug: depth: 8
- Debug: dataOrder: 0
- Debug: align: 4. Alignment of image rows 4 or 8
- Debug: origin: 0. 0=top left, 1=bottom left
- Debug: widthStep: 2560.
- Debug: colorModel: RGB
所以这张图片显示了当前的状态。
Current capture http://clinsoftsolutions.com/fgvc4.png
我开始使用 glDrawPixels,但效果不佳。我得到了输出,但没有缩放。
目前我正在尝试使用纹理,这是我用于 GL 交互的代码
void VideoCaptureWidget::initializeGL()
{
qDebug("initializeGL called");
qglClearColor(QColor::fromRgb(0,0,0)); // set clear colur to black
glDisable(GL_DEPTH_TEST);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, this->width(), this->height(), 0.0f, 0.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glGenTextures(3, &m_texture);
glBindTexture(GL_TEXTURE_2D, m_texture);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
glBindTexture(GL_TEXTURE_2D,m_texture);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,this->width(),this->height(),0,GL_BGR,GL_UNSIGNED_BYTE,NULL);
glDisable(GL_TEXTURE_2D);
}
void VideoCaptureWidget::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDisable(GL_DEPTH_TEST);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f,this->width(),this->height(),0.0f,0.0f,1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D,m_texture);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,m_image->width,m_image->height,0,GL_BGR_EXT,GL_UNSIGNED_BYTE,m_image->imageData);
glBegin(GL_QUADS);
glTexCoord2i(0,1); glVertex2i(0,this->height());
glTexCoord2i(0,0); glVertex2i(0,0);
glTexCoord2i(1,0); glVertex2i(this->width(),0);
glTexCoord2i(1,1); glVertex2i(this->width(),this->height());
glEnd();
glFlush();
}
void VideoCaptureWidget::resizeGL(int width,int height)
{
qDebug("reszieGL called");
glViewport(0,0,this->width(),this->height());
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f,this->width(),this->height(),0.0f,0.0f,1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
图像是在定时器槽中捕获的,m_image 是一个_IplImage 指针
void VideoCaptureWidget::_captureFrame() {
m_image = cvQueryFrame(m_capture);
if(!m_image) {
qDebug("VideoCaptureWidget::_captureFrame(): Error capturing a frame...");
}
//Draw the scene
glDraw();
}
我真的希望有人以前见过这种扭曲的图像并知道问题出在哪里。
最佳答案
另一种方法是将 BGR 帧转换为 RGBA,然后使用 glTexImage2D()
将它们上传到 GPU。我在my repository上传了一个完整的demo , 检查 cvQTcameraGL .
相关代码如下:
// Note: trying to retrieve more frames than the camera can give you
// will make the output video blink a lot.
cv_capture >> cv_frame;
if (cv_frame.empty())
{
std::cout << "GLWidget::paintGL: !!! Failed to retrieve frame" << std::endl;
return;
}
cv::cvtColor(cv_frame, cv_frame, CV_BGR2RGBA);
glEnable(GL_TEXTURE_RECTANGLE_ARB);
// Typical texture generation using data from the bitmap
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, _texture);
// Transfer image data to the GPU
glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0,
GL_RGBA, cv_frame.cols, cv_frame.rows, 0,
GL_RGBA, GL_UNSIGNED_BYTE, cv_frame.data);
if (glGetError() != GL_NO_ERROR)
{
std::cout << "GLWidget::paintGL: !!! Failed glTexImage2D" << std::endl;
}
关于qt - 将 OpenCV IplImage 渲染到 QGLWidget,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15705627/