GlutWindow::screenshot() doesn't work

[jslee02]

No description provided.

[olzhas]

it works for me, and I have some what related question,

is it possible to change in /dart/gui/Win3D.cpp

  if (mCapture)
    screenshot();

to

  if (mCapture)
    std::async(std::launch::async, screenshot);

[mxgrey]

Is there a particular motivation for launching it in a thread? I'd be concerned about race conditions causing problems, such as missing the frame that the user wanted, or worse: capturing a frame which is only partially rendered.

[jslee02]

Out of curiosity, which platform are you using? I've never seen this function working on ubuntu.

[olzhas]

I am using ubuntu as well, I did not check whether it is working on my computer, just saw it while reading more about C++11.

[jslee02]

I meant GlutWindow::screenshot() function. I had observed that GlutWindow::screenshot() function doesn't work on my ubuntu (maybe other platforms as well). The console says wrote screenshot frames/CaptureXXXX.png, but the files are actually not created at all. So I wondered if it really worked for you.

[olzhas]

I guess it works on my computer. When I press 'c', frames/CaptureXXXX.png are getting generated. and I can see those files there. however I don't remember if I created frames/ directory or the library did.

[jslee02]

I manually created frames directory, and not it works! It seems lodepng doesn't create necessary directories for the passed-in filename. GlutWindow::screenshot() should be changed to create frames directory when it doesn't exist. Thanks!

Also, I have a similar concern about the race conditions as @mxgrey mentioned. The screen data will be shared by the renderer and the screen-capturing threads.

[olzhas]

which fix will be better

//...
#include <boost/filesystem.hpp>

//...
void Win3D::keyboard(unsigned char _key, int /*_x*/, int /*_y*/) {
  char directory[8] = "frames";
//...
case 'c':
case 'C':
//...
  if (!boost::filesystem::exists(directory)) {
    boost::filesystem::create_directory(directory);
  }

  if (!boost::filesystem::is_directory(directory)) {
    std::cout << "frames/ is not a directory, cannot write a screenshot\n";
  }

or something without boost::filesystem

[jslee02]

I created a pull request for this (#623), which is similar to your suggestion but not using boost::filesystem as we're trying to minimize the dependencies as much as possible.