Problem with frame.fingers().count() interactions

[albertitu]

Hi everybody,

I have an issue when I use the frame.fingers().count() in my application. If i want to write something in the console like this

[ if (frame.fingers().count() == 5)
{
std::cout<<"...."
}] with this simple code I don't have any problem.

The problem comes when i want to interact with an OGRE applicattion like this

[if (frame.fingers().count() == 5)
{
if( mParent->planeNode->getPosition()[0]!=1000)
{
mParent->planeNode->setVisible(false);
mParent->planeNode->setPosition(Ogre::Vector3(1000,0,0));
}
if(mParent->scaleValueVp_==100)
{
mParent->scaleValueVp_=-0.5;
mParent->miniScreen_->setCorners(-1.0f,1.0f,mParent->scaleValueVp_,-mParent->scaleValueVp_);
}
else
{
mParent->scaleValueVp_=100;
mParent->miniScreen_->setCorners(-1.0f,1.0f,-1.0f,1.0f);
}
}}]

if Leap detects 5 fingers the application crashes. I've read the API reference documentation but I haven't been able to solve the problem.

someone knows how i can to proceed?

Thanks in advance,
Alberto

[Joe_Ward]

Hi Alberto,

In the version 2 SDK, the frame finger list will always have a multiple of 5 fingers. So if one hand is visible, your condition will always be true.

However that may be, it doesn't look like you are accessing any Leap Motion API functions inside this conditional. Have you tried setting a breakpoint and stepping through the code? If the code is otherwise good, a possibility is thread issues. If you are using listener, be aware that your onFrame callback is dispatched on its own thread. Perhaps the OGRE objects you are accessing can only be written to from a particular thread -- or require you to obtain a lock before writing to them.

[albertitu]

Hi Joe_Ward

First of all thank you for your fast answer, I have the problem with all fingers. I think that i need a lock before writting, because in the code that is below, Leap motion recognise my finger/s and it works fine but in this case i need to interact with the keyboard. I have to press any key from keyboard at the same time that Leap detects my fingers to get the action.

Do you think that I need a lock before or maybe is a thread problem? If i need a lock, how i can do it?

[
bool AppManager::OISListener::keyPressed( const OIS::KeyEvent &arg)
{

Leap::Controller controller;
Leap::Frame frame = controller.frame();
setObjectName(QString::number(frame.id()));
const Hand hand = frame.hands()[0];
const FingerList fingers = hand.fingers();

if(frame.fingers().count() == ' any_num' )
{
if( mParent->planeNode->getPosition()[0]!=1000)
{
mParent->planeNode->setVisible(false);
mParent->planeNode->setPosition(Ogre::Vector3(1000,0,0));
}
if(mParent->scaleValueVp_==100)
{
mParent->scaleValueVp_=-0.5;
mParent->miniScreen_->setCorners(-1.0f,1.0f,mParent->scaleValueVp_,-mParent->scaleValueVp_);
}
else
{
mParent->scaleValueVp_=100;
mParent->miniScreen_->setCorners(-1.0f,1.0f,-1.0f,1.0f);
}
}
return true;
}]

Alberto

[Joe_Ward]

A lock is often the solution to a thread problem, however, since you are using a framework (rather than writing all your own code) you have to be very careful here since you could cause other parts of the framework code to fail. If OGRE doesn't have a defined way of getting a lock so that you can safely write to these objects -- or some other way to synchronize threads, then you should look for another solution.

I noticed that OGRE provides its own FrameListener function that is called before a frame is rendered. This sounds like it could be a good place to run your Leap Motion code -- just getting the Leap::Frame object directly from the controller as you do in your keyPressed() callback above.

I only briefly looked through the OGRE docs, so there might be a better place to put this code, but I'm confident there is something similar that lets you update your world/scene between frames.

[albertitu]

Thank you Joe_Ward, I will be greateful if you could help me with the lock. In the synchronization of the threads, do i have to put the classes in common?

[Joe_Ward]

See mutex::lock for one way to synchronize threads -- but really, I don't think this is your best solution. If you use the OGRE FrameListener callback to access the Leap Motion frames, you don't have to worry about locking.

[albertitu]

I will try to solve first form the OGRE FrameListener callback. I let you know when i finish. Many thanks
Alberto

[albertitu]

Hi Joe_Ward
I've used the OGRE FrameListener callback (frameStarted, frameRenderingQueued and frameEnded) but i have the same problem. I will continue to looking for a solution in othre way.
If you know other possible way to solve it let me know please.

Thank you
Alberto

[Joe_Ward]

Are you saying that the code you posted above works in a FrameListener function if you remove the Leap Motion API class, but throws an exception if you make any calls to Leap Motion APIs?

[albertitu]

Hi joe,
Sorry for the delay. I say that i can't call the Leap Motion API with any Ogre FrameListener callback.
The second code that i've put above, it is working fine with the OIS objects (keypresed, keyreleased, mousereleased...). But i need that leap motion interacts with my app directly without intermediaries but when i do it this the app crashes.
I don't know what is the solution for this problem. Do you think that i have to put a lock?

Many thanks

Alberto

[Joe_Ward]

I'm not sure that is the problem anymore. If you just run:

Leap::Controller controller;
Leap::Frame frame = controller.frame();

In your FrameListener callback (or any OGRE callback), you are running in the thread provided by OGRE, not one started by the Leap Motion library. There shouldn't be any threading conflicts in this case.

[albertitu]

Sorry for the last explanation i think that i've explained wrong. The problem is that if i use any OGRE FrameListener callback i don't have access to an object (mParent) that i need for the app. The Ogre FrameListener callback works fine with Leap.

I don't know how to reference this object inside of the class OgreFrameListener. Do you have any idea?

[albertitu]

Hi Joe,

This time is a different issue that the last.
I've installed the 64 bits version of leap in a new PC, and i have problems with frame.fingers().count(), it only detects 5 fingers. If I put 0,1,2,3,4 fingers only detects 5 fingers, and if I put two hands only detects 10 fingers indepently how many fingers put. Do you know what is happened?

Thanks in advance

Alberto

[Joe_Ward]

In an older version of the SDK, we only reported the fingers that were unambiguously detected by the Leap sensor. Since version 2, though, we use an internal skeletal model of the hand and we deduce the positions of fingers which aren't clearly visible. This means that whenever a hand is detected, all of its five fingers are included in the fingers array. To get the number of fingers that are more or less straight, use fingers().extended().count().

[kayumiy]

fingers = frame.Fingers.Count;

not working