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Launching Viz {#tutorial_launching_viz}
=============
@next_tutorial{tutorial_widget_pose}
Goal
----
In this tutorial you will learn how to
- Open a visualization window.
- Access a window by its name.
- Start event loop.
- Start event loop for a given amount of time.
Code
----
You can download the code from [here ](https://github.com/opencv/opencv_contrib/tree/master/modules/viz/samples/launching_viz.cpp).
@include viz/samples/launching_viz.cpp
Explanation
-----------
Here is the general structure of the program:
- Create a window.
@code{.cpp}
/// Create a window
viz::Viz3d myWindow("Viz Demo");
@endcode
- Start event loop. This event loop will run until user terminates it by pressing **e**, **E**,
**q**, **Q**.
@code{.cpp}
/// Start event loop
myWindow.spin();
@endcode
- Access same window via its name. Since windows are implicitly shared, **sameWindow** is exactly
the same with **myWindow**. If the name does not exist, a new window is created.
@code{.cpp}
/// Access window via its name
viz::Viz3d sameWindow = viz::getWindowByName("Viz Demo");
@endcode
- Start a controlled event loop. Once it starts, **wasStopped** is set to false. Inside the while
loop, in each iteration, **spinOnce** is called to prevent event loop from completely stopping.
Inside the while loop, user can execute other statements including those which interact with the
window.
@code{.cpp}
/// Event loop is over when pressed q, Q, e, E
/// Start event loop once for 1 millisecond
sameWindow.spinOnce(1, true);
while(!sameWindow.wasStopped())
{
/// Interact with window
/// Event loop for 1 millisecond
sameWindow.spinOnce(1, true);
}
@endcode
Results
-------
Here is the result of the program.
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