draw 2d line with 3d effect with openGL by using Qt on Android (and iOS)
<p>In my app, there are 10k ~ 200k lines on my screen. And the line is drawn in 2d space with 3d effect. </p>

<p>I want to speed my drawing's speed on iOS and Android by using Qt. 
Hence, I want to try openGL on Qt.</p>

<p>I try a pretty simple code:
<a href="https://github.com/mkdh/Qt_QOpenGLWidget_screen_test.git" rel="nofollow noreferrer">https://github.com/mkdh/Qt_QOpenGLWidget_screen_test.git</a></p>

<p>It should show green screen on my Android but it shows white screen on my Android.
Do you know why it shows white screen on my Android? And what should I do if I want to use openGL on this Android?</p>

<p>The Application Output on creator:</p>

<pre><code>InputMethodManagerService( 536): Enabling: SessionState{uid 10287 pid 25474 method 224d6020 session 2250c900 channel ClientState{22861db8 uid 10287 pid 25474} (server)}
W/My First openGL Widget(25474): (null):0 ((null)): Cannot find EGLConfig, returning null config
W/My First openGL Widget(25474): (null):0 ((null)): QEGLPlatformContext: Failed to create context: 3005
W/My First openGL Widget(25474): (null):0 ((null)): Cannot find EGLConfig, returning null config
W/My First openGL Widget(25474): (null):0 ((null)): QEGLPlatformContext: Failed to create context: 3005
W/My First openGL Widget(25474): (null):0 ((null)): QOpenGLWidget: Failed to create context
W/My First openGL Widget(25474): (null):0 ((null)): Cannot find EGLConfig, returning null config
W/My First openGL Widget(25474): (null):0 ((null)): QEGLPlatformContext: Failed to create context: 3005
W/My First openGL Widget(25474): (null):0 ((null)): QOpenGLWidget: Failed to create context
W/My First openGL Widget(25474): (null):0 ((null)): Cannot find EGLConfig, returning null config
W/My First openGL Widget(25474): (null):0 ((null)): QEGLPlatformContext: Failed to create context: 3005
W/My First openGL Widget(25474): (null):0 ((null)): QOpenGLWidget: Failed to create context
W/My First openGL Widget(25474): (null):0 ((null)): composeAndFlush: makeCurrent() failed
W/My First openGL Widget(25474): (null):0 ((null)): composeAndFlush: makeCurrent() failed
</code></pre>

<p>By the way, why can't I draw line with glBegin(GL_LINES) as the comment in void MyGLWidget::initializeGL()?</p>