通过在Android（和iOS）上使用Qt用openGL绘制具有3d效果的2d线

Question

In my app, there are 10k ~ 200k lines on my screen. And the line is drawn in 2d space with 3d effect.

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

I try a pretty simple code: https://github.com/mkdh/Qt_QOpenGLWidget_screen_test.git

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?

The Application Output on creator:

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

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

Answer 1

I suggest you to use NanoVG instead of pure OpenGL which is very complicated. Your codes on OpenGL are tied to specific version of OpenGL and it can cause many portability issues. NanoVG is canvas drawing API backed on OpenGL(2,es,es2,es3) and have similar canvas API like HTML5. Also there is a Qt integration with NanoVG which is QNanoPainter.

Also its supported on linux, windows and android as well.

Answer 2

I can fix this problem by comment the code below.

// format.setVersion(3, 2);

// format.setProfile(QSurfaceFormat::CoreProfile)