屏幕旋转时Android OpenGL重新加载程序

Question

It seems that in android with opengl when you rotate your screen, activity gets recreated. Does thus cause all the opengl programs to be unloaded from the memory? When I use GLES20.glUseProgram(savedProgramId); It says that there is no such program. What do I do wrong? (By the way, I keep my program id in a static field)

Answer 1

You can make changes to your manifest to indicate that you will handle changes in screen orientation yourself.

See 'configchanges'+'orientation' here: http://developer.android.com/guide/topics/manifest/activity-element.html

However, you'll still have the problem that your OpenGL context will be lost when the user switches between apps.

The most correct thing to do is to fully handle loss and recreation of the OpenGL context and all associated resources. In a large and complex project this can be very difficult.

A reasonable alternative is to use setPreserveEGLContextOnPause ( http://developer.android.com/reference/android/opengl/GLSurfaceView.html#setPreserveEGLContextOnPause%28boolean%29 ) which is available on Android 4.0 and above.

The documentation states that the OpenGL context might not always be preserved, but my opinion is that it works well enough to ship with and avoids a lot of complicated code. When your app is in the background, it might get terminated due to memory pressure anyway, so if it's terminated occasionally due to a device's limit on EGL contexts then that seems acceptable to me.