GLRenderer.RenderCallback

@WorkerThread
fun onDrawFrame(eglManager: EGLManager): Unit

Callback used to issue OpenGL drawing commands into the EGLSurface created in onSurfaceCreated. This EGLSurface is guaranteed to be current before this callback is invoked and EGLManager.swapAndFlushBuffers will be invoked afterwards. If additional scratch EGLSurfaces are used here it is up to the implementation of this method to ensure that the proper surfaces are made current and the appropriate swap buffers call is made

This method is invoked on the backing thread

@WorkerThread
open fun onSurfaceCreated(
    spec: EGLSpec,
    config: EGLConfig,
    surface: Surface,
    width: Int,
    height: Int
): EGLSurface?

Used to create a corresponding EGLSurface from the provided android.view.Surface instance. This enables consumers to configure the corresponding EGLSurface they wish to render into. The EGLSurface created here is guaranteed to be the current surface before onDrawFrame is called. That is, implementations of onDrawFrame do not need to call eglMakeCurrent on this EGLSurface.

This method is invoked on the GL thread.

The default implementation will create a window surface with EGL_WIDTH and EGL_HEIGHT set to width and height respectively. Implementations can override this method to provide additional EGLConfigAttributes for this surface (ex. EGL14.EGL_SINGLE_BUFFER.

Implementations can return null to indicate the default surface should be used. This is helpful in situations where content is to be rendered within a frame buffer object instead of to an EGLSurface