Android provides a class called GLSurfaceView, which is a widget that is drawn by OpenGL. The drawing logic is encapsulated via an interface called GLSurfaceView.Renderer, which we will implement in ARCubeRenderer. The interface requires the following methods:
onDrawFrame(GL10 gl): This is called to draw the current frame. Here, we will also configure the OpenGL perspective and viewport (its drawing area on the screen) because the interfaces ofARCubeRendererandCameraProjectionAdapterpotentially allow the perspective to change on a frame-to-frame basis.onSurfaceChanged(GL10 gl, int width, int height): This is called when the surface size changes. For our purposes, this method just needs to store the width and height in member variables.onSurfaceCreated(GL10 gl, EGLConfig config): This is called when the surface is created or recreated. Typically, this method configures any OpenGL settings that we will not subsequently change. In other words, these...