Establishing a Build Environment - Android NDK Game Development - page 25

Windows Native Application Our Portable Game

Initialization OnStart() Java Activity

Main loop

OnMouseMove()

Native Android Library

WinAPI
Window
Function

Pull system
messages

OnMouseDown()

SendMotion() JNI callback

DrawFrame() JNI callback

OnMouseUp()

Update game
state

Update game
state

OnTimer()

JNI calls

OnDrawFrame()

Render frame Render frame

Shutdown OnStop() ExitNative() JNI callback

The rest of the topic is centered on this kind of architecture and the game functionality will be
implemented inside these portable On...() callbacks.

There is yet another important note. Responding to timer events to create animation can be
done on Windows with the SetTimer() call and the WM_TIMER message handler. We get
to that in Chapter 2 , Porting Common Libraries, when we speak about rigid body physics
simulations. However, it is much better to organize a ixed time-step main loop, which is
explained later in the topic.

See also

F Chapter 6 , Unifying OpenGL ES 3 and OpenGL 3
F The recipe Implementing the main loop in Chapter 8 , Writing a Match-3 Game

Unifying the cross-platform code

Right now, we have two different versions of a simple program ( Win_Min2 and App3 ). Let us
see how to unify the common parts of the code.