Taking the Development Ahead - Learn OpenGL ES: For Mobile Game and Graphics Development - page 228

▪ The code inside the onDrawFrame() method is refactored and
is extracted to two separate methods:
▪ void updateModel(int up-
DownValue, float zAngle)
▪ void renderModel(GL10 gl)
▪ The updateModel() method contains the lines of code from
Listing 6-7 . From this point onwards, the updateModel()
method will contain the code that updates the matrices which in
turn update the position of objects.
▪ The renderModel() method, as the name suggests, contains
the code that renders graphics. This comprises the calls to meth-
ods, such as glUseProgram , glUniform* , glVertexAt-
tribPointer , glEnableVertexAttribArray ,
glDraw* .
▪ To ensure that rendering of every frame takes the same amount of
time, we need to calculate the time taken by the current frame and
then sleep it accordingly. Because of the way garbage collection
takes place in Java, the time taken for rendering of each frame is
not guaranteed to be the same. By calling Thread.sleep()
method (as shown in Listing 6-8 ) in the Renderer thread, we can
adjust this time. Also note that before the rendering begins, it is
always good to call the garbage collector explicitly so that it can
free up the memory occupied by objects that are no longer in use.
Note Although it is all right to block the Renderer thread, for in-
stance by calling the Thread.sleep() method, the UI thread
should never be blocked.
Listing 6-8. TANK FENCE GAME 2/src/com/apress/android/tankfencegame2/
GLES20Renderer.java
public void onDrawFrame(GL10 gl) {
System.gc();