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| Listing 3 . Beginning of the updateAndRender method of the GameContainer class. |
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protected void updateAndRender(int delta)
throws SlickException {if (smoothDeltas) {
if (getFPS() != 0) {delta = 1000 / getFPS();
}//end if}//end ifinput.poll(width, height);Music.poll(delta);
if (!paused) {storedDelta += delta;if (storedDelta>= minimumLogicInterval) {
try {if (maximumLogicInterval != 0) {
long cycles =storedDelta / maximumLogicInterval;
for (int i=0;i<cycles;i++) {
game.update(this,(int)maximumLogicInterval);}//end for loopint remainder =
(int)(delta % maximumLogicInterval);if (remainder>minimumLogicInterval) {
game.update(this,(int)(delta % maximumLogicInterval));
storedDelta = 0;} else {
storedDelta = remainder;}//end else
} else {game.update(this, (int) storedDelta);
storedDelta = 0;}//end else} catch (Throwable e) {
Log.error(e);throw new SlickException(
"Game.update() failure - check the game code.");}//end catch
}//end if on minimumLogicInterval} else {
game.update(this, 0);}//end else |
Another verbal description
This is my verbal description of what happens when the gameLoop method calls the updateAndRender method.
(I will not discuss those actions that represent communication with the hardware via the Lightweight Java Game Library (lwjgl) as well as a fewother housekeeping actions) .
The updateAndRender method begins by selecting between normal delta and "smooth deltas."
(Smooth delta values essentially represent a moving average of individual delta values computed in asomewhat roundabout way.)
Calling the update and render methods
The update method of the Game object will be called none, one, ormore times during each iteration of the game loop on the basis of the contents of two variables named minimumLogicInterval and maximumLogicInterval .
The default value for minimumLogicInterval is 1. The default value for maximumLogicInterval is 0. Methods are provided by which you can change the values of these two variables.
The render method of the Game object will be called only once during each iteration of the game loop following the call or calls to the update method.
If the paused property is true, the update method is called once passing a value of zero for delta. Otherwise, the value ofdelta is added to the contents of a variable named storedDelta for the purpose of accumulating individual delta values.
Then the method enters a somewhat complex logic process, which I will describe as follows:
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