GameLogic.GameStateStack Class
This class allows you to manipulate some GameStates. It is quite useful and widely used in Game Programming The default usage of this GameStateStack is to be added to a Gameloop which will call periodically the GameStateStack's update and draw methods. The GameStateStack class act like the Window class. When you create a GameStateStack object you must give it a canvas. You can add and suppress GameState objects from the GameStateStack. The main difference with the Window class is that the GameStateStack organize Layers in differents GameStates. And the focused GameState can change be change at runtime.
Let's take an example, you want to do a little game which contains 2 states :
- Paused
- In Game
Each state have to contains its own layers which represent it. But it is not the purpose of this Class. Refer to GameState class for more informations about that.
You have to add the first State to the GameStateStack, in our case it is the "In Game" state. Then you can add the GameStateStack to the Gameloop. Then during updating process. Your "In Game" state will be updated. And during its update it can change the current state of the GameStateStack. For example, if the "In Game" state detect that you have pressed "space" to set the game in pause. Then a new State must be pushed to the GameStateStack which will be the "Paused" state.
Then, the pause state will be the focused state. if it detects that the "space" key is pressed again. Then the current state of the GameStateStack must be poped. Then, the current state will be again the "In Game" state, and it will be resume where the "pause" state have been created. That's why this class is called a Stack, because internally, the GameStates are stacked and saved. It allows you to manage and save differents states. Like in the previous example you can save the current state of the game and set it in pause.
Note that all the States are drawn on the canvas during draw procedure. Also note that only the last State which have been added to the GameState is updated. That's why all other states are paused. Because they are no more updated.
Constructor
GameLogic.GameStateStack
-
canvas
Parameters:
-
canvasHTMLCanvasElementthe canvas on which the States will be drawn.
Methods
draw
()
This method allows you to draw the GameStateStack, notice that all the GameState will be drawn. From the last GameState to the first.
goToState
-
name
This method try to find a State in the stack which has a specific name. It allows you to jump from a state to another.
Parameters:
-
nameStringthis parameter specify the name of the state to find in the stack.
Returns:
pop
()
This method allows you to destroy the current GameState. Notice that when you pop a GameState it will be destroyed and the previous state will be resume.
push
-
gameState
This method allows you to add a State to the GameStateStack. Notice that when you push a GameState other states will be paused, It means that only the State that you've add to the GameStatePattern will be updated.
Parameters:
-
gameStateGameStateThe gameState which will be the current GameState to be active.
update
-
elapsedTime
This method allows you to update the GameStateStack, notice that only the last GameState will be updated.
Parameters:
-
elapsedTimeObject