Game States - Learning C# by Programming Games - page 240

in our example consists of a single image that we have to load and display. We create
a SpriteGameObject instance for that, which we store in a member variable title and
we add it to the game world:
title = new SpriteGameObject("spr_title", 100);
this .Add(title);
We choose a high value for the layer (100) so that we can be sure that the title is
drawn on top of everything. But we have to do a little extra work to properly handle
input and update the game world, since we want the game to start only once the
title screen is no longer visible. We can do that by adding a few instructions to the
HandleInput method to distinguish between two states: the state in which we show
the title screen and the state in which we are playing the game:
if (title.Visible)
{
if (inputHelper.KeyPressed(Keys.Space))
title.Visible = false ;
}
else
base .HandleInput(inputHelper);
Looking at the if instruction, you can see that if the title screen is visible, we only
react when the player presses space. In that case, we set the title screens visibility
flag to false so that it is not drawn anymore. If the title screen is not visible, we call
the HandleInput method on all the game objects in the game world, in other words,
the game will react to the player as it should.
We follow very much the same procedure for the Update method, where we only
update the game world if the title is not visible:
if (!title.Visible)
base .Update(gameTime);
When we start the game, the player now gets to see a title screen before the game
starts. We are not done yet. In the next section, we are going to add a simple button
GUI element for showing a help frame.
17.3 Adding a Button for Showing the Help Frame
In this section, we will explain how you can add a simple button to a game, which
we will use to display a help frame. In order to do that, we are going to add another
class, Button , to our program. We will inherit from the SpriteGameObject class, and
add some simple behavior for checking if the player pressed a button or not. In the
Button class, we declare a boolean member variable that indicates whether the button