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Setting the Premultiply Alpha property value to False in Figure 7 will cause the alpha value to be ignored. This will produce the output image shown in Figure 4 .
As explained earlier, honoring alpha transparency is the default case in XNA 4.0. Figure 4 was created by setting the Premultiply Alpha property (see Figure 7 ) of the image named gorightarrow.png to a value of False and then re-running the program. This causes even the pixels with the very low alpha values to be opaqueas shown in Figure 4 .
You can draw as many sprites as you need following the call to the Begin method in Listing 8 .
Each sprite drawn will be drawn according to the parameters passed to the Begin method.
If you need to draw some sprites with different parameters, call the SpriteBatch.End method and start the sequence over with a new call to the SpriteBatch.Begin method and new parameters.
In this case we only have one sprite to draw. Listing 8 calls the SpriteBatch.Draw method to draw that sprite and then calls the SpriteBatch.End method to end the drawing sequence.
There are several overloaded versions of the SpriteBatch.Draw method. According to the documentation , the version used in Listing 8
The code in Listing 8 passes three parameters to the Draw method:
According to the documentation , this method
When you instantiate an object from a class that extends another class and overrides a method from the superclass, the new object contains both theoriginal version and the overridden version of the method.
Often it is desirable or necessary to cause both versions to be executed. The code in Listing 9 shows the syntax used to cause an overridden method to call the original version of the method using the keyword base . The keyword base is a reference to that portion of the object that represents the properties, events, and methods of thesuperclass.
Listing 9 . Call Game.Draw on the superclass.
base.Draw(gameTime);
}//end Draw method}//End class
}//End namespace The statement shown in Listing 9 is already contained in the skeleton code produced by Visual C# (see Listing 3 ).
The documentation for the Game.Draw method contains the following:
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