Reacting to Player Input - Learning C# by Programming Games - page 88

if (currentKeyboardState.IsKeyDown(Keys.R)
&& previousKeyboardState.IsKeyUp(Keys.R))
currentColor = colorRed;

If the player did press the 'R' key, we assign the red colored ball sprite to the
currentColor variable. We follow the same procedure for the 'G' and 'B' keys, which
gives us the following if -instruction:

if (currentKeyboardState.IsKeyDown(Keys.R)
&& previousKeyboardState.IsKeyUp(Keys.R))
currentColor = colorRed;
else if (currentKeyboardState.IsKeyDown(Keys.G)
&& previousKeyboardState.IsKeyUp(Keys.G))
currentColor = colorGreen;
else if (currentKeyboardState.IsKeyDown(Keys.B)
&& previousKeyboardState.IsKeyUp(Keys.B))
currentColor = colorBlue;

Finally, we only need to add an additional drawing call to the Draw method so that
the current colored ball is drawn on top of the cannon:

spriteBatch.Draw(currentColor, barrelPosition, null , Color.White, 0f,
colorOrigin, 1.0f, SpriteEffects.None, 0);

Try to run the Painter2 program now, and see how the program responds to moving
the mouse and pressing the 'R', 'G' or 'B' keys.

6.6 What You Have Learned

In this chapter, you have learned:

• what an enumerated type is;

• how to react to mouse clicks and button presses using the if -instruction;

• how to formulate conditions for these instructions using boolean values;

• how to use if -instructions with different alternatives;

• how to deal with keyboard and gamepad input.