Nuts and Volts - May 2014

is to move the paddle along the bottom of the screen in order to deflect a ball into a set of bricks at the top of the screen. If all of the bricks are eliminated before your five plays have been expended, then you win the game.

Another action game is Aliens in which you use your ground-based phasers to blast the alien ships out of the sky. Watch out, because they shoot back. You must destroy all of the alien ships before they destroy all of the buildings in the city.

When writing games for the Seeed Studio Touch Shield involving movement, you should remember that only the opaque portion of each character is drawn on the screen by the drawString function. Any background color behind the transparent portion of a character is not overwritten. To erase a character, simply draw it in the background color.

For example, when moving the ball in the Bricks game, the previous position of the ball is drawn in the background color. The new position of the ball is then drawn in the specified foreground color. To the player, this will give the appearance of a moving ball.

For an object that is going to be moved, you can also use the fillScreen function to fill the object’s area using the background color, then draw the object in its new location in the specified foreground color. Either way, you will accomplish the same purpose.

For arcade-style games, you may want to use the touchPosition function because you can read the position of a finger (or stylus) press very rapidly and respond accordingly.

To discover additional functions not described here, do the following: Start the Arduino IDE. Click the File option. Mouse over the Examples option. Mouse over the TFTscreen library folder. Open each of the files in the TFTscreen folder and examine the code.

You will discover the following functions: Tft.drawChar, Tft.drawCircle, Tft.drawFloat, Tft.drawHorizontalLine, Tft.drawNumber, Tft.drawVerticalLine, Tft.fillCircle, and Tft.fillRectangle. Be sure to run the example code on your system to see how each of the functions work.

In game programming, you should always try to consider every possible scenario and design your system accordingly. Programmers should pay heed to Spencer’s Rule of Engineering Design: Leave nothing to chance because chance is a lousy engineer.

I hope you have lots of fun writing games for the Arduino. NV

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