DOWN = 2
LEFT = 3
MAX_LENGTH = 256
SPEED = 2
OBJ
lcd : "LameLCD"Instructions
Need for speed
As it would happen, there isn’t much to do to make this happen. First, we create a constant, just to make our lives easier.
Snake.spin
Now we need to replace every instance of ++ and -- with += SPEED and -= SPEED.
Example 1. New Operators:
+=, -=, …These are shorter ways of writing certain operations that make your code easier to read.
x += y ===> x := x + y x -= y ===> x := x - y x *= y ===> x := x * y x /= y ===> x := x / y
Here’s what your movement code should look like now.
Snake.spin
if ctrl.Right
snakedir := RIGHT
if snakedir == LEFT and snakex[0] > 0
snakex[0] -= SPEED
if snakedir == RIGHT and snakex[0] < constant(128-2)
snakex[0] += SPEED
if snakedir == UP and snakey[0] > 0
snakey[0] -= SPEED
if snakedir == DOWN and snakey[0] < constant(64-2)
snakey[0] += SPEED
gfx.Sprite(@dot_gfx, snakex[0], snakey[0], 0)Ahh! Now it goes way, way fast at the beginning! I can hardly even see it. We can fix that, though.
Wait for me!
We can make the game more playable by setting the frame rate. That’s when we intentionally limit the speed of the game so that it runs at a more consistent speed instead of as fast as it feels like at the moment (a nice thing to have!).
LameLCD has a command just for this: lcd.SetFrameLimit. It comes in three speeds.
-
FULLSPEED(~35 frames/second): Like you’re watching TV! -
HALFSPEED(~18 frames/second): Starting to look choppy. -
QUARTERSPEED(~9fps frames/second): Pretty freaking slow.
You can try different values to see how they look; which one you use really depends on your game.
I’m going to go with HALFSPEED. You can call it whenever you like to change the frame rate, but I like to set it once at the beginning to keep it simple.
Snake.spin
PUB Main
lcd.Start(gfx.Start)
lcd.SetFrameLimit (lcd#HALFSPEED)
ctrl.Start