Part 1 - Making the Bird Move #
Let’s make our bird respond to mouse input. Let’s add a new function. Functions can be in any order in the file, but a good place is just before the draw function.
- Add the following code just before the
drawfunction (remember to use the name of your bird):
def on_mouse_down():
print ('The mouse was clicked')
barry_the_bird.y -= 50
All Actors have x and y positions. Remember when we made Barry, we said barry_the_bird = Actor…, so that means he is an Actor!
x is the left/right position, and y is the up/down position. The last line of our new function is changing the y position of Barry.
- Press Play to test the game. Click in the window to make the bird move.
What happens if you replace 50 with a different number?
Can you figure out what the line that starts with print does? Hint : Look at the bottom of the Mu editor.
The on_mouse_down function is called every time you click the mouse. Calling a function means doing the instructions it contains. If we want to make the bird move smoothly we need to move him in small amounts, and do it so often that it looks smooth.
An update function is a function that gets called again and again very quickly. Normally 60 times in every second.
- Add this function to your file (remember to use the name of your bird):
def update():
barry_the_bird.y += 1
Can you guess what this will do?
- Press Play to find out
What happens if you change the 1 to a different number?
Can you make the bird start in a different place? Hint: Try changing the line where you created your bird as an Actor.
Let’s add a new variable which controls the speed of the bird. Think about it like a slider we can change. We can actually put one variable inside another. barry_the_bird already has x and y variables inside him. We can add another one like this:
- Add this line at the end of the file:
barry_the_bird.speed = 1
This is another variable that you are creating. So again you can call it whatever you want. You just need to use the same name again later when you want to use it. I chose to call it speed because it controls how fast the bird moves. Another good name would be flying_speed, but if you named it banana_squid it would still work.
- Now change the update function to use this variable, make sure to use the variable name you chose for the bird, and the name you chose for speed:
def update():
barry_the_bird.y += barry_the_bird.speed
When we use barry_the_bird.speed in this function, we will actually be using the number that speed is currently set to. So every time update is called (lots of times per second), the y position of the bird is changed by however much speed is set to. That means that the speed can change even while the game is running.
Your whole file should now look like this:
TITLE = 'Flappy Bird'
WIDTH = 400
HEIGHT = 708
def update():
barry_the_bird.y += barry_the_bird.speed
def draw():
screen.blit('background', (0, 0))
barry_the_bird.draw()
def on_mouse_down():
print ('The mouse was clicked')
barry_the_bird.y -= 50
barry_the_bird = Actor('bird1', (75, 350))
barry_the_bird.speed = 1
- Press play
Can you click fast enough to keep the bird on the screen?
How high can you set the speed before it’s too hard to keep on the screen?
Challenges #
Well done! You made it to the end of part one.
If you have still have time today, then have a go at these extra challenges:
Make the bird move left and right instead of up and down
Make it so that the bird stops moving if the player clicks anywhere. Hint : The code should change the value of speed when you click
Make is so that when you hold the mouse button down the bird stops moving, but when you let it go it moves again. Hint: You will need to add a new function called on_mouse_up
Add another bird who moves with a different speed
Make it so that when a bird goes off the edge of the screen, it comes back on the other side. Hint: ask a mentor how to add an
ifstatementMake it so that clicking the mouse makes the bird get faster each time