At school we have a policy of non violence, but one of the things that makes games lots of fun is the skill of shooting at things.  So to help us remember that it is just a game and avoid any 'violence', you are asked not to use images or sprites that look like guns or people.  Keep your shooting to things like hamburgers at teddy bears! 

In this exercise we are going to have a monster that shoots an icy-pole bullet.

Create a new game with a bullet and monster sprite and a bullet and monster object.

Place the monster object in a room.

 

Open the properties window for the Monster object.

Add a keypress event for when the space bar is pressed. Take care not to use a Keyboard Event!Choose the Main1 tab, and choose the 'Create an Instance of an Object'

Select the following options:

We are creating a bullet at the same x coordinate as the monster, but 2 pixels above the monster.  Ticking relative means the coordinates are added to the coordinates of the monster.  (This will make more sense later)

 

Now we need to make the bullet move.

Open the properties window for the objBullet.

Add a create event.

From the movement tab, choose Set the Vertical Speed

Set the speed to be -6  (Making the vertical speed -6 means the bullet will move upwards)
 
 There is one more thing we need to do.  After the bullet disappears from the play area, even though we can't see it, it is still in the game moving upwards forever.  The computer keeps track of all the bullets, so if we don't destroy them after they leave the play area, our game will get slower and slower as the computer tries to keep track of all the bullets.

We can fix this by adding an event to destroy the bullet after it leaves the play area.

Open the properties for objBullet.

Add an 'Other' Event > Choose Outside Room

From the Main1 tab, choose Destroy the Instance

  Now try your game.  Press spacebar to shoot.

There is still a long way to go before our game is much good to play, but we are on the way!

Activity 1

Make a bullet move across the screen until it is outside the play area then destroy it.

Hint:  You will need to set the horizontal speed, not the vertical speed, for the bullet.

Save it as moveacross

Activity 2

Try setting both the horizontal and vertical speeds.  What do you think will happen?

Activity 3

Make the bullet shoot in 8 different directions, depending on which key is pressed.  For example, pressing the A key will shoot left, S key will shoot left and upwards, D key will shoot straight upwards etc.

Activity 4

How could you make it shoot in even more directions?

 

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Making an explosion from a bullet

When a bullet hits something you may want to make an explosion.  This is how you do it.

Make a new game. Add bullet and animated explosion sprites and objects to your game

Place the bullet at the bottom of the room and make it move up the screen by giving it a vertical speed of -8:
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We want the bullet to explode when it is 50 pixels from the top of the screen. Every Step test whether y<50 (ie the bullet is within 50 pixels of the top of the screen). If it is, then create an explosion and destroy the bullet.

Instead of making the bullet explode when it is near the top of the screen, you could use a collision event for an explosion when the bullet hits something.

instructions

To make the explosion disappear, use the animation end event for the Explosion.

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Save your game sample as explosion

 

Blocks of Code

You will notice in the code above the actions for starting and ending a block of code

This means that if the question at the top is true, the entire block of code (all the actions) will be executed, otherwise if the question is false, none of it will be executed.

Activity 5

Make an object move across the screen in the top half of the play area.

Have another object at the bottom of the screen (say a plane).  When the spacebar is pressed the plane should shoot at the moving object.  If it hits it, then the plane and bullet should explode and points should be scored.  If the bullet misses, it should be destroyed when it leaves the play area.

Extension: Add events to move the plane sideways when the left and right keys are pressed.

Save it as shooting

 

 

Changing Direction of Sprites

Sometimes you have a sprite that is facing in a particular direction, for example this plane appears to be flying upwards:

When you change directions to fly left, it does not look right, so you need a sprite that looks like this:

To do this you must first create the sprites to face in each of the directions.  This video will show you how:

When using multiple sprites for the same object you should turn off Precise Collision Checking and the Bounding box should be set to manual.  The bounding box should be identical for all sprites.   The bounding box does not have to surround all pixels of the sprite, it is just the area that is checked for collisions.

Otherwise when the sprite is changed, the object may become stuck.

Once you have created the sprites, you need to set up events to change the sprite for the object whenever the left, right, up or down keys are pressed.  This video will show you how:

Often you want to stop your object to stop  moving when you are no longer pressing a key and you would like the object to change to a 'stopped' sprite.  This video will show you how:

Add a stopped sprite into the activity above.

Shooting in the Direction You are Facing

It can be quite challenging to make your character shoot in the direction it is facing.

Here is an example you can download that will show you how it is done.  Read the game information to see how to set it up.