Scrolling Shooter 1945

Transcription

1 Scrolling Shooter 1945 Let us now look at the game we want to create. Before creating a game we need to write a design document. As the game 1945 that we are going to develop is rather complicated a full design document would typically consist of a couple of pages. To avoid making this tutorial too long we will just give a short description here. The game will look something like this: The player controls the big yellow plane that flies upwards. All four types of enemy planes are shown in the image above. At the bottom the score, number of lives left, and the damage (in the form of the green bar) are shown design document Description In this game you control a plane flying over a sea. You encounter an increasing number of enemy planes that try to destroy you. You should avoid these or shoot them. The goal is to stay alive as long as you can and to destroy as many enemy planes as you can. Game objects The background is formed by a scrolling sea with some islands. The player s plane flies over this sea. You can shoot bullets that destroy enemy planes. There are four types of enemy planes: a plane that you encounter and should be destroyed, a plane that fires bullets downwards, a plane that fires bullets towards the player s plane, and a fast enemy plane that comes from behind rather than from the front. Sounds There are some explosion sounds and there is some background music. 1

2 Controls The player controls the game with the arrow keys. With the space key you fire a bullet. Only one bullet can be fired every five steps. Game flow The player immediately jumps into the game. The player has three lives. When all lives are gone a high-score table is shown. Pressing the <F1> (help) key will give a brief explanation. Pressing the <Esc> key will end the game. Levels There is just one level, but more and more enemy planes will arrive: first only the easy type but later the more difficult types. 2

3 Illusion of Motion Creating Motion 1. Firstly add the water background to the game 2. Add background 2.1. Load background 2.2. Find the image called water and double click 3. Create a room called Rm_Main 4. Go to the background tab 5. add the background to the room by clicking on the list button 6. Add the value 2 in the vertical speed 7. Play the game and see if the background is moving as expected Adding Island 1. Add the three island sprites to the game 2. Create objects for all three sprites 3. Each island will have a create event and a step event 4. Add a create event 5. Insert vertical speed and set to 2 6. add a step event 7. Add a test variable 7.1. Variable: Y 7.2. Value: room_height 7.3. Operation: larger than 8. Add a jump to position 8.1. X: random(room_height) 8.2. Y: Repeat for Island 2 and Island To finish add these island to the stage. 3

4 Main Plane Now that the scrolling background is ready it is time to make the plane that the player will control. This is actually rather easy. First of all we need a sprite for the plane. When creating this sprite there is one important thing. We set the X and Y of the Origin to 32. This means that the origin of the sprite is the centre of the plane. So whenever we later set the plane at a position or test the position, we mean the position of the centre of the plane, not the top-left point, which is normally used as the origin. This is important to make sure that for example bullets come from the centre of the plane, not from the left side. Creating the Plane 1. Insert the plane sprite and call it spr_myplane 2. Make an object and call it obj_myplane 3. Set the depth of the plane to Add a keyboard event: Down 5. In the actions add a test variable 5.1. Variable: Y 5.2. Value: room_height Operation: smaller than 6. Next add a jump to position 6.1. X: Y: Relative is checked 7. Add a keyboard event: Left 8. In the actions add a test variable 8.1. Variable: X 8.2. Value: 40 4

5 8.3. Operation: larger than 9. Next add a jump to position 9.1. X: Y: Relative is checked 10. Add a keyboard event: Up 11. In the actions add a test variable Variable: Y Value: Operation: larger than 12. Next add a jump to position X: Y: Relative is checked 13. Add a keyboard event: Right 14. In the actions add a test variable Variable: X Value: room_width Operation: smaller than 15. Next add a jump to position X: Y: Relative is checked 16. Add the plane to your room 17. Your plane should now move around the room without going too far off the screen. Test your plane to make sure, once this has been done you can move on 5

6 to adding some enemies to avoid. Creating an Enemy 1. Insert an enemy sprite into the game and call it spr_enemy1 2. Also insert the explosion1 sprite and sound, this way we can add some effects to the game. 3. Create an object for explosion Add an other event called animation end 3.2. In actions destroy the instance 3.3. Select object: Obj_explosion1 4. Create an enemy object and call it obj_enemy1(check solid) 5. Firstly add a create event 5.1. Set the vertical speed to 4 6. Next add a step event 6.1. Add a test variable 6.2. Variable: Y 6.3. Value: room_height Operation: larger than 7. Add a jump to position 6

7 7.1. X: random(room_width) 7.2. Y: Next add a collision event with the object: MyPlane 8.1. In actions firstly play the sound: Explosion1 9. Then use a create instance 9.1. Object: obj_explosion Relative (this will place the explosion where the plane is) 10. Add a jump to position X: Random(room_width) Y: Add a set Health Value: Relative 12. Add enemy object to the room and test Creating a bullet 1. Insert a Bullet sprite (or make your own) 2. We create an object with this sprite. 3. We will give it the default depth 0 such that it will appear below the plane but above the islands. 4. In the create event we give it a vertical speed of 8 to make it move upwards. 5. Add a step event 6. Add a test variable 7

8 6.1. Variable: Y 6.2. Value: Operation: smaller than 7. Add a destroy the instance 7.1. Make sure that self is checked (self meaning the bullet sprite) 8. Lastly open obj_enemy1 and add a Collision event with the bullet you just created 9. Again add the play sound : Explosion Destroy the instance Other (in this case the bullet) 11. Then add a create instance Object: obj_explosion Relative (with will place the explosion where the plane is) 12. Add a jump to position X: random(room_width) Y: Add a set the score relative to Save 8

9 Shooting the bullet 1. Go to the obj_myplane 2. Add a create event 3. Add a set variable called can_shoot 3.1. Variable: can_shoot 3.2. Value: 1 4. Add a keyboard event using the space bar, this will shoot the bullet at any enemies 5. Firstly we want to test whether can_shoot is equal to 1 6. Next we will create an instance of the object: OBJ_Bullet 6.1. X = Y= Relative is checked 7. Then set the Variable can_shoot to 0 8. Lastly set Alarm 8.1. Step > No: Alarm 0 9. Add a new event > Alarm > Alarm In alarm 0 we want to add set variable Variable: can_shoot Value: Save and test that the bullet will fire; also check that only one bullet is being created. 9

10 12. Scores, Lives and Damage To make the game more interesting we will add lives and damage. 1. Create a new object called obj_controller_life, for this game controller will not have sprites attached. 2. Change the depth to Insert the bottom and life sprites from the images folder 4. Add a create event with the following 5. Add a draw event 6. Add a draw sprite (this can be found in the draw tab) 6.1. Sprite: Spr_bottom 6.2. X: Y: Subimage:-1 10

11 7. Set the colour 7.1. Choose a yellow (or any colour that you like) 8. Add a draw score 8.1. X: Y: Add a draw life images 9.1. X: Y: Image: Spr_lives 10. Add a draw health X1: Y1: X2: Y2: Back colour: none Bar colour: green to red 11. Save your work 12. Next add an other event: No More Lives Show the high score Restart the game 13. Add the controller object to the room (it will appear as a blue circle with a question mark) 14. Create a new sprite: using the second explosion sprite 15. Add a sound: explosion Create a new object called obj_explosion Add an other event > animation end Destroy the instance 17. Return to the controller and add the following 18. Add an Other event: No more Health Set the health to Play snd explosion two Add a change of instance 11

12 Explosion 2 If you had tested your game you may notice that when the plane runs out of health it gets destroyed. To reset the plane to the screen go to obj_explosion2 and add the following. 1. Add a other event called animation end 2. Add a sleep 3. Create an instance of obj_myplane 3.1. check relative 4. set the lives to -1 (relative) You have now created a very basic scrolling shooter. However we are not finished, we need to now add some more complexity to the game. Creating a Controller_enemy 1. Create a new object and call it obj_controller_enemy 2. Add a Create event 2.1. Create instance Object: Obj_enemy X: random(room_width) Y: Create instance Object: Obj_enemy X: random(room_width) Y: Set Alarm 12

13 Number of Steps: In alarm no: Alarm 0 3. Add an Alarm event for Alarm Create instance Object: Obj_enemy X: random(room_width) Y: Set Alarm Number of Steps: In alarm no: Alarm 0 13

14 More Enemies To make this game harder three more enemy planes are going to be added. The second enemy plane will shoot a bullet straight down. The third will shoot a bullet at the plane. The fourth enemy will fly up from the bottom of the screen, making it the hardest enemy to avoid or shoot. Bullet for Enemy 1. Insert another bullet and call it spr_bullet_enemy 2. Edit the sprite so that it is smaller than the previous bullet 3. Right click on obj_bullet and select duplicate 4. Call it obj_enemybullet 5. Change the sprite to the smaller bullet 6. Change the vertical speed to 8 7. In the step event 7.1. Change the test variable Variable : y Value: Operation: Greater than 8. Add a collision event with the obj_myplane 8.1. Set health to relative Destroy the instance of the bullet 8.3. Play explosion sound 9. 14

15 Enemy 2 1. Insert a new sprite > spr_enemy 2 2. Right click on object_enemy1 and select duplicate 3. Change the sprite to spr_enemy 2 and call it obj_enemy2 4. In the objects step event add the following 4.1. Add chance Sides: Create instance Object: Obj_enemybullet X: Y: Relative 5. In the collision with the bullet 5.1. Set the score, change from 5 to 10 Bullet 2 1. Right click obj_enemy_bullet and select duplicate 2. Change the name to obj_enemybullet2 3. In the create event add the following 3.1. Test instance count Object: Obj_myplane Number: Operation: Larger than 3.2. Move towards point X: Obj_myplane.x Y: Obj_myplane.y Speed: Else 3.4. Vertical Speed Set vertical speed to 8 Enemy 3 1. Insert the third plane sprite and call it > spr_enemy3 2. Duplicate obj_enemy 2 3. Rename it > obj_enemy3 15

16 4. Change the sprite to spr_enemy3 5. As this is the third enemy if we will change the score to In the step event change the following 6.1. Change the chance to 80, this will make the bullet harder to avoid 6.2. Also change the create instance to Obj_enemybullet2 Enemy 4 1. Right click on obj_enemy3 and duplicate 2. Rename the duplicated object > obj_enemy4 3. Add the correct enemy sprite 4. In the create event 4.1. Set the vertical speed to 4 5. In the step event 5.1. Add a test variable Variable: Y Value: Operation: Smaller than 5.2. Jump to position X: Random(room_width) Y: Room_height Add a collision with the my plane object 6.1. Add a jump to position X: random(room_width) Y: room_height add a collision with the obj_bullet 7.1. Add a jump to position X: Random(room_width) Y: room_height Set score to relative 40 Enemy Controller 1. Open the enemy controller > obj_controller_enemy 2. Add a create event 16

17 2.1. Add set alarm Number of Steps: In alarm no: alarm Add set alarm Number of Steps: In alarm no: alarm Add set alarm Number of Steps: In alarm no: alarm 3 3. Add an alarm event > alarm Create instance Object: obj_enemy X: Random(room_width) Y: Add set alarm Number of Steps: In alarm no: alarm 1 4. Add an alarm event > alarm Create instance Object: obj_enemy X: Random(room_width) Y: Add set alarm Number of Steps: In alarm no: alarm 2 5. Add an alarm event > alarm Create instance Object: obj_enemy X: Random(room_width) Y: room_height Add set alarm Number of Steps: In alarm no: alarm 3 6. Add the object to the room, and delete any enemy planes already in the room. 17

18 7. Save and test. Enemy planes should come at random times. Check and make sure all 4 planes enter the screen. Finishing the Game You have now finished your first scrolling shooter. At this stage to finish you can add any finishing touches you would like. 18