Shooting Multiple Shots

[chaos]

I want to be able to fire multiple shots, but I can only figure out how to shoot one shot at a time. I was wondering what ways there are to do this (ie. a particle engine)?

[crossley7]

a simple way is to duplicate your variables or convert them to arrays and have an array of boolean that will say whether it is in the air or not. Then just loop around your array and depending on how you do it, you can have up to n shots if n is the size of the array.

It really depends how you have it set up to help you much with getting multiples

[Insectoid]

You'll want an array of bullets, yeah. I suggest you calculate the maximum possible number of bullets on the screen at a time. This is how big your array should be.

[chaos]

I want to limit it to about 10 bullets on screen at a time. Also, is it possible to do this using a particle engine for bullets?

[Insectoid]

Uh, why? Bullets move just like characters. Particle engines are for like, smoke & stuff like that.

[chaos]

So, is creating an array each for the number if bullets, the bullet's x-coordinate, and the bullet's y-coordinate the correct way to go?

[Insectoid]

Have a look at records. There should be something about them in the Turing Walkthrough.

[chaos]

I took a look at records and this is what I have come up with. I have one problem. The error message says there is no value for the variable in the line where the bullet is drawn.

Turing:

setscreen("offscreenonly") var x:int:=0 var y:int:=maxy div 2 var ship:int:=Pic.FileNew("G:/Turing Game/SpaceShip.bmp") var bullet:int:=Pic.FileNew("G:/Turing Game/Bullet.bmp") var count:int:=0 type Bullet: record x,y,speed:real bullet:boolean end record var Shoot:array 1..10 of Bullet for a:1..10     Shoot(a).bullet:=false end for var chars:array char of boolean loop    Input.KeyDown (chars)     if chars (KEY_UP_ARROW) and y+27<maxy then         y+=1                end if     if chars (KEY_DOWN_ARROW) and y>0 then         y-=1     end if     if chars (' ') then         count+=1         if count=11 then             count:=1         end if         for bulletcheck:1..10             if bulletcheck=count then                 Shoot(bulletcheck).bullet:=true             end if             if Shoot(bulletcheck).bullet=true then                 Shoot(bulletcheck).x:=67                 Shoot(bulletcheck).y:=y+8             end if             Pic.Draw(bullet,round(Shoot(bulletcheck).x),round(Shoot(bulletcheck).y),picCopy)             Shoot(bulletcheck).x+=5         end for                             end if             Pic.Draw(ship,x,y,picCopy)     View.Update     delay(10)     cls end loop

[mirhagk]

You have this organized very strangely. When you shoot you want to do all that setting of it's values and stuff in one section, and in a different section you check if it's alive and draw it if it is.

Right now your drawing all the bullets that don't exist as soon as you hit the space bar.

[chaos]

@mirhagk: Thanks. I fixed the problem.

Here is the fixed code. Though I need some help on delaying the movement of the bullet from the movement of the ship.

Turing:

setscreen("offscreenonly") var x:int:=0 var y:int:=maxy div 2 var ship:int:=Pic.FileNew("G:/Turing Game/SpaceShip.bmp") var bullet:int:=Pic.FileNew("G:/Turing Game/Bullet.bmp") var count:int:=0 type Bullet: record x,y,speed:real bullet:boolean end record var Shoot:array 1..10 of Bullet for a:1..10     Shoot(a).bullet:=false     Shoot(a).speed:=5 end for var chars:array char of boolean loop    Input.KeyDown (chars)     if chars (KEY_UP_ARROW) and y+27<maxy then         y+=1                end if     if chars (KEY_DOWN_ARROW) and y>0 then         y-=1     end if     if chars (' ') then         count+=1         if count=11 then             count:=1         end if         for check:1..10             if check=count then                 Shoot(check).bullet:=true                 Shoot(check).x:=67                 Shoot(check).y:=y+8             end if         end for        end if     for firing:1..10         if Shoot(firing).bullet=true then             Shoot(firing).x+=Shoot(firing).speed             if Shoot(firing).x>maxx then                 Shoot(firing).bullet:=false             else                 Pic.Draw(bullet,round(Shoot(firing).x),round(Shoot(firing).y),picCopy)             end if         end if     end for             Pic.Draw(ship,x,y,picCopy)     View.Update     delay(50)     cls end loop

[mirhagk]

I might be confused as to what you want, but couldn't you just decrease the speed?

[Raknarg]

Turing:

for check:1..10      if check=count then           Shoot(check).bullet:=true           Shoot(check).x:=67           Shoot(check).y:=y+8      end if end for

This xan be shortened to:

Turing:

Shoot(count).bullet:=true Shoot(count).x:=67 Shoot(count).y:=y+8

since that's whats going to happen anyways.

And as for your most recent quetion, there's no need to delya them seperately. Just move them at different speeds.

Also, you're going to encounter one more problem in the future, depending on how you do it. But to make it easier, I'd move every dead bullet to a ludicrous position so they do not get in the way. When I did my spaceship game, it took me a while to figure out why ships were disappearing at random, and its because (again, depending on how you do it) the dead bullets kill ships though they dont move and are not drawn.

[chaos]

I have now included enemies and collision detection (somewhat). The problem is that after you kill the enemy and shoot bullets again in the same location, the bullets disappear without the the presence of an enemy for some time--about less than a second, but noticeable. How can I fix this? Any help is appreciated. I have attached the enemy ship below. Here is my code:

Turing:

setscreen("offscreenonly") var x:int:=0 var y:int:=maxy div 2 var ship:int:=Pic.FileNew("G:/Turing Game/SpaceShip.bmp")   %Spaceship pic (68x27 pixels) var bullet:int:=Pic.FileNew("G:/Turing Game/Bullet.bmp")   %Bullet pic (20x8 pixels) var count:int:=0 var EnemyShip:int:=Pic.FileNew("G:/Turing Game/EnemyShip.bmp")  %EnemyShip pic (77x39 pixels) var background:int:=Pic.FileNew("G:/Turing Game/scrollingBackground.bmp")  %Background pic (2,110x300 pixels) const screenx:=640 const picx:=2110 var backx:int:=0 const eships:=5 %Max # of enemy ships type Enemy:     %Record of variables for enemy ships     record         ex,ey,espeed:real         onoff:boolean     end record var BadGuys:array 1..eships of Enemy %Array for enemy ships for i:1..eships         %Assigning initial values of enemy ships     BadGuys(i).ex:=maxx                 %EnemyShip x-coordinate     BadGuys(i).ey:=Rand.Int(39,maxy-39) %EnemyShip y-coordinate     BadGuys(i).espeed:=Rand.Int(3,5)    %EnemyShip speed     BadGuys(i).onoff:=false end for const shots:=10 %Max # of bullets type Bullet:    %Record of variables for bullets     record         x,y,speed:real         bullet:boolean     end record var Shoot:array 1..shots of Bullet %Array for bullets for a:1..shots          %Assigning unitial values of bullets     Shoot(a).bullet:=false         %Bullet is off("false"=off;"true"=on)     Shoot(a).speed:=5              %Bullet speed end for var chars:array char of boolean loop                                %Main loop     %Drawing the Background     Pic.Draw(background,-backx,0,picCopy)     if backx=picx then         backx:=0     elsif backx+screenx>=picx then         Pic.Draw(background,picx-backx,0,picCopy)     end if         %Spawning the Bad Guys     for e:1..eships         BadGuys(e).ex-=BadGuys(e).espeed         var num:int:=Rand.Int(1,3)         if BadGuys(e).ex<=0 then             BadGuys(e).ex:=maxx             BadGuys(e).ey:=Rand.Int(39,maxy-39)             BadGuys(e).espeed:=Rand.Int(3,5)             if num not=3 then                 BadGuys(e).onoff:=true             end if         end if         if BadGuys(e).onoff=true then             Pic.Draw(EnemyShip,round(BadGuys(e).ex),round(BadGuys(e).ey),picMerge)         end if     end for            Input.KeyDown (chars)     %Movement for the Hero's Ship     if chars (KEY_UP_ARROW) and y+27<maxy then    %Moving Up         y+=5            end if     if chars (KEY_DOWN_ARROW) and y>0 then        %Moving Down         y-=5     end if     if chars (KEY_RIGHT_ARROW) and x+68<maxx then %Moving Right         x+=5     end if     if chars (KEY_LEFT_ARROW) and x>0 then        %Moving Left         x-=5     end if     if chars (' ') then                           %Firing Bullets         count+=1         if count=shots+1 then %Shot Limiter             count:=1         end if         for check:1..shots             if check=count then     %Assigns the values of each bullet, one at a time                 Shoot(check).bullet:=true       %Turns bullet on                 Shoot(check).x:=x+68            %Sets bullet's x-coordinate                 Shoot(check).y:=y+8             %Sets bullet's y-coordinate             end if         end for        end if     for firing:1..shots             %Fires the bullets, one at a time         if Shoot(firing).bullet=true then             Shoot(firing).x+=Shoot(firing).speed    %Moves the bullet by the given speed             if Shoot(firing).x>maxx then                 Shoot(firing).bullet:=false         %Turns the bullet off if it goes off the screen             else                 Pic.Draw(bullet,round(Shoot(firing).x),round(Shoot(firing).y),picMerge)  %Draws the bullet                             end if             for collision:1..eships                 if ((Shoot(firing).x+20>=BadGuys(collision).ex) and ((Shoot(firing).y)<=BadGuys(collision).ey+39) and (Shoot(firing).y>=BadGuys(collision).ey)) then                     Shoot(firing).bullet:=false                     BadGuys(collision).onoff:=false                 end if             end for         end if     end for         Pic.Draw(ship,x,y,picMerge)     %Draws Hero's Ship     View.Update                     %For fluent animation     backx+=5                        %Moves background     delay(50)                        cls                             %Clears screen end loop

[[Gandalf]]

You'll want your array of bullets to be a flexible array. That way, you can increase or decrease the amount of bullets you keep track of depending on whether the bullet still exists.

You can find information on flexible arrays in Part III of the Arrays tutorial from the Turing Walkthrough.

[Insectoid]

I don't think that's strictly necessary [Gandalf]. Flexible arrays are slow. Better to calculate the number of bullets a given character can shoot in the time it takes for a bullet to move across the maximum distance across the screen. If it takes 3 seconds to cross the screen, and you fire one bullet every second, your array needs to be 3 cells (or 4, to be safe). Then you give every character its own bullet array, and you'll have access to as many bullets as you'll need.