Need help regaring shooting(Urgent)

[Johnny19931993]

I wrote a game using Turing
A UFO is moving across the screen
A tank is moved by left and right arrow and fire is shot using enter key
The purpose is to shoot at the UFO
but when I shoot, the UFO stopped
I was stuck for a long time and I don't know how to solve this problem
Can anyone help me

This is the program:

code:

setscreen ("graphics") const UFO_HEIGHT := 150 const UFO_WIDTH := 130 const TANK_SPEED := 4 var ufo, tank : int var ufo_y : int var move_x : int := 0 var key : array char of boolean drawfillarc (100, 80, 20, 10, 180, 0, 41) drawfilloval (100, 90, 50, 15, 48) drawfillarc (100, 100, 30, 30, 0, 180, 74) ufo := Pic.New (UFO_HEIGHT - 100, UFO_WIDTH - 60, UFO_HEIGHT, UFO_WIDTH) drawfillbox (0, 0, 50, 40, green) drawfillbox (20, 40, 30, 70, green) tank := Pic.New (0, 0, 50, 70) cls proc tank_move     Input.KeyDown (key)     if key (KEY_LEFT_ARROW) and move_x > 0 then         move_x -= TANK_SPEED     elsif key (KEY_RIGHT_ARROW) and move_x + 50 < maxx then         move_x += TANK_SPEED     end if     Pic.Draw (tank, move_x, 0, picMerge) end tank_move loop     setscreen ("offscreenonly")     for ufo_x : 0 .. maxx by 3         Pic.Draw (ufo, ufo_x, 300, picMerge)         tank_move         Input.KeyDown (key)         if key (KEY_ENTER) then             for bullet_y : 70 .. maxy by 10                 drawfilloval (move_x + 25, bullet_y, 10, 10, 41)                 Pic.Draw (ufo, ufo_x, 300, picMerge)                 tank_move                 View.Update                 cls             end for         end if         View.Update         cls     end for end loop

[Tony]

can you describe what is happening inside this loop? Make sure to mention when it starts and how long it takes.

code:

if key (KEY_ENTER) then             for bullet_y : 70 .. maxy by 10                 drawfilloval (move_x + 25, bullet_y, 10, 10, 41)                 Pic.Draw (ufo, ufo_x, 300, picMerge)                 tank_move                 View.Update                 cls             end for         end if

[Johnny19931993]

code:

if key (KEY_ENTER) then  %The output when the user press the enter key             for bullet_y : 70 .. maxy by 10   %The path and the speed of the bullet                 drawfilloval (move_x + 25, bullet_y, 10, 10, 41) %Draw the bullet                 Pic.Draw (ufo, ufo_x, 300, picMerge)  %Draw the UFO                 tank_move  %Draw and control the tank                 View.Update                 cls             end for         end if

[Tony]

Let me try to rephrase the questions.

Inside that loop, how many times will the UFO be drawn?
List all position(s) (X/Y center) of the UFO, while inside that loop.

[Johnny19931993]

Oh..I get it...
I only drew the UFO once in this loop
And it's at the same position repeating until the fire is gone
So how can I fix this problem?

[Tony]

Good.

Now the problem has to do with the fact that you have multiple loops nested, and they are doing different things. The fact that you use tank_move in multiple places should be a clue that the design of your game loop is likely not ideal.

Keep in mind what a for loop really is.

code:

for i : 1 .. 10 end for

is the same as

Turing:

var i : int := 1 loop    exit when i = 10    i += 1 end loop

You already have a loop, so you can take out the for-loops inside, and rewrite them to use tank_move just once (and only one View.Update, and only one cls).

Also, using setscreen ("offscreenonly") inside a loop is kind of silly. Setting it once is enough.

[Johnny19931993]

Oh...I see
Thanks

[Johnny19931993]

I changed my game and this is the result
but the shooting seems it bit wierd
It requires the player to press and hold the enter key while shooting
and when I release the enter key and press it again
it starts off again at the place where it disappears
How can I fix this problem?

Turing:

setscreen ("graphics,offscreenonly") const UFO_HEIGHT := 150 const UFO_WIDTH := 130 const TANK_SPEED := 7 const UFO_SPEED := 5 var ufo, tank : int var ufo_x : int := 0 var ufo_y : int var move_x : int := maxx div 2 - 25 var bullet_y : int := 70 var any_key : string (1) var key : array char of boolean drawfillarc (100, 80, 20, 10, 180, 0, 40) drawfilloval (100, 90, 50, 15, 48) drawfillarc (100, 100, 30, 30, 0, 180, 74) ufo := Pic.New (UFO_HEIGHT - 100, UFO_WIDTH - 60, UFO_HEIGHT, UFO_WIDTH) drawfillbox (0, 0, 50, 40, green) drawfillbox (20, 40, 30, 70, green) tank := Pic.New (0, 0, 50, 70) cls proc tank_move     Input.KeyDown (key)     if key (KEY_LEFT_ARROW) and move_x > 0 then         move_x -= TANK_SPEED     elsif key (KEY_RIGHT_ARROW) and move_x + 50 < maxx then         move_x += TANK_SPEED     end if     Pic.Draw (tank, move_x, 0, picMerge) end tank_move randint (ufo_y, maxy div 2, maxy - UFO_HEIGHT) proc ufo_move     ufo_x += UFO_SPEED     Pic.Draw (ufo, ufo_x, ufo_y, picMerge)     if ufo_x = (maxx div UFO_SPEED) * UFO_SPEED then         ufo_x := 0         randint (ufo_y, maxy div 2, maxy - UFO_HEIGHT)     end if end ufo_move proc shoot     Input.KeyDown (key)     if key (KEY_ENTER) then         bullet_y += 10         drawfilloval (move_x + 25, bullet_y, 10, 10, 41)         if Math.Distance (ufo_x + 50, ufo_y + 50, move_x + 25, bullet_y) < 60 then             ufo_x := 0             randint (ufo_y, maxy div 2, maxy - UFO_HEIGHT)             bullet_y := 70         elsif bullet_y = (maxy div 10) * 10 then             bullet_y := 70         end if     end if end shoot loop     tank_move     shoot     ufo_move     View.Update     cls end loop

[Tony]

This looks much better!

The problem with shooting now, is that everything is inside the if key (KEY_ENTER) then block. You could use a variable to keep track if the key has been previously pressed.

Turing:

var bullet_on_screen : boolean := false Input.KeyDown (key) if key (KEY_ENTER) then    bullet_on_screen = true end if if bullet_on_screen then    bullet_y += 10    drawfilloval (move_x + 25, bullet_y, 10, 10, 41)    ...

You'd have to reset the flag back to false when you don't want the bullet to fly.

Also, why is the same variable used for both the bullet's and tank's X location?

[Johnny19931993]

Yes, that's another problem too
I want the bullet to be shot at the place where the tank is
But i can't do it except making the x value of both the bullet and the tank the same

[Tony]

you could use a different variable. bullet_x perhaps?

[Johnny19931993]

But what value does bullet_x has
If it's the same as tank_x, then it won't make any difference
How can I cut it's connection with tank_x after it's shot?

[Tony]

code:

tank_x = 10 bullet_x = tank_x tank_x = 15

what is the value of tank_x and bullet_x?

[Johnny19931993]

I see...
But because of the loop, the x value of the tank keep changing every time it loops
So the x value of the bullet keep changing too...

[Homer_simpson]

setscreen ("graphics")

const UFO_HEIGHT := 150
const UFO_WIDTH := 130
const TANK_SPEED := 4
var ufo, tank : int
var ufo_y : int
var move_x : int := 0
var key : array char of boolean

drawfillarc (100, 80, 20, 10, 180, 0, 41)
drawfilloval (100, 90, 50, 15, 48)
drawfillarc (100, 100, 30, 30, 0, 180, 74)
ufo := Pic.New (UFO_HEIGHT - 100, UFO_WIDTH - 60, UFO_HEIGHT, UFO_WIDTH)

drawfillbox (0, 0, 50, 40, green)
drawfillbox (20, 40, 30, 70, green)
tank := Pic.New (0, 0, 50, 70)
cls

proc tank_move
Input.KeyDown (key)
if key (KEY_LEFT_ARROW) and move_x > 0 then
move_x -= TANK_SPEED
elsif key (KEY_RIGHT_ARROW) and move_x + 50 < maxx then
move_x += TANK_SPEED
end if
Pic.Draw (tank, move_x, 0, picMerge)
end tank_move
var bullet_y : int := 0
var bullet_fired := false
loop
setscreen ("offscreenonly")
for ufo_x : 0 .. maxx by 3
Pic.Draw (ufo, ufo_x, 300, picMerge)
tank_move
Input.KeyDown (key)
if key (KEY_ENTER) and not bullet_fired then
bullet_y := 70
bullet_fired := true

end if
if bullet_fired then
drawfilloval (move_x + 25, bullet_y, 10, 10, 41)
bullet_y += 3 %bullet speed
if bullet_y > maxy then
bullet_fired := false
end if

end if
View.Update
cls
end for
end loop