Space Invaders Programming (BlitzPlus)

[Guest]

I have been searching through it and cannot find the probel. Maybe I should just submit it to soem random Blitz dudes at the Blitz website and see what they say?

I might be best if you just posted the problem area of your code next time... it would cut down in the search and destroy crap. Hmmm... Well actually, we might need to know varaible declarations.... I don't know.

I don't know WHERE the problem is, so i could not do that. Add anyway, what good is it if you do not know if I even make certain variables global, loaded the images that I was trying to draw, ect.

lol cool 3dish

3 "dish" O.o
3D-ish ? o.o

[Guest]

Not for the first time, Marauder has stayed up with me at 12:52 and helped me sort out my garled program. Now, it went from not even displaying enemies, to generating, moving, and exploding enemies. Where all my errors were was the function enemy(). I wasn't understanding that when I typed

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for enemy.enemy = each enemy

meant everything under it would not do anything if there were no enemies, and under it was the function to create teh enemies. There for, they wouldn't draw. The was the main problem. I alse had a few minor problems making the things explode when hit.

Next, I must make the enemies shoot.

[MarauderIIC]

12:52 in *your* time zone :) 1:52 here.

[Guest]

OMG. As usual, I have ANOTHER problem. i would appreciate any help i can get.

The problem is, when in debug mode, my game randomly shots off and highlights

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If bullet\from = 2

from my collision function, and an error box appears that says: object does not exist. Here's all of the code that i think may be screwed up:

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Function enemy_fire()

	If able_to_shoot = 1 Then 
		PlaySound enemy_bullet_snd 
		createbullet(2)
	EndIf
	
End Function
	
Function createbullet(from)

If from = 1 Then
Bullet.bullet = New bullet
	Bullet\x = player\x + 15
	Bullet\y = player\y + 5
	bullet\from = 1
	bullet\frame = 0
	bullet\draw = 1
EndIf


If from = 2 Then
For enemy.enemy = Each enemy
Bullet.bullet = New bullet
	Bullet\x = enemy\x + 15
	Bullet\y = enemy\y + 32
	bullet\from = 2
	bullet\frame = 0
	bullet\draw = 2
Next
EndIf 

End Function

Function collisions()
For enemy.enemy = Each enemy
	If ImagesCollide (player_sheet,player\x,player\y,player\frame,enemy_sheet,enemy\x,enemy\y,enemy\frame) Then 
		PlaySound enemyexplode_snd 
		enemy\active = 0
		explosion.explosion = New explosion
			explosion\frame = 0
			explosion\x = enemy\x
			explosion\y = enemy\y
			player\life = player\life - 20
		EndIf

	
For bullet.bullet = Each bullet

If bullet\from = 1
	If ImagesCollide (enemy_sheet,enemy\x,enemy\y,enemy\frame,small_bullet,bullet\x,bullet\y,0) Then
		PlaySound enemyexplode_snd 
		enemy\active = 0
		explosion.explosion = New explosion
			explosion\frame = 0
			explosion\x = enemy\x
			explosion\y = enemy\y
		Delete bullet
	EndIf
EndIf 
	
If bullet\from = 2
	 If ImagesCollide (player_sheet,player\x,player\y,player\frame,enemybullet_sheet,bullet\x,bullet\y,0) Then
			Delete bullet
			player\life = player\life - 5
	 EndIf
EndIf 


		
Next
Next

End Function

Thanks, anyone that tried to sort this garled code..

[MarauderIIC]

From a quick two-second scan, I bet it's caps-sensitive. You wrote both "bullet" and "Bullet" in your code. And from what you told me about Blitz syntax, Bullet.bullet means that it should be "Bullet/from" not "bullet/from".

[Guest]

In differnt functions I did:

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For Bullet.bullet = each bullet

BUT, in the end of those functions, I also wrote:

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Next

ending that loop. But in a DIFFERNT function (collisions), I wrote:

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For bullet.bullet = Each bullet 

not capital.
So that cannot be the problem....can it?

[MarauderIIC]

As long as you were consistent within the context (look that one up).

You were inconsistent here:

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Bullet.bullet = New bullet
   Bullet\x = enemy\x + 15
   Bullet\y = enemy\y + 32
   bullet\from = 2
   bullet\frame = 0
   bullet\draw = 2
Next

Isn't the variable in that context 'Bullet' ? That's why the first two statements work. You should try to be consistent throughout your code.

The C++ 'standard' is to name classes with a capital first letter and then use humpBack [notation]. The C 'standard' was [a] capital [first] letter and [then] '_' for spaces [instead of a capital letter immediately following where the space would be].
[Ex: (C++: theVariable, C: the_variable)]

You might consider naming your types with a capital first letter and variables with lowercase first [letter].

For example,

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class PlayerTotallyOwns {
/* ... */
};

/* ... */

PlayerTotallyOwns heSureDoes;
//PlayerTotallyOwns is the user-defined variable type (ie, a class),
//heSureDoes is the variable.

Edit: Wow, I write in shorthand. Fixes for clarification are in []'s because I wanted to preserve the reason for this edit. :)

[Guest]

You're right, Marauder. Iw as looking at a differnt place. sorry.

Anyway, I'm not AS dumb as I thought. I got it to work! This is what my completed function looks like now, incase any of you want to know:

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Function collisions()
For enemy.enemy = Each enemy
	If ImagesCollide (player_sheet,player\x,player\y,player\frame,enemy_sheet,enemy\x,enemy\y,enemy\frame) Then 
		PlaySound enemyexplode_snd 
		enemy\active = 0
		explosion.explosion = New explosion
			explosion\frame = 0
			explosion\x = enemy\x
			explosion\y = enemy\y
			player\life = player\life - 20
		EndIf
	
For bullet.bullet = Each bullet

If bullet\from = 1
	If ImagesCollide (enemy_sheet,enemy\x,enemy\y,enemy\frame,small_bullet,bullet\x,bullet\y,0) Then
		PlaySound enemyexplode_snd 
		enemy\active = 0
		explosion.explosion = New explosion
			explosion\frame = 0
			explosion\x = enemy\x
			explosion\y = enemy\y
		Delete bullet
	EndIf
EndIf 
	
Next 
	
For bullet.bullet = Each bullet
If bullet\from = 2
	 If ImagesCollide (player_sheet,player\x,player\y,player\frame,enemybullet_sheet,bullet\x,bullet\y,0) Then
			Delete bullet
			player\life = player\life - 5
	 EndIf
EndIf 

Next
Next

End Function

Wow, that means that the above screen shots are already inaccurate! I must be moving at a pretty good pace?

[JS Lemming]

Your problem did not lay in conventions. You deleted the bullet in the following code and later tried to access it. That's like accessing a dead pointer.

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If bullet\from = 1 
   If ImagesCollide (enemy_sheet,enemy\x,enemy\y,enemy\frame,small_bullet,bullet\x,bullet\y,0) Then 
      PlaySound enemyexplode_snd 
      enemy\active = 0 
      explosion.explosion = New explosion 
         explosion\frame = 0 
         explosion\x = enemy\x 
         explosion\y = enemy\y
 
       [color=red]Delete bullet [/color]
   EndIf 
EndIf 
    
If bullet\from = 2 
    If ImagesCollide (player_sheet,player\x,player\y,player\frame,enemybullet_sheet,bullet\x,bullet\y,0) Then 
         Delete bullet 
         player\life = player\life - 5 
    EndIf 
EndIf 

Only delete tpye instances at the end of the loop.

[MarauderIIC]

Neat, last I heard he had it working :) But yeah, that's probably more it than caps-sensitiveness.

[Guest]

Wow, you're right, JS lemming, lol. That fixes another problem I was having but didn't yet post, lol. Anyway, I don't actually have a problem right now, but but I do have a few questions. In Blitz, how do you make something return a value without just giving an error? For example, if I try to open the high scores that are in a text document, and it is the first time running the program and there ISN'T a high score file, how would I make it not give an error and shut the program down, but instead print something to the screen or create one?

Oh, and JS Lemming, if you happen to read this, are you okay on the weekend for the interview?

[JS Lemming]

For the error checking use command FileType.

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;if file blaa.txt does not exist, create it
If FileType("blaa.txt") = 0
	tempfile = WriteFile("blaa.txt")
	CloseFile(tempfile)
Else
	tempfile = OpenFile("blaa.txt")
	; do stuff
	CloseFile(tempfile)
EndIf

yeah sure I'm up to the interview. Hopefully.