My first game - questions & feedback

[PaulFoster]

I'm working on a simple game (might have seen in my book thread)

Here is my current version ufo.mfa

its supposed to be a game like the old arcade vector graphics games (Asteroids, Stellar Castle, Rip Off, etc etc) its my first game so obviously its not good or coded very neatly but its ok. anyway I have questions:-

1:- Currently its set to renew your shields every 1000 points (only 1000 for testing purposes) but there are 2 issues currently

a:- When the shields renew, they are off-center and I cannot seem to position them exactly like the starting ones. which is annoying
b:- For some reason unknown to me, after 2-3 shield renews (ie around 2000-3000pts) the shield renew system goes out of sync.. and instead of renewing the shields at 3000,4000,5000 it might renew them at 3200,4500,5300 ..why??

2:- My "mothership" currently comes on from the right, flies around the player and heads off right again. I've used a path movement to do it, but is there a way of making multiple paths and having it pick a random one?

3:- Sometimes the mothership will shoot when I have 1 shield left and the bullet will go through the shield and kill me. is this a bug with the collision detection or is it a fault in my code? (only seems to happen when there is 1 shield left and even then doesn't happen every time)

Thank you for your help

[Del_Duio]

Question #2:

Yeah, you should be able to assign each active (the mothership, in this case) several different movement types and then you could have code like-

When mothership is out of the play area -> set counter to Random(3)+1
If counter = 1 then set mothership to movement #1
If counter = 2 then set mothership to movement #2
If counter = 3 then set mothership to movement #3

Something like that, I don't have my MMF in front of me now but it's entirely possible.

Question #3:

This to me sounds like it could be an error with the shield equation.
If your code is like this:

If bullet hits the shield and shield > 1 then destroy bullet and set shield power to shield power - 1

Then when your shield power IS 1 the bullet will bypass it and blow up your ship because in this case your shields are only going to protect you if they're anywhere from 2 to max. Just change it to this:

If bullet hits the shield and shield >= 1 then destroy bullet and set shield power to shield power - 1

Or

If bullet hits the shield and shield > 0 then destroy bullet and set shield power to shield power - 1

Again, this is all a guess since I can't open your .mfa.

[PaulFoster]

it won't open? did I upload it wrong?

[PaulFoster]

Hi all, I've been updating the graphics on my first game, just wondered if it would look ok with newer looking graphics but I still seem to have a problem with the collision detection
Sometimes the motherships shot will simply pass through my ship and destroy me even if the shield is up. I guess the problem is in my code, not a bug in fusion but I cannot see the issue. also it doesn't help that it doesn't always do it, just from time to time.

Sadly I cannot upload my mfa to this site as the max size is 1mb and I'm just over that, so here is a link to it http://expirebox.com/download/a70a67...4794d925f.html

If you could maybe tell me where my collision mistake is, it would be really really helpful.

[King_Cool]

Yes, there are 2 problems i can identify.


#1
The shield graphic looks realy nice. Is that from Fusions library?
In any case, animation has got 'holes' in it, making it possible for the UFO shots to 'slip through thew cracks'.



#2
The code for 'Bullet to Ship' collision is loacated before the code of 'Bullet to Shield' collision.
This means its technically posible, at high Bullet speeds, for the Bullet to bypass the shiel and detect a hit with the Ship before detecting a Shild hit ( destroying the Ship by bypassing he Shield ).

You could solve this by switching places so that 'Bullet to Shield' collision is detected before 'Bullet to Ship'.

Another, maybe more sophisticated, solution would be to add a Condition to the 'Bullet to Ship' collision Event: If number of Shields equals 0 ( making 'Bullet to Ship' collision only trigger if there are no shields ). But depending on a potential expansion of the design ( Exampel: shield piercing bullets etc ) this solution might instead be in conflict with the design.

[PaulFoster]

Thanks VERY much for that.

I cannot believe I am so stupid and never realised about the shield, I just wanted a cool transparent overlay kind of shield but now that you pointed it out, yes thats why its doing that. I can't think of any way of stopping it without making the shield solid. shame

as for the other issue, thank you. thats very interesting indeed.

Edit:- on a 2nd reading of your post, I think I understand what you mean about the way of doing the shields, I'll give it a try. thank again for your time

btw the shield graphics was taken from google as I have all the artistic ability of a drunk elephant

[King_Cool]

I am sorry, i seem to have left out something.
Let me try again:

...
SOLUTION ISSUE#1 ( BULLET SLIPPING THROUGH CRACKS )

A
You could 'uncheck' the Shields property called 'use fine detection' which, for all collision detection purposes, turns it into a square box. I wouldnt recomend this as the shield is supposed to be round, but the impact of this descrepency should be relatively minimal.

B
You could create a 'phisical detector' ( a round, invissible, single-colored, non-animated circle... in short a collision mask ) and just superimpose the graphics onto this circle, and have the mask handle all/ any interactions.

C
Or you could do a 'virtual detector', skipping any kind of extra collision mask Object ( lets you keep the single Shield graphics regardlass of "cracks" ).
Have the Bullets calculate the distance from Themselves to the Shield, in an AlterableValue ( example: DistanceToShield_ ), and detect a collision by doing:

+ 'Distance to shield_' is lower than <Range> ( <Range> being the radius of the Shield )
-> Action

...
SOLUTION ISSUE#2 ( BULLET BYPASSING SHIELD )

The code for 'Bullet to Ship' collision is located before the code of 'Bullet to Shield' collision.
This means its technically posible, at high Bullet speeds, for the Bullet to bypass the shiel and detect a hit with the Ship before detecting a Shild hit ( destroying the Ship by bypassing he Shield ).

A
You could solve this by switching places so that 'Bullet to Shield' collision is detected before 'Bullet to Ship'.

B
Another, maybe more sophisticated, solution would be to add a Condition to the 'Bullet to Ship' collision Event: If number of Shields equals 0 ( making 'Bullet to Ship' collision only trigger if there are no shields ). But depending on a potential expansion of the design ( Exampel: shield piercing bullets etc ) this solution might instead be in conflict with the design.

...
"I have all the artistic ability of a drunk elephant"
^ This sounds interesting

[Del_Duio]

I have another possibility for your shield problem:

SOLUTION ISSUE#1 ( BULLET SLIPPING THROUGH CRACKS )

D. Make your shield animation use alpha channels and use the lightest possible setting to "fill in" all the gaps to make it a complete circle. I do similar stuff all the time and if you use the absolute lightest color of the alpha channel it's near invisible and will still register with your bullet collisions.

[King_Cool]

Didnt think of that
Alphas could be used as a supplementary/ additional collision mask, nice

[PaulFoster]

Thanks all for your help. I **think** I've sorted out the issue with the shields by a:- moving the bullet to ship collision further down the list of events and b:- I added a variable S (S for shields.. original huh) and had it 0 at default and 1 when all shields are gone and the ship-shot collision only fires if S=1. I think its working ..well so far.

an unrelated point but something thats nagging at me. This game is about as simple as you're going to get, I can only imagine how complex some peoples games are, and yet look at this screen



see how complex and cluttered its looking? its getting that I'm losing track of what does what. is there a way of tidying it up? putting some parts together or heck, even adding some comment sections saying what part does what?? I think it would help when I start doing more complex games.