Buggy Enemy Detection of Surroundings [+Example]

**Blue66** · 6th July 2011, 03:52 PM

Hi guys!

In the last couple of days, I've tried to find a 1 object only method to have enemies that can jump and detect everything around them, without use of PMO or whatever.

And with a combination of two methods that I've found, it's almost perfect! ...yeah almost

The system I have concocted here has a few flaws and I was hoping someone can help me fix it. The enemy seems to act randomly different then he is supposed to.

What I want from the enemy:
- is there a gap in the ground? JUMP
- if there is a ceiling over the ground? DONT JUMP
- collide with walls? TURN AROUND

Not that complicated, but I have no idea why he acts on random and not how I am telling him. Can someone here please take a look at this problem and tell me what's wrong?

www.gungirl2.com/stuff/testenemy.mfa
(if your browser wants to change file extension to .tiff, just rename it back to .mfa)

Your help is very much appreciated!

**MuddyMole** · 7th July 2011, 02:07 AM

I'm very happy to see you're using embedded collision detectors, and not relying on the PMO extension either.
That's what I'd do too.

I don't understand the ceiling detection part at all. Why on Earth are you pasting a detector into the background?
I suspect this is probably the part of your code that you need to redo. The rest appears to work okay.

A few other points:

I generally don't like to use spread values & fastloops, unless there's really no alternative. In this case they're not really needed, and you can address all enemy objects at the same time.

You have an alterable value called "yPos", but it's actually a velocity not a position.
You are adding 0.1 to this velocity (to simulate gravity), but you don't store the enemy's position as a float, so the velocity is always rounded down - meaning that the enemy doesn't accelerate smoothly.

You have duplicate events for each of the three different "blockade" objects. You should give them all a common qualifier, and refer to that in your events instead.

You're not using a fastloop to push the enemy objects out of the ground. This means that if they are moving very quickly, they will appear to sink into the ground and then slowly float back up, instead of instantly stopping when the hit the ground. The same applies to horizontal movement.

**Blue66** · 7th July 2011, 06:33 AM

Thanks for taking the time and looking at my file

The ceiling detector is pasted into the background just for me to see if it has the right height. If I take out the ceiling detection, the enemy would jump through the ceiling and that's not what I want.

The different blockades could be handeled through qualifiers, but I have some values stored in the blockades that sometimes let enemies through, but took that part out for this example.

The fastloops were taken from the original enemy engine - I had it on my hard drive for a time and I can't remember where I got it from. It didn't have any credits, so I'm sorry I can't thank the guy who made it.

You have a solution how I should improve this engine?

**MuddyMole** · 7th July 2011, 04:36 PM

Originally Posted by Blue66

The ceiling detector is pasted into the background just for me to see if it has the right height. If I take out the ceiling detection, the enemy would jump through the ceiling and that's not what I want.

I'm not seeing that.
If I remove that one action, the only time they jump through the ceiling is if it's a blockade object, and that's because your "detect ceiling" events (lines #24 & #25) are only detecting obstacles - not blockades.

The only thing that looks a bit weird to me, is the way they almost walk off the edge before turning around (where there's a gap, but they can't jump because of the ceiling). I'd guess that's just down to the positioning and size of your detectors though.

In case you're interested, I made this: https://skydrive.live.com/self.aspx/Public/PF5.mfa?cid=b1e7ee094271bbda&sc=documents
But I'm bored now, so I probably won't take it any further.