Moving object according to backdrops?

[camelman]

I actually have 2 problems I've been trying to figure out for days! Maybe someone could help?

1. How do I get an object to move around platforms that are in its way? Say I have an enemy that can stick to walls, and it's in a square room with a few platforms sticking out of the wall. I can get the enemy to move around in the square no problem, but how would I get it to move around the platforms coming out of the wall? I could probably do this by using detectors, but I'd rather not, any way that is possible?

2. How do I get an object (an arrow for example) to stick to another object (moving target) at the same place it collided with it?

Thanks for any help!

[crusher]

I've been working on a "wall crawler" engine for my latest project and it's working pretty good. Check it out:
http://crusher.metalgear.googlepages.com/zoomer2.mfa

Basically what it does it check 3 different spots for collision (or the lack of) to determine which direction to switch to. It only moves the enemies one pixel at a time though so I'm using a fastloop to move them four times faster.

Now, it's not a very efficient engine in that I have to constantly set the Collision A/B/C values during the loop and I have yet to come up with a better solution... I would be grateful if someone could suggest a better way of doing this.

Either way this just might be what you need. Oh and sorry, I haven't commented it. Just ask if you don't understand and I'll try to help.

[Sieg]

1. To figure this out, I would like to know how you move the enemy around in the square room (you say you can do that no problem).


2.
On "Arrow" collides with "Target"
-> set valueA of "Arrow" to: "Xarrow" - "Xtarget"
-> set valueB of "Arrow" to: "Yarrow" - "Ytarget"
-> set flag 0 of "Arrow" on

Flag 0 of "Arrow" is on
-> set Xposition of "Arrow" to "Xtarget" + valueA
-> set Yposition of "Arrow" to "Ytarget" + valueB

[camelman]

Well there are probably simpler ways to move it in a square, but most of the time I will just use values to move its x,y positions, and another value to tell the object how long to move in that direction.

value A=1
Value B<50
-set xpos("object")to("object")-1
-Add 1 to Value B

(I use the same event for other directions, but I don't feel like typing everything down, you get the point :P )

Value A=1
Value B>=49
-Set Value A to 2
-Set Value B to 0

Something like that atleast. Thanks for the "arrow" expression I'll have to try that out in a min.

[Sieg]

Why dont you use the built in pathmovement?

[camelman]

Because path movement is strictly following a given path, with no alternatives. If I make an event that will move that enemy differently, it will forever be off course, among many other things. Not like my above expressions are much different, but those are very simple movements. It's just more manageable to use expressions imo. That and I don't like using the built in movements I'd rather do it on my own O_o

[Sieg]

Well then it would be difficult without using invisible detector objects. It can be done in many different ways, depending on how your engine works.

Are the platforms square too? are there any slopes?
Complex, round shapes would make this harder to do.
Are your levels dynamically loaded? are they tiled?

Maybe you should post a picture of what the level looks like. Or upload your .mfa file, cause we are working blind here :S

[crusher]

Did you have a chance to try my example yet? I forgot to mention that it's detectorless, doesn't rely on any pre-built paths and works with slopes too. It's basically works just like the enemy "Zoomer"in the Metroid series.

[Sieg]

Wow crusher! I never knew of the existence of the Collisionmask testing That's very valuable! I learned something

[crusher]

Glad I could be of service somehow. Collision masks are very useful and because of them there really are no reasons to use detectors anymore.