following a path? help please :D!

[munt4life]

Hey i was wondering what i would have to do if im controlling a circle, and there is another circle, how would i get the circle to follow me, i am making a game where theres many obstacles and i was thinking in one part there would be a couple "monsters" chasing me, so depending on where i move they would go towards me as well. Any feedback would be helpful thanks!

[A.J]

There are many ways one could implement enemy's chasing you. One naive way to do so is to have the enemies move towards your position at every iteration; to do this, you measure the angle at which the enemy needs to move at, and increase its x and y position (assuming this is a 2D game) accordingly. The downside of this method is that the enemies don't traverse around obstacles (instead they just try going through them).

To account for obstacles, however, you need to utilize a path finding algorithm. The one I recommend is the A* ('A star') algorithm (I'll leave it to you to read up on it). If you have any questions regarding it, feel free to ask us here.

[munt4life]

im assuming i need trig?

[Insectoid]

Yes. It's fairly simple though; since you're only making right triangles, you can get away with sine law.

[DemonWasp]

Actually, that particular algorithm doesn't even need sine law (and is faster without it). You just need to remember a few things about similar triangles and Pythagorean theorem.

[Raknarg]

or you could use
x + cosd (theta) and
y + sind (theta)

[munt4life]

ok so i tried doing something like
theta := arctan((y1-compy)/(x1-compx))
compx+=speedx(cos(theta))
compy+=speedy(sin(theta))

im getting an error on subscripts im pretty sure my math is right what should i fix?

[A.J]

I thought you wanted to enemies that are chasing you to avoid obstacles. In which case, the method you are currently attempting to code (i.e. the first approach I described in my previous post) doesn't cut it.

[munt4life]

im trying to get the actual moving to work for now then after i will create restrictions i defined all those variables why does turing say speedx and speedy cannot have subscripts.

[A.J]

Even if you have the enemies move towards you at every iteration in this fashion, you can't modify it to avoid obstacles as well; the enemies will just keep trying to come towards you even if there's an obstacle in the way.

[munt4life]

Could you please tell me why my code isnt working please so i could then move on to such a problem

[A.J]

I don't see any code here to help you with/.

[munt4life]

anyone?

[munt4life]

k so now i have this
i tried a similar triangles method.
var bCoordx := x - compx
var bCoordy := y - compy
var d : real := Math.Distance (x, y, compx, compy) % computer finds out input position to determine where to move
var sx := 10 * bCoordx / d
var sy := 10 * bCoordy / d

then i have a bunch of stuff in a procedure blah blah so i have
drawfillbox (compx, compy, compx + 10, compy + 10, red)
how would i make the compx and compy change according to this? im confused please help

[Raknarg]

Depends on whether or not you want it to avoid obstacles. Is this the case?