Calculating distance

[Graylord]

So I am mathematically calculating the distance between a character and a target location. Dealing with positive numbers is no problem, but I am unsure of how to manage the negatives. The Map is placed at 0,0,0 so there will be equally much negative vectors as positive, so I need to work this out.

Is there perhaps a way to get the total amount between two numbers other than subtracting (since that doesn't work with negatives)

I tried doing abs() to make it all positives, but there a logic issue with that. The calculation is not correct if one is positive and the other negative, IE the character is at -1000 and the target is at x 1000, it believes the target is reached since it subtracts 1000 with 1000.

Or should I perhaps do some conditions, and subtract double the amount (to accomodate being negative)? It will have to be a ton conditions though.

Edit: I think I've gone about it the wrong way, I'll just subtract the negatives then do an abs() on the result.

[UnrealEverything]

Uhm,

aVector = Target.Location - Character.Location;
VSize(aVector);

?

[Graylord]

Could you elaborate on VSize? How does it work and what does it give?

I need an int or a float that gives the total distance.

[nonder]

I usually use Vsize too. But i found this on google:

Math:
Vector1=(1,2,0) 
Vector2=(-2,3,5)

sqrt((1 + 2)^2 + (2 - 3)^2 + (0 - 5)^2)
= sqrt(9 + 1 + 25)
= sqrt(35)

Unrealscript:
VectorCache = Vector1 - Vector2;
Distance = VSize(VectorCache);

Distance is float or int...
Vector 1 is usually target and Vector 2 location of pawn...

[Wormbo]

Use VSize, it's exactly what you "found on google".

[Graylord]

TargetDistance = Abs(PawnLocation.X - TargetLocation.X) + Abs(PawnLocation.Y - TargetLocation.Y);

Wouldn't this also work? (I want to ignore Z, that's why it's missing, though it should theoretically just be adding another abs with it.)

[UnrealEverything]

Well that's only half way there.
Draw that on a piece of paper or something and you will see that you need to use Pythagorean theorem at some point.

You also don't necessarily need the sqrt.

(If you want to ignore z then there's also a VSize2D function which still takes a normal vector [with z] as a parameter)

[Graylord]

Ah I see.

What do you mean with Z as a parameter? I can't find any obvious examples of it, and there seems to be no references on UDN.

But I should theoretically be able to just use VSize if I nullify the Z on both vectors right before the math, right?

[Wormbo]

Use VSize2D if you want to ignore the Z component. I recommend reading up on vector operations in general, as you seem to be a bit lacking in that area.

[Graylord]

So I can see the reference to VSize2D there, but I cannot see how you would use it to just simply avoid Z. Why is using VSize with two vectors that has 0 in the Z unfeasible?

[Angel_Mapper]

It's what VSize2D does, ignores the Z component.

TargetDistance = VSize2D(PawnLocation - TargetLocation);

[Wormbo]

N.B.: The expression "Vector2 - Vector1" calculates a new vector such that if you put the starts of the two vectors together, the resulting vector goes from the first vector's end to the second vector's end. And since location vectors basically all have their starts stuck together at the origin, the end-to-end vector is exactly what you want to calculate the length of.

[Infinite_Loop]

For an optimization if you are trying to compare 2 distances or compare to a fixed distance you can use VSizeSQ which removes the square root from the distance equation. This is a nice little optimization if you are checking distance every tick. ex. to check which of 2 actors is closer,
dist1 = vsizesq(location - actor1.location)
dist2 = vsizesq(location - actor2.location)

if(dist1 > dist2)
//actor 2 is closer.

the the values will be squared but the actual distance is irrelevant. similarly if you want to see if something is within 25 uu. you can just check if(dist < 625) //25^2