[JASS] I hate vector mathematics!

[Element of Water]

public method projectToPoint (real x, real y, real z, real speed)
        {
            real dx = x - this.xP,
                 dy = y - this.yP,
                 dz = z - this.zP,
                 len = SquareRoot(dx * dx + dy * dy + dz * dz);
            
            this.xV = speed * dx/len;
            this.yV = speed * dy/len;
            this.zV = speed * dz/len;
        }

Here we have a nice bit of Zinc code. It attempts to project a missile towards a point by setting its velocity to the right values. One problem: it seems to randomly not work sometimes. Any ideas where I'm going wrong with the calculations?

PS: Yes, I'm sure the missile moves based on the velocity correctly, and xP/yP/zP are all set to valid values.

 

[SlayerII]

well this looks quite good, maybe you explain how it is sometimes not working. Maybe you test if it is working without z coordinates

 

[Element of Water]

Nope, commented out all the z stuff and now it just doesn't work right in less dimensions. The exact circumstances are that I have a function to make it follow a unit by using this function to make the missile travel in the direction of the target. It works to follow one unit, but then I change the target and poof. The velocity remains at [0, 0, 0] no matter where the unit goes or what speed I use.

 

[SlayerII]

hmm well that means that HERE shouldn't a mistake. I am using something very similar to this for my missles, and I never had a bug.
That you get [0,0,0] may be a clue that something which gives data to the function isnt working like it should.

edit: i remembered that i once had a bug that i just got a very small speed, maybe you get it just 100 times smaller or something

 

[Element of Water]

Lol. I put 0 into the speed. It was a remnant of me cancelling the homing a awhile ago, and I forgot to plug the right variable into it . I think I need some sleep. Goodbyes. Thank you and +rep for trying to help.

 

[SlayerII]

well most mistakes happen at simple things, cause when you doing something complex, you concentrade more.

 

[HINDYhat]

Two things:
- Remember to scale your speed value based on the period of your update function. That way, speed will be the same regardless of if you change the period of your function. Otherwise, that wouldn't be the case.

- You should add 0.01 to len. It's possible that you inadvertently set dx, dy and dz equal to 0. It's good practice for this sort of thing.

Yay vector math! Need any more help and just ask me.

 

[Element of Water]

1. Yeah, I do. The missile system is practically finished. It's just in testing stage.

2. There's only a very miniscule chance of that happening, and I don't think it's worth any inaccuracy.

Yay vector math! Need any more help and just ask me.

Lol. I'll be sure to ask you in the future .