Vector Math in Unreal

[SeldinG]

@jwatte

@SeldinG

Both the Dot Product and Cross Product are optional in Unreal, but natively it simply multiplies the coordinate pairs together to produce a new vector like so:

Your confusion is largely about the language binding, not the math.

Unreal has chosen the * operator to mean “elementwise multiplication.”
To get the dot product, or the cross product, you use the VectorDot() or VectorCross() functions.

@SeldinG

I don’t have to do any trig.

You should almost never have to do any trigonometry. If you’re doing character- or camera-relative movement, the character, or the camera, has a world transform, which has inherent “forward” and “right” and “up” vectors that you can use for movement. If you need to know whether two objects are “pointing at” each other, calculate the dot product between their “forward” vectors and compare the magnitude (negative means “pointing at each other,” positive means "pointing in the same direction.)
And so on.

Trigonometry is only really needed when your input is in “compass units” (either radians or degrees,) and you should almost never need to actually use compass units.

Thank you, that is very helpful. I’m still a little confused, but closer than I was.