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I'm really stucked. I couldn't understand what does Vector3 state.

When I look Unity Vector3 documentation it says

Representation of 3D vectors and points.

According to this sentence, a Vector3 can state a point or a vector in space.

But When I go into other documentation about Vector3 it really confused me.

For example When I look Vector3 Constructor documentation it says

Creates a new vector with given x, y, z components.

So that means Vector3 states a vector.

But When I look Debug.DrawLine(Vector3 startpoint, Vector3 endpoint) it says startpoint and lookpoint are points in world space. So according to this, Vector3 is a point not a vector

I can increase the examples.

For example when I go into transform.position documentation it says,

The world space position of the Transform.

So it says Vector3 is a position(that means point. I think you can't state a position with Vector)

But when we try to change a position of gameobject with transform.position we again use Vector3 and that state a vector.Because you can't change position of a gameobject with point. You could use Vector

So, what does a Vector3 state ?

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1 Answer 1

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A Vector3 is a set of 3 float values: x, y, and z. These 3 values can represent whatever you want, but usually are used to represent the three axes of either a position, a vector, or a euler rotation.

You generally should be able to tell what a Vector3 represents from context/variable naming. It's important to make the context clear, to avoid mistakes like this:

Vector3 a = transform.position;
Vector3 b = transform.eulerAngles;
a += transform.forward * speed * Time.deltaTime;
b += rotationSpeed * Time.deltaTime;
//oops, we mixed these up! we should have used better variable names!
transform.position = b;
transform.eulerAngles = a;

Your question is analogous to asking "what does a float represent"? A float simply stores a floating-point value; it isn't inherently a distance or a speed or a time or a weight or any other specific type of unit. The meaning of the value is taken from context, e.g.

float distance = Vector3.Distance(point1, point2);
float time = Time.time;
float speed = 5.5;
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  • \$\begingroup\$ Okay I think I got it. Basically What you saying is Vector3 is just three float value. But how come three float value can represent a Vector ? Don't we need at least two point in space to make a Vector ? andhHow can I learn which method represent position, vector or euler rotation ? \$\endgroup\$ Commented Apr 30, 2021 at 0:38
  • \$\begingroup\$ A vector is formally defined as a quantity having direction and magnitude. That definition does not require defining specific start or end points. As I said in the answer, you should be able to determine how the Vector3 is being used from context. \$\endgroup\$ Commented Apr 30, 2021 at 2:01
  • \$\begingroup\$ For example, if we have a point A at (2,2,2) and a point B at (3,3,3), the vector from A to B is (1,1,1). If we have point C at (5,5,5) and point D at (6,6,6) the vector from C to D is also (1,1,1). Those are distance vectors, but the specific start and end points aren't part of the definition. We can also define other quantities, such as velocity, using vectors. \$\endgroup\$ Commented Apr 30, 2021 at 2:13
  • \$\begingroup\$ Thanks for your explanation. Now I understood \$\endgroup\$ Commented Apr 30, 2021 at 3:08
  • \$\begingroup\$ You can think of vector as a point offset away from 0,0,0 then you take that "line" and move it to start from whatever initial point you like. In other words vector is a point away from wherever you choose to begin to "count". \$\endgroup\$ Commented Apr 30, 2021 at 10:12

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