Как найти расстояние между объектами unity

Introduction

In this arti­cle we will see dif­fer­ent ways to cal­cu­late the dis­tance between two objects in Uni­ty, this can be use­ful for exam­ple to know how far is the char­ac­ter from a cer­tain point of the sce­nario or to acti­vate mech­a­nisms when the char­ac­ter is at a cer­tain distance.

Setting up the scene

Let’s make a very sim­ple scene that will have two spheres with 3D texts to indi­cate the num­ber of the sphere and the dis­tance between them.

The cam­era will have assigned the Script named “Dis­tances” which is the one that will cal­cu­late the dis­tance and write the val­ues on the screen. As an extra, we’ll add a Line Ren­der­er com­po­nent to draw a line from one object to another. 

In fig­ure 2, we see that there are fields for both objects and for the dis­tance indi­ca­tor. We also have an enum that allows us to choose if we want to cal­cu­late the dis­tance in space or pro­ject­ed in a cer­tain plain.

Preparing the Script 

The Script that solves the cal­cu­la­tions calls “Dis­tances” (com­plete Script at the end of the arti­cle), in the fol­low­ing fig­ure, we can see the fields defined in this Script and the Start method.

We have seri­al­ized fields (appear in the inspec­tor) to assign the two spheres from the hier­ar­chy, a TextMesh com­po­nent for the dis­tance indi­ca­tor and the enum that allows us to choose which dis­tance we want to measure.

In the Start method, we find the ref­er­ence of the Line Ren­der­er assigned to the GameOb­ject camera.

In the Update method, we are going to do the cal­cu­la­tions, for this, we define two meth­ods “Cal­cu­late­Dis­tan­ceIn­Space” and “Cal­cu­late­Dis­tanceXY­Plane”, this last one takes into account only the X and Y com­po­nents of the objects as if the objects were pro­ject­ed in the XY plane, this is use­ful when we use the ortho­graph­ic view. In fig­ure 6 we can see these methods.

Arti­cle about “Meth­ods” in programming 

Calculate distance between two objects in space — Vector3

Let’s start by look­ing at how to cal­cu­late the dis­tance between two objects in space, i.e. con­sid­er­ing the three dimen­sions of the scene.

The Cal­cu­late­Dis­tan­ceIn­Space method in Fig­ure 6 takes care of this. As you can see, the “Dis­tance” func­tion of the Vector3 class is used and we use the posi­tions of the objects as para­me­ters, this method will return the dis­tance between the two vectors.

Calculate distance between two objects in the plane — Vector2

If we are work­ing in 2D or if we are inter­est­ed in know­ing the dis­tance between two objects pro­ject­ed on a plane, we can cal­cu­late this dis­tance using only two dimen­sions of the scene.

The Cal­cu­late­Dis­tan­ceInXY­Plane method in Fig­ure 6 takes care of this. As you can see, the Dis­tance method of the Vector2 class is used, two vec­tors are built using only the x and y com­po­nents of the posi­tion of the objects and they are passed as para­me­ters to the Dis­tance method of Vector2.

In the fol­low­ing video, we can see the dif­fer­ence between these two ways of cal­cu­lat­ing dis­tances between objects in Unity.

Conclusion

We have seen how to use the class­es Vector3 and Vector2 to cal­cu­late dis­tances between objects in space and in the plane respectively.

In gen­er­al Uni­ty works in 3D space, there­fore to mea­sure dis­tances in two dimen­sions it is nec­es­sary to project the points in some plane. We have to take into account that there are sev­er­al planes that we can use, in this case, we used the XY plane, but there is also the XZ, the YZ plane and we can even define a plane ori­ent­ed in any direction.

Appendix

Here you can see the com­plete script that cal­cu­lates the dis­tance between two objects in Unity.

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unity get distance between two objects

// Vector3.Distance is the same as (a-b).magnitude

float distance = Vector3.Distance(a.transform.position, b.transform.position);

how to compare distance between 2 objects unity

float distance = Vector3.Distance (object1.transform.position, object2.transform.position);

distance between two objects unity 2d

public GameObject object1;
public GameObject object2;
void Update()
{
  Vector2 Pos1 = object1.transform.position;
  Vector2 Pos2 = object2.transform.position;
  float x1 = Pos1.x, x2 = Pos2.x, y1 = Pos1.y, y2 = Pos2.y;
  // Distance between X coordinates
  float xDif = Mathf.Abs((Mathf.Max(x1,x2) - Mathf.Min(x1,x2));
  // Distance between Y coordinates
  float xDif = Mathf.Abs((Mathf.Max(y1,y2) - Mathf.Min(y1,y2));
  // Pythagorean theorem
  float finalDistance = Mathf.Sqrt(xDif * xDif + yDif * yDif);
  Debug.Log("Distance Between Object1 And Object2 Is " + finalDistance);
}

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