camera.ScreenPointToRay Seems to not work...

Unity Engine
1

I have a script that gets 4 rays based off of the Mouse down point and the mouse up point on the screen.
(Box group selection)

I use the Command camera.ScreenPointToRay to generate the first 4 verticies of the box, and use the directions of the ray to determine the last 4 points of the box.

For some reason The box’s vertexes are inaccurate in when compared to the camera’s position.

However, It DOES work when the camera is at position 0,0,0, and 0,0,0 rotation.

For those that wish to test it themselves you just need a blank Project scene and attach this script to the main camera. And one prefab with only a game object. Must assign it to the box field on the script on the camera.

var box : GameObject;
private var CrnFirst : Vector3;
private var Crnend : Vector3;
private var Hal : GameObject;
function Update ()
{

if (Input.GetMouseButtonDown(0))
	{
	CrnFirst = Input.mousePosition;
	}
if (Input.GetMouseButtonUp(0))
	{
	Crnend = Input.mousePosition;
	//print("Spot 1: " + CrnFirst + "Spot 2: " + Crnend);
	//print(camera.ScreenPointToRay(CrnFirst));
	SelectionCube();
	}

}

function SelectionCube()
{
	Hal = Instantiate (box,transform.position,transform.rotation);

	Hal.AddComponent("MeshFilter");
	Hal.AddComponent("MeshRenderer");
	var mesh : Mesh = Hal.GetComponent(MeshFilter).mesh;
	var rays : Ray[];
	rays = new Ray[4];
	rays[0] = camera.ScreenPointToRay(CrnFirst);
	rays[1] = camera.ScreenPointToRay(Vector3(Crnend.x, CrnFirst.y));
	rays[2] = camera.ScreenPointToRay(Crnend);
	rays[3] = camera.ScreenPointToRay(Vector3( CrnFirst.x,Crnend.y));
	print(rays[0]);
	var size = 1; 
	 var vertexList = [
		  rays[3].origin,
		  rays[0].origin,
		  (rays[0].origin+(rays[0].direction*500)),
		  (rays[3].origin+(rays[3].direction*500)),
		  (rays[1].origin+(rays[2].direction*500)),
		  (rays[1].origin+(rays[1].direction*500)),
		  rays[1].origin,
		  rays[2].origin
	   ]; 
	
	mesh.vertices = vertexList;

	var faceList = [
		 2,1,0,
		 3,2,0,
		 //0, 1, 2, //   1: face arrière
		  //0, 2, 3,
		  
		//  3, 2, 5, //   2: face droite
		  //3, 5, 4,
		  5,2,3,
		  4,5,3,
		  
		  //5, 2, 1, //   3: face dessue
		  //5, 1, 6,
		  1,2,5,
		  6,1,5,
		  
		  //3, 4, 7, //   4: face dessous
		  //3, 7, 0,
		  7,4,3,
		  0,7,3,
		  
		  //0, 7, 6, //   5: face gauche
		  //0, 6, 1,
		  6,7,0,
		  1,6,0,
		  
		  //4, 5, 6, //   6: face avant
		  //4, 6, 7
		  6,5,4,
		  7,6,4
		  
	   ]; 
	mesh.vertices = vertexList;
	mesh.triangles = faceList;
	mesh.RecalculateNormals();

	}
2

Try using Ray.GetPoint(distance : float) instead of

        (rays[0].origin+(rays[0].direction*500)), 
        (rays[3].origin+(rays[3].direction*500)), 
        (rays[1].origin+(rays[2].direction*500)), 
        (rays[1].origin+(rays[1].direction*500)),
3

Hmm I’ll definitely give that a shot, but I think my problem is the origin is incorrect.

As the first 4 verticies which should show up right in front of the camera, end up 10-20 units away from the camera when it is not at 0,0,0.

4

If something works only when an object is at the coordinate origin and neutral rotation, it usually means there is some confusion between local and world coordinates. In this case, you are setting the vertices to the (modified) values returned by ScreenPointToRay, which are in world coordinates, but vertices are almost always supposed to be local values. Try using transform.InverseTransformPoint to convert world coordinates into points local to the transform.

5

Haha! That was the problem, thank you so much! Works like a charm now.

Updated code:

var box : GameObject;
private var CrnFirst : Vector3;
private var Crnend : Vector3;
private var Hal : GameObject;
function Update ()
{

if (Input.GetMouseButtonDown(0))
	{
	CrnFirst = Input.mousePosition;
	}
if (Input.GetMouseButtonUp(0))
	{
	Crnend = Input.mousePosition;
	//print("Spot 1: " + CrnFirst + "Spot 2: " + Crnend);
	//print(camera.ScreenPointToRay(CrnFirst));
	SelectionCube();
	}

}

function SelectionCube()
{
	Hal = Instantiate (box,transform.position,transform.rotation);

	Hal.AddComponent("MeshFilter");
	Hal.AddComponent("MeshRenderer");
	var mesh : Mesh = Hal.GetComponent(MeshFilter).mesh;
	var rays : Ray[];
	rays = new Ray[4];
	rays[0] = camera.ScreenPointToRay(CrnFirst);
	rays[1] = camera.ScreenPointToRay(Vector3(Crnend.x, CrnFirst.y));
	rays[2] = camera.ScreenPointToRay(Crnend);
	rays[3] = camera.ScreenPointToRay(Vector3( CrnFirst.x,Crnend.y));
	print(rays[0]);
	var size = 1; 
	 var vertexList = [
		  Hal.transform.InverseTransformPoint(rays[3].origin),
		  Hal.transform.InverseTransformPoint(rays[0].origin),
		  Hal.transform.InverseTransformPoint((rays[0].origin+(rays[0].direction*500))),
		  Hal.transform.InverseTransformPoint((rays[3].origin+(rays[3].direction*500))),
		  Hal.transform.InverseTransformPoint((rays[1].origin+(rays[2].direction*500))),
		  Hal.transform.InverseTransformPoint((rays[1].origin+(rays[1].direction*500))),
		  Hal.transform.InverseTransformPoint(rays[1].origin),
		  Hal.transform.InverseTransformPoint(rays[2].origin)
	   ]; 
	
	mesh.vertices = vertexList;

	var faceList = [
		 2,1,0,
		 3,2,0,
		 //0, 1, 2, //   1: face arrière
		  //0, 2, 3,
		  
		//  3, 2, 5, //   2: face droite
		  //3, 5, 4,
		  5,2,3,
		  4,5,3,
		  
		  //5, 2, 1, //   3: face dessue
		  //5, 1, 6,
		  1,2,5,
		  6,1,5,
		  
		  //3, 4, 7, //   4: face dessous
		  //3, 7, 0,
		  7,4,3,
		  0,7,3,
		  
		  //0, 7, 6, //   5: face gauche
		  //0, 6, 1,
		  6,7,0,
		  1,6,0,
		  
		  //4, 5, 6, //   6: face avant
		  //4, 6, 7
		  6,5,4,
		  7,6,4
		  
	   ]; 
	mesh.vertices = vertexList;
	mesh.triangles = faceList;
	mesh.RecalculateNormals();

	}