Get face normal and get its local Euler Angles?

Question

I have a simple script w$$anonymous$$ch checks using raycast and gets mesh face normals and what I want to do is to get it's local rotation so i can make my object rotated alike... is that possible? Here's the code I'm using to get face normals:

 private var Target : Transform;
 var Hit : RaycastHit;
 var layerMask = 1<<8;
 private var faceNormalZ : float = 0;
 private var faceNormalX : float = 0;
 
 function Start () {
     Target = GameObject.FindWithTag("Player").transform;
 }
 
 function Update (){
     transform.position = Target.position;
     transform.localEulerAngles.y = Target.localEulerAngles.y;
     transform.rotation.x = faceNormalX;
     transform.rotation.z = faceNormalZ;
     
     if (Physics.Raycast(transform.position, Vector3.down, Hit, 2, layerMask)){
     var meshCollider = Hit.collider as MeshCollider;}
         if (meshCollider == null || meshCollider.sharedMesh == null)
         return;
             
         var mesh : Mesh = meshCollider.sharedMesh;
         var vertices = mesh.vertices;
         var triangles = mesh.triangles;
         var normals = mesh.normals;
     
         P1 = vertices[triangles[Hit.triangleIndex * 3]];
         P2 = vertices[triangles[Hit.triangleIndex * 3 + 1]];
         P3 = vertices[triangles[Hit.triangleIndex * 3 + 2]];
             center = ((P1 + P2 + P3) / 3);
 
         P1 = normals[triangles[Hit.triangleIndex * 3]];
         P2 = normals[triangles[Hit.triangleIndex * 3 + 1]];
         P3 = normals[triangles[Hit.triangleIndex * 3 + 2]];
             faceNormal = ((P1 + P2 + P3) / 3);
             faceNormalZ = faceNormal.z;
             faceNormalX = -faceNormal.x;
 }

Answer 1

Best Answer

Answer by Berenger · Jun 06, 2012 at 03:01 PM

(Theory) You can't know the rotation of a vector, because it doesn't make sense. It need to be relative to somet$$anonymous$$ng. You might need confirmation of someone good in math, but I t$$anonymous$$nk there is an infinity of rotation from a vector to another, so I t$$anonymous$$nk you need 2 relative vectors.

Anyway, you probably want to use Quaternion.LookRotation.

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Answer 2

Answer by Mortoc · Jun 06, 2012 at 02:55 PM

You don't have to dig in to the mesh for t$$anonymous$$s, you can just use:

 someObject.transform.position = Hit.position;
 someObject.transform.up = Hit.normal;

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zero3growlithe · Jun 06, 2012 at 05:38 PM 1

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well, not really as it won't give me "face" normal but Hit.point normal so if my raycast will hit another object under an angle then my object will rotate to that angle and not to face normal :/

Mortoc · Jun 06, 2012 at 05:45 PM 2

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Ah right, I misread the problem. You can still calculate the face normal by:

 Vector3.Cross(p2 - p1, p2 - p3).normalized

and then set someObject.transform.up to the result of that

Answer 3

Answer by DHARMAKAYA · Nov 08, 2016 at 03:31 PM

Stop capping the first letter of vars!!!!! THAT IS THE PROBLEM HERE!!!!

(shaking fist in air)

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zero3growlithe · Nov 08, 2016 at 05:29 PM 1

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Haha, this question was asked 4 years ago, I've improved my C# coding skills by just "a lot" since then, dw :))

Get face normal and get its local Euler Angles?

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