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  Normals get messed up  (Read 2835 times)
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Offline RobinB

JGO Ninja


Medals: 44
Projects: 1
Exp: 3 years


Spacegame in progress


« Posted 2013-06-19 19:30:04 »

Im having a problem with my normals since im trying to generate and render some complexer models than flat terrain.
The model is rendered using code, and the normals are calculated for each vertex from the neightbouring indices.

Getting normals from indices
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    public Vector3f getNormal(){
        Vector3f normal = crossProduct(v1.getPosition(), v2.getPosition(), v3.getPosition());
        if(normal.length() == 0){ normal = new Vector3f(1,1,1); }
       
        normal.normalise();
        return normal;
    }
   
       
    private Vector3f crossProduct(Vector3f v1, Vector3f v2, Vector3f v3)
    {
        Vector3f e1, e2;
        e1 = new Vector3f(v1.x-v2.x, v1.y-v2.y, v1.z-v2.z);
        e2 = new Vector3f(v2.x-v3.x, v2.y-v3.y, v2.z-v3.z);

        return new Vector3f(e1.y*e2.z-e1.z*e2.z, e1.z*e2.x-e1.x*e2.z, e1.x*e2.y-e1.y*e2.x);
    }


Getting vertex normals:
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    protected void calcNormals(){
        normal = new Vector3f(0,0,0);
       
        for(TriangleIndice f : faces){
            Vector3f.add(normal, f.getNormal(), normal);
        }
     
        normal.normalise();
    }


The error im having:


The error happens mostly at the X sides.
Im using a icosphere for the head, so the error does not lay at any vertex seams or something.



Can anyone help me please, im really breaking my head over it.
Thanks in advance Smiley
Offline RobinB

JGO Ninja


Medals: 44
Projects: 1
Exp: 3 years


Spacegame in progress


« Reply #1 - Posted 2013-06-19 22:20:44 »

Finally found out why the normals are so strange with my implementations.
The crossProduct code i used, was wrong.

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    private Vector3f crossProduct(Vector3f v1, Vector3f v2, Vector3f v3)
    {
        Vector3f e1, e2;
        e1 = new Vector3f(v1.x-v2.x, v1.y-v2.y, v1.z-v2.z);
        e2 = new Vector3f(v1.x-v3.x, v1.y-v3.y, v1.z-v3.z);

        return Vector3f.cross(e1, e2, null);
    }
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