Tangent calculation

[capedica]

Hi,
sorry for problems that i have with shader, this is one of these: i’m using this code to calculate tangent from vertex,normal and texture coordinates :

Code from Terathon
but the result is this (i’m using a classic normal map shader):

The code that i’m using is this:

void VRMeshLoader::BuildTangent(VRNewMesh *mesh)
{
mesh->m_tangent = new GLfloat[mesh->m_vertex_count*4];

 for(int i=0;i<mesh->m_vertex_count;i++)
	{
		mesh->m_tangent[i*4]=0.0;
		mesh->m_tangent[i*4+1]=0.0;
		mesh->m_tangent[i*4+2]=0.0;
		mesh->m_tangent[i*4+3]=0.0;
	}


    GLfloat *tan1 = new GLfloat[mesh->m_vertex_count*3 * 2];
	GLfloat *tan2 = tan1 +mesh->m_vertex_count*3;
 
	for(int i=0;i<mesh->m_vertex_count*3*2;i++)
	   {
	    tan1[i] = 0.0;
	   }
		

	for (long a = 0; a < mesh->m_tri_count; a++)
	{
		
		
	    long i1 = mesh->m_tri_index[a*3];
		long i2 = mesh->m_tri_index[a*3+1];
		long i3 = mesh->m_tri_index[a*3+2];

		
		 GLfloat* v1 = &mesh->m_vertex[i1*3];
		 GLfloat* v2 = &mesh->m_vertex[i2*3];
		 GLfloat* v3 = &mesh->m_vertex[i3*3];
		
		
		 GLfloat* w1 = &mesh->m_tex_coord[2*mesh->m_tri_texindex[a*3]];
		 GLfloat* w2 = &mesh->m_tex_coord[2*mesh->m_tri_texindex[a*3+1]];
		 GLfloat* w3 = &mesh->m_tex_coord[2*mesh->m_tri_texindex[a*3+2]];
    	

		float x1 = v2[0] - v1[0];
		float x2 = v3[0] - v1[0];
		float y1 = v2[1] - v1[1];
		float y2 = v3[1] - v1[1];
		float z1 = v2[2] - v1[2];
		float z2 = v3[2] - v1[2];
		
		float s1 = (w2[0] - w1[0]);
		float s2 = (w3[0] - w1[0]);
		float t1 = (w2[1] - w1[1]);
		float t2 = (w3[1] - w1[1]);
		

		float r = 1.0f / (s1 * t2 - s2 * t1);
		if (fabs(r)>10e6)  
			 r=0.0;          //
		float sdir[3] = {(t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r,
				(t2 * z1 - t1 * z2) * r};
		float tdir[3] = {(s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r,
				(s1 * z2 - s2 * z1) * r};

		
		
		tan1[i1*3]   += sdir[0];
		tan1[i1*3+1] += sdir[1];
		tan1[i1*3+2] += sdir[2];
		
		tan1[i2*3]   += sdir[0];
		tan1[i2*3+1] += sdir[1];
		tan1[i2*3+2] += sdir[2];
		
		tan1[i3*3]   += sdir[0];
		tan1[i3*3+1] += sdir[1];
		tan1[i3*3+2] += sdir[2];
		
		
		tan2[i1*3]   += tdir[0];
		tan2[i1*3+1] += tdir[1];
		tan2[i1*3+2] += tdir[2];
		
		tan2[i2*3]   += tdir[0];
		tan2[i2*3+1] += tdir[1];
		tan2[i2*3+2] += tdir[2];
		
		tan2[i3*3]   += tdir[0];
		tan2[i3*3+1] += tdir[1];
		tan2[i3*3+2] += tdir[2];
		
	
	}

    long count = mesh->m_vertex_count;
	GLfloat* n;
	GLfloat* t;

	for (long a = 0; a < count; a++)
	{
		
	     n = &mesh->m_vertex_normals[a*3];
		 t = &tan1[a*3];
         float calctemp;
		 float temp[3];

		 // Gram-Schmidt orthogonalize
		 // Calcolo (t-n*(n*t))
         calctemp = (n[0]*t[0]+n[1]*t[1]+n[2]*t[2]);
		 mesh->m_tangent[a*4]   = t[0] - calctemp*n[0];
         mesh->m_tangent[a*4+1] = t[1] - calctemp*n[1];
         mesh->m_tangent[a*4+2] = t[2] - calctemp*n[2];
        
		 
        float d = sqrtf(mesh->m_tangent[a*4]*mesh->m_tangent[a*4]+mesh->m_tangent[a*4+1]*mesh->m_tangent[a*4+1]+mesh->m_tangent[a*4+2]*mesh->m_tangent[a*4+2]);

		if (d!=0.0)
		{
			mesh->m_tangent[a*4] /= d; 
			mesh->m_tangent[a*4+1] /= d; 
			mesh->m_tangent[a*4+2] /= d;
		}

		 // Calculate handedness
		 //  n%t
        temp[0] = n[1]*t[2]-n[2]*t[1];
        temp[1] = n[2]*t[0]-n[0]*t[2];
        temp[2] = n[0]*t[1]-n[1]*t[0];

		

		mesh->m_tangent[a*4+3] = (temp[0]*tan2[a*3]+temp[1]*tan2[a*3+1]+temp[2]*tan2[a*3+2] < 0.0f) ? 1.0f : -1.0f;
	
		

	}
	
	delete[] tan1;

    
	mesh->m_bitangent = new GLfloat[mesh->m_vertex_count*3];

 for(int i=0;i<mesh->m_vertex_count;i++)
	{
		mesh->m_bitangent[i*3]=0.0;
		mesh->m_bitangent[i*3+1]=0.0;
		mesh->m_bitangent[i*3+2]=0.0;
	}

for(int i=0;i<mesh->m_vertex_count;i++)
	{
	mesh->m_bitangent[i*3] = (mesh->m_vertex_normals[i*3+1]*mesh->m_tangent[i*4+2] - mesh->m_vertex_normals[i*3+2]*mesh->m_tangent[i*4+1])*mesh->m_tangent[i*4+3]; 
    mesh->m_bitangent[i*3+1] = (mesh->m_vertex_normals[i*3+2]*mesh->m_tangent[i*4] - mesh->m_vertex_normals[i*3]*mesh->m_tangent[i*4+2])*mesh->m_tangent[i*4+3];
    mesh->m_bitangent[i*3+2] = (mesh->m_vertex_normals[i*3]*mesh->m_tangent[i*4+1] - mesh->m_vertex_normals[i*3+1]*mesh->m_tangent[i*4])*mesh->m_tangent[i*4+3];
	}

}

  

Do you ever had a visual problem similiar to this? and which could be possible causes (all that came in your mine)?
is it possible a problem with smoothing groups?
Thank you very much