void VectCreate(p3d_type *p_start, p3d_type *p_end, p3d_type *p_vector )
{
p_vector->x = p_end->x - p_start->x;
p_vector->y = p_end->y - p_start->y;
p_vector->z = p_end->z - p_start->z;
VectNormalize(p_vector);
}
void Calc3DSNormals(obj3ds_type *p_object)
{
int i;
p3d_type l_vect1,l_vect2,l_vect3,l_vect_b1,l_vect_b2,l_normal; //Some local vectors
int l_connections_qty[MAX_VERTICES]; //Number of poligons around each vertex
// Resetting vertices' normals...
for( i=0; i<p_object->vertices_qty; ++i )
{
p_object->normal[i].x = 0.0f;
p_object->normal[i].y = 0.0f;
p_object->normal[i].z = 0.0f;
l_connections_qty[i]=0;
}
for (i=0; i<p_object->polygons_qty; i++)
{
l_vect1.x = p_object->vertex[p_object->polygon[i].a].x;
l_vect1.y = p_object->vertex[p_object->polygon[i].a].y;
l_vect1.z = p_object->vertex[p_object->polygon[i].a].z;
l_vect2.x = p_object->vertex[p_object->polygon[i].b].x;
l_vect2.y = p_object->vertex[p_object->polygon[i].b].y;
l_vect2.z = p_object->vertex[p_object->polygon[i].b].z;
l_vect3.x = p_object->vertex[p_object->polygon[i].c].x;
l_vect3.y = p_object->vertex[p_object->polygon[i].c].y;
l_vect3.z = p_object->vertex[p_object->polygon[i].c].z;
// Polygon normal calculation
VectCreate( &l_vect1, &l_vect2, &l_vect_b1 ); // Vector from the first vertex to the second one
VectCreate ( &l_vect1, &l_vect3, &l_vect_b2 ); // Vector from the first vertex to the third one
VectDotProduct( &l_vect_b1, &l_vect_b2, &l_normal ); // Dot product between the two vectors
VectNormalize( &l_normal ); //Normalizing the resultant we obtain the polygon normal
l_connections_qty[p_object->polygon[i].a]+=1; // For each vertex shared by this polygon we increase the number of connections
l_connections_qty[p_object->polygon[i].b]+=1;
l_connections_qty[p_object->polygon[i].c]+=1;
p_object->normal[p_object->polygon[i].a].x+=l_normal.x; // For each vertex shared by this polygon we add the polygon normal
p_object->normal[p_object->polygon[i].a].y+=l_normal.y;
p_object->normal[p_object->polygon[i].a].z+=l_normal.z;
p_object->normal[p_object->polygon[i].b].x+=l_normal.x;
p_object->normal[p_object->polygon[i].b].y+=l_normal.y;
p_object->normal[p_object->polygon[i].b].z+=l_normal.z;
p_object->normal[p_object->polygon[i].c].x+=l_normal.x;
p_object->normal[p_object->polygon[i].c].y+=l_normal.y;
p_object->normal[p_object->polygon[i].c].z+=l_normal.z;
}
for (i=0; i<p_object->vertices_qty; i++)
{
if (l_connections_qty[i]>0)
{
p_object->normal[i].x /= l_connections_qty[i]; // Let's now average the polygons' normals to obtain the vertex normal!
p_object->normal[i].y /= l_connections_qty[i];
p_object->normal[i].z /= l_connections_qty[i];
}
}
}
vertex polygon::VectCreate( vertex p_start, vertex p_end )
{
vertex v;
v.wx = p_end.wx - p_start.wx;
v.wy = p_end.wy - p_start.wy;
v.wz = p_end.wz - p_start.wz;
VectNormalize( v );
return v;
}
//funktion zum berechnen der normalen
void polygon::calculateNormal( vertex p_vector1, vertex p_vector2 )
{
//anwendung des Kreuzproduktes:
this->normal.wx = (p_vector1.wy * p_vector2.wz) - (p_vector1.wz * p_vector2.wy);
this->normal.wy = (p_vector1.wz * p_vector2.wx) - (p_vector1.wx * p_vector2.wz);
this->normal.wz = (p_vector1.wx * p_vector2.wy) - (p_vector1.wy * p_vector2.wx);
VectNormalize( this->normal );
vertex point_light( 10.0f, 0.0f, -1.0f);
vertex point_zero( 0,0,0 );
vertex vector_light = VectCreate( point_zero, point_light );
this->helligkeit = VectScalarProduct( this->normal, vector_light );
}
