void Poly::SortVerticesCW ( )
{
//
// Calculate center of polygon
//
Vector3 center;
for ( int i = 0; i < GetNumberOfVertices ( ); i++ )
{
center = center + verts[ i ].p;
}
center = center / GetNumberOfVertices ( );
//
// Sort vertices
//
for ( i = 0; i < GetNumberOfVertices ( ) - 2; i++ )
{
Vector3 a;
Plane p;
double SmallestAngle = -1;
int Smallest = -1;
a = verts[ i ].p - center;
a.Normalize ( );
p.PointsToPlane ( verts[ i ].p, center, center + plane.n );
for ( int j = i + 1; j < GetNumberOfVertices ( ); j++ )
{
if ( p.ClassifyPoint ( verts[ j ].p ) != Plane::eCP::BACK )
{
Vector3 b;
double Angle;
b = verts[ j ].p - center;
b.Normalize ( );
Angle = a.Dot ( b );
if ( Angle > SmallestAngle )
{
SmallestAngle = Angle;
Smallest = j;
}
}
}
if ( Smallest == -1 )
{
cout << "Error: Degenerate polygon!" << endl;
abort ( );
}
Vertex t = verts[ Smallest ];
verts[ Smallest ] = verts[ i + 1 ];
verts[ i + 1 ] = t;
}
//
// Check if vertex order needs to be reversed for back-facing polygon
//
Plane oldPlane = plane;
CalculatePlane ( );
if ( plane.n.Dot ( oldPlane.n ) < 0 )
{
int j = GetNumberOfVertices ( );
for ( int i = 0; i < j / 2; i++ )
{
Vertex v = verts[ i ];
verts[ i ] = verts[ j - i - 1 ];
verts[ j - i - 1 ] = v;
}
}
}
