void Mesh::computeFaceGradients(Eigen::MatrixXd& gradients, const Eigen::VectorXd& u) const
{
for (FaceCIter f = faces.begin(); f != faces.end(); f++) {
Eigen::Vector3d gradient;
gradient.setZero();
Eigen::Vector3d normal = f->normal();
normal.normalize();
HalfEdgeCIter he = f->he;
do {
double ui = u(he->next->next->vertex->index);
Eigen::Vector3d ei = he->next->vertex->position - he->vertex->position;
gradient += ui * normal.cross(ei);
he = he->next;
} while (he != f->he);
gradient /= (2.0 * f->area());
gradient.normalize();
gradients.row(f->index) = -gradient;
}
}
void Viewer :: drawPolygons( void )
{
for (FaceCIter f = mesh->faces.begin();
f != mesh->faces.end();
f ++ )
{
bool onBoundary = f->isBoundary();
if( onBoundary )
continue;
glBegin( GL_POLYGON );
if( renderWireframe )
{
Vector3D N = f->normal();
glNormal3dv( &N[0] );
}
HalfEdgeCIter he = f->he;
do
{
if( not renderWireframe )
{
Vector3D N = he->vertex->normal();
glNormal3dv( &N[0] );
}
glVertex3dv( &he->vertex->position[0] );
he = he->next;
}
while( he != f->he );
glEnd();
}
}
void Viewer :: drawVectorField( void )
{
shader.disable();
glPushAttrib( GL_ALL_ATTRIB_BITS );
double h = 0.25*mesh.meanEdgeLength();
glDisable( GL_LIGHTING );
glColor3f( 0., 0., 0. );
glLineWidth( 2.0 );
for( FaceCIter f = mesh.faces.begin();
f != mesh.faces.end();
f ++ )
{
if( f->isBoundary() ) continue;
Vector a = f->barycenter();
Vector b = a + h*f->vector;
Vector n = f->normal();
Vector v = b - a;
Vector v90 = cross(n, v);
Vector p0 = b;
Vector p1 = p0 - 0.2 * v - 0.1 * v90;
Vector p2 = p0 - 0.2 * v + 0.1 * v90;
glBegin( GL_LINES );
glVertex3dv( &a[0] );
glVertex3dv( &b[0] );
glEnd();
glBegin(GL_TRIANGLES);
glVertex3dv( &p0[0] );
glVertex3dv( &p1[0] );
glVertex3dv( &p2[0] );
glEnd();
}
glPopAttrib();
}
void Viewer :: drawPolygons( void )
{
glEnable(GL_COLOR_MATERIAL);
for( FaceCIter f = mesh.faces.begin();
f != mesh.faces.end();
f ++ )
{
if( f->isBoundary() ) continue;
glBegin( GL_POLYGON );
if( renderWireframe )
{
Vector N = f->normal();
glNormal3dv( &N[0] );
}
HalfEdgeCIter he = f->he;
do
{
if( not renderWireframe )
{
Vector N = he->vertex->normal();
glNormal3dv( &N[0] );
}
double alpha = he->vertex->distance / maxDistance;
glColor4f( alpha, alpha, alpha, 1. );
glVertex3dv( &he->vertex->position[0] );
he = he->next;
}
while( he != f->he );
glEnd();
}
glDisable(GL_COLOR_MATERIAL);
}
