Point operator()(MESH& m, NODE n, double t) {
(void) t;
Point pressure_force = Point(0.0, 0.0, 0.0);
for(auto it=m.adj_triangle_begin(n.uid()); it != m.adj_triangle_end(n.uid()); ++ it) {
auto tri = (*it);
Point normal = get_normal_surface(tri);
double area = tri.area();
pressure_force += normal * area * pressure;
}
return pressure_force;
}
Point operator() (MESH& m, NODE n, double t){
Point node_velocity = n.value().velocity;
Point node_normal(0.0, 0.0, 0.0);
for (auto it = m.adj_triangle_begin(n.uid()); it != m.adj_triangle_end(n.uid()); ++it){
auto tri = (*it);
// approximate node normal vector by the sum of normal vectors of its neighboring faces
node_normal += get_normal_surface(tri);
}
// calculte wind force
Point force = wind_const * dot(wind_velocity_ - node_velocity, node_normal) * node_normal;
(void) t;
return force;
}
Point post_process(MESH& m, FORCE force, CONSTRAINT& c, double t, double dt, uint water_nodes) {
static double ball_bottom = std::numeric_limits<double>::max();
double water_dis = std::numeric_limits<double>::max();
double dh = 0;
static double submerged_height = 0;
Point bottom_loc;
Point water_loc;
for (auto n_it = m.node_begin(); n_it != m.node_end(); ++n_it) {
// handles the shallow water
if ((*n_it).index() < water_nodes) {
double sum_area = 0;
QVar value = QVar(0,0,0);
for (auto tri_it = m.adj_triangle_begin((*n_it).uid()); tri_it != m.adj_triangle_end((*n_it).uid()); ++tri_it) {
value += (*tri_it).value().q_bar * (*tri_it).area();
sum_area += (*tri_it).area();
}
(*n_it).value().q = value * 1.0/(sum_area);
}
// handles the ball
else {
(*n_it).set_position((*n_it).position() + (*n_it).value().velocity*dt);
dh = (*n_it).value().q.h - (*n_it).position().z;
(*n_it).value().q.h = (*n_it).position().z;
(*n_it).value().velocity += force(m,(*n_it),t)*dt/(*n_it).value().mass;
if ((*n_it).value().q.h < ball_bottom) {
ball_bottom = (*n_it).position().z;
bottom_loc = (*n_it).position();
}
}
}
// find the water node closest to the bottom of the ball
for (auto n_it = m.node_begin(); (*n_it).index() != water_nodes; ++n_it) {
if (norm(Point((*n_it).position().x,(*n_it).position().y,0)-Point(bottom_loc.x,bottom_loc.y,0)) < water_dis){
water_dis = norm(Point((*n_it).position().x,(*n_it).position().y,0)-Point(bottom_loc.x,bottom_loc.y,0));
water_loc = Point((*n_it).position().x,(*n_it).position().y,(*n_it).value().q.h);
}
}
// apply contraints of neccessary
c(m,ball_bottom);
// determines if the ball fell below shallow water and updates height submerged
if (bottom_loc.z < water_loc.z)
submerged_height += dh;
return Point(bottom_loc.x, bottom_loc.y, submerged_height);
}