void TrackMapper::set_factor (const Streamline<>& tck, SetVoxelExtras& out) const
{
factors.clear();
factors.reserve (tck.size());
load_factors (tck);
gaussian_smooth_factors (tck);
out.factor = 1.0;
}
bool Downsampler::operator() (const Streamline<>& in, Streamline<>& out) const
{
out.clear();
out.index = in.index;
out.weight = in.weight;
if (ratio <= 1 || in.empty())
return false;
if (in.size() == 1)
return true;
out.push_back (in.front());
const size_t midpoint = in.size()/2;
size_t index = (((midpoint - 1) % ratio) + 1);
while (index < in.size() - 1) {
out.push_back (in[index]);
index += ratio;
}
out.push_back (in.back());
return true;
}
bool FixedNumPoints::operator() (const Streamline<>& in, Streamline<>& out) const
{
// Perform an explicit calculation of streamline length
// From this, derive the spline position of each sample
assert (in.size() > 1);
out.clear();
out.index = in.index;
out.weight = in.weight;
value_type length = 0.0;
vector<value_type> steps;
for (size_t i = 1; i != in.size(); ++i) {
const value_type dist = (in[i] - in[i-1]).norm();
length += dist;
steps.push_back (dist);
}
steps.push_back (value_type(0));
Math::Hermite<value_type> interp (hermite_tension);
Streamline<> temp (in);
const size_t s = temp.size();
temp.insert (temp.begin(), temp[0] + (temp[0] - temp[ 1 ]));
temp.push_back ( temp[s] + (temp[s] - temp[s-1]));
value_type cumulative_length = value_type(0);
size_t input_index = 0;
for (size_t output_index = 0; output_index != num_points; ++output_index) {
const value_type target_length = length * output_index / value_type(num_points-1);
while (input_index < s && (cumulative_length + steps[input_index] < target_length))
cumulative_length += steps[input_index++];
if (input_index == s) {
out.push_back (temp[s]);
break;
}
const value_type mu = (target_length - cumulative_length) / steps[input_index];
interp.set (mu);
out.push_back (interp.value (temp[input_index], temp[input_index+1], temp[input_index+2], temp[input_index+3]));
}
return true;
}
