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perf: add fast path for extracting meshes w/o simplification #35

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perf: add fast path for extracting meshes w/o simplification #35

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63 changes: 62 additions & 1 deletion cMesher.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
#include <zi/mesh/marching_cubes.hpp>
#include <zi/mesh/int_mesh.hpp>
#include <zi/mesh/quadratic_simplifier.hpp>
#include <zi/bits/unordered_map.hpp>
#include <zi/vl/vec.hpp>

struct MeshObject {
Expand Down Expand Up @@ -62,7 +63,12 @@ class CMesher {
return empty_obj;
}

std::vector< zi::vl::vec< PositionType, 3> > triangles = marchingcubes_.get_triangles(segid);
std::vector< zi::vl::vec< PositionType, 3> > triangles = std::move(marchingcubes_.get_triangles(segid));

// faster
if (simplification_factor == 0 && !generate_normals) {
return trianges2mesh(triangles);
}

return simplify(
triangles,
Expand All @@ -72,6 +78,61 @@ class CMesher {
);
}

// This is only for converting triangles
// into a vertex and face triangle soup object
// with no simplification or normal calculation.
MeshObject trianges2mesh(
const std::vector< zi::vl::vec< PositionType, 3> >& triangles
) {
MeshObject obj;

uint32_t idx = 0;
zi::unordered_map<PositionType, uint32_t> pts;
pts.reserve(3 * triangles.size());


for (auto &tri : triangles) {
if (!pts.count(tri.at(0))) {
pts.insert(std::make_pair(tri.at(0), idx++));
}
if (!pts.count(tri.at(1))) {
pts.insert(std::make_pair(tri.at(1), idx++));
}
if (!pts.count(tri.at(2))) {
pts.insert(std::make_pair(tri.at(2), idx++));
}
}

zi::unordered_map<uint32_t, PositionType> ipts;
for (auto it : pts) {
ipts[it.second] = it.first;
}

obj.points.reserve(pts.size());
obj.faces.reserve(3 * triangles.size());

for (uint32_t i = 0; i < idx; i++) {
PositionType vert = ipts[i];
obj.points.push_back(
zi::mesh::marching_cubes<PositionType, LabelType>::template unpack_z<SimplifierType>(vert)
);
obj.points.push_back(
zi::mesh::marching_cubes<PositionType, LabelType>::template unpack_y<SimplifierType>(vert)
);
obj.points.push_back(
zi::mesh::marching_cubes<PositionType, LabelType>::template unpack_x<SimplifierType>(vert)
);
}

for (auto &tri : triangles) {
obj.faces.push_back(pts[tri.at(0)]);
obj.faces.push_back(pts[tri.at(2)]);
obj.faces.push_back(pts[tri.at(1)]);
}

return obj;
}

MeshObject simplify(
const std::vector< zi::vl::vec< PositionType, 3> >& triangles,
bool generate_normals,
Expand Down