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// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#include "draco/mesh/mesh_cleanup.h"
#include <unordered_set>
#include "draco/core/hash_utils.h"
namespace draco {
Status MeshCleanup::Cleanup(Mesh *mesh, const MeshCleanupOptions &options) {
if (!options.remove_degenerated_faces && !options.remove_unused_attributes &&
!options.remove_duplicate_faces && !options.make_geometry_manifold) {
return OkStatus(); // Nothing to cleanup.
}
const PointAttribute *const pos_att =
mesh->GetNamedAttribute(GeometryAttribute::POSITION);
if (pos_att == nullptr) {
return Status(Status::DRACO_ERROR, "Missing position attribute.");
}
if (options.remove_degenerated_faces) {
RemoveDegeneratedFaces(mesh);
}
if (options.remove_duplicate_faces) {
RemoveDuplicateFaces(mesh);
}
if (options.remove_unused_attributes) {
RemoveUnusedAttributes(mesh);
}
return OkStatus();
}
void MeshCleanup::RemoveDegeneratedFaces(Mesh *mesh) {
const PointAttribute *const pos_att =
mesh->GetNamedAttribute(GeometryAttribute::POSITION);
FaceIndex::ValueType num_degenerated_faces = 0;
// Array for storing position indices on a face.
std::array<AttributeValueIndex, 3> pos_indices;
for (FaceIndex f(0); f < mesh->num_faces(); ++f) {
const Mesh::Face &face = mesh->face(f);
for (int p = 0; p < 3; ++p) {
pos_indices[p] = pos_att->mapped_index(face[p]);
}
if (pos_indices[0] == pos_indices[1] || pos_indices[0] == pos_indices[2] ||
pos_indices[1] == pos_indices[2]) {
++num_degenerated_faces;
} else if (num_degenerated_faces > 0) {
// Copy the face to its new location.
mesh->SetFace(f - num_degenerated_faces, face);
}
}
if (num_degenerated_faces > 0) {
mesh->SetNumFaces(mesh->num_faces() - num_degenerated_faces);
}
}
void MeshCleanup::RemoveDuplicateFaces(Mesh *mesh) {
const PointAttribute *const pos_att =
mesh->GetNamedAttribute(GeometryAttribute::POSITION);
typedef std::array<AttributeValueIndex::ValueType, 3> PosTriplet;
PosTriplet pos_indices;
std::unordered_set<PosTriplet, HashArray<PosTriplet>> is_face_used;
uint32_t num_duplicate_faces = 0;
for (FaceIndex fi(0); fi < mesh->num_faces(); ++fi) {
const auto f = mesh->face(fi);
for (int c = 0; c < 3; ++c) {
pos_indices[c] = pos_att->mapped_index(f[c]).value();
}
// Shift the position indices until the smallest index is the first one.
while (pos_indices[0] > pos_indices[1] || pos_indices[0] > pos_indices[2]) {
// Shift to the left.
std::swap(pos_indices[0], pos_indices[1]);
std::swap(pos_indices[1], pos_indices[2]);
}
// Check if have encountered the same position triplet on a different face.
if (is_face_used.find(pos_indices) != is_face_used.end()) {
// Duplicate face. Ignore it.
num_duplicate_faces++;
} else {
// Insert new face to the set.
is_face_used.insert(pos_indices);
if (num_duplicate_faces > 0) {
// Copy the face to its new location.
mesh->SetFace(fi - num_duplicate_faces, f);
}
}
}
if (num_duplicate_faces > 0) {
mesh->SetNumFaces(mesh->num_faces() - num_duplicate_faces);
}
}
void MeshCleanup::RemoveUnusedAttributes(Mesh *mesh) {
// Array that is going to store whether a corresponding point is used.
std::vector<bool> is_point_used;
PointIndex::ValueType num_new_points = 0;
is_point_used.resize(mesh->num_points(), false);
for (FaceIndex f(0); f < mesh->num_faces(); ++f) {
const Mesh::Face &face = mesh->face(f);
for (int p = 0; p < 3; ++p) {
if (!is_point_used[face[p].value()]) {
is_point_used[face[p].value()] = true;
++num_new_points;
}
}
}
bool points_changed = false;
const PointIndex::ValueType num_original_points = mesh->num_points();
// Map from old points to the new ones.
IndexTypeVector<PointIndex, PointIndex> point_map(num_original_points);
if (num_new_points < static_cast<int>(mesh->num_points())) {
// Some of the points were removed. We need to remap the old points to the
// new ones.
num_new_points = 0;
for (PointIndex i(0); i < num_original_points; ++i) {
if (is_point_used[i.value()]) {
point_map[i] = num_new_points++;
} else {
point_map[i] = kInvalidPointIndex;
}
}
// Go over faces and update their points.
for (FaceIndex f(0); f < mesh->num_faces(); ++f) {
Mesh::Face face = mesh->face(f);
for (int p = 0; p < 3; ++p) {
face[p] = point_map[face[p]];
}
mesh->SetFace(f, face);
}
// Set the new number of points.
mesh->set_num_points(num_new_points);
points_changed = true;
} else {
// No points were removed. Initialize identity map between the old and new
// points.
for (PointIndex i(0); i < num_original_points; ++i) {
point_map[i] = i;
}
}
// Update index mapping for attributes.
IndexTypeVector<AttributeValueIndex, uint8_t> is_att_index_used;
IndexTypeVector<AttributeValueIndex, AttributeValueIndex> att_index_map;
for (int a = 0; a < mesh->num_attributes(); ++a) {
PointAttribute *const att = mesh->attribute(a);
// First detect which attribute entries are used (included in a point).
is_att_index_used.assign(att->size(), 0);
att_index_map.clear();
AttributeValueIndex::ValueType num_used_entries = 0;
for (PointIndex i(0); i < num_original_points; ++i) {
if (point_map[i] != kInvalidPointIndex) {
const AttributeValueIndex entry_id = att->mapped_index(i);
if (!is_att_index_used[entry_id]) {
is_att_index_used[entry_id] = 1;
++num_used_entries;
}
}
}
bool att_indices_changed = false;
// If there are some unused attribute entries, remap the attribute values
// in the attribute buffer.
if (num_used_entries < static_cast<int>(att->size())) {
att_index_map.resize(att->size());
num_used_entries = 0;
for (AttributeValueIndex i(0); i < static_cast<uint32_t>(att->size());
++i) {
if (is_att_index_used[i]) {
att_index_map[i] = num_used_entries;
if (i > num_used_entries) {
const uint8_t *const src_add = att->GetAddress(i);
att->buffer()->Write(
att->GetBytePos(AttributeValueIndex(num_used_entries)), src_add,
att->byte_stride());
}
++num_used_entries;
}
}
// Update the number of unique entries in the vertex buffer.
att->Resize(num_used_entries);
att_indices_changed = true;
}
// If either the points or attribute indices have changed, we need to
// update the attribute index mapping.
if (points_changed || att_indices_changed) {
if (att->is_mapping_identity()) {
// The mapping was identity. It'll remain identity only if the
// number of point and attribute indices is still the same.
if (num_used_entries != static_cast<int>(mesh->num_points())) {
// We need to create an explicit mapping.
// First we need to initialize the explicit map to the original
// number of points to recreate the original identity map.
att->SetExplicitMapping(num_original_points);
// Set the entries of the explicit map to identity.
for (PointIndex::ValueType i = 0; i < num_original_points; ++i) {
att->SetPointMapEntry(PointIndex(i), AttributeValueIndex(i));
}
}
}
if (!att->is_mapping_identity()) {
// Explicit mapping between points and local attribute indices.
for (PointIndex i(0); i < num_original_points; ++i) {
// The new point id that maps to the currently processed attribute
// entry.
const PointIndex new_point_id = point_map[i];
if (new_point_id == kInvalidPointIndex) {
continue;
}
// Index of the currently processed attribute entry in the original
// mesh.
const AttributeValueIndex original_entry_index = att->mapped_index(i);
// New index of the same entry after unused entries were removed.
const AttributeValueIndex new_entry_index =
att_indices_changed ? att_index_map[original_entry_index]
: original_entry_index;
// Update the mapping. Note that the new point index is always smaller
// than the processed index |i|, making this operation safe.
att->SetPointMapEntry(new_point_id, new_entry_index);
}
// If the number of points changed, we need to set a new explicit map
// size.
att->SetExplicitMapping(mesh->num_points());
}
}
}
}
Status MeshCleanup::MakeGeometryManifold(Mesh *mesh) {
return Status(Status::DRACO_ERROR, "Unsupported function.");
}
} // namespace draco
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