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IfcOpenShell/src/serializers/GltfSerializer.cpp
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/********************************************************************************
* *
* This file is part of IfcOpenShell. *
* *
* IfcOpenShell is free software: you can redistribute it and/or modify *
* it under the terms of the Lesser GNU General Public License as published by *
* the Free Software Foundation, either version 3.0 of the License, or *
* (at your option) any later version. *
* *
* IfcOpenShell is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* Lesser GNU General Public License for more details. *
* *
* You should have received a copy of the Lesser GNU General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/>. *
* *
********************************************************************************/
#ifdef WITH_GLTF
#include "GltfSerializer.h"
#include "../ifcparse/utils.h"
#include <iterator>
static const uint32_t GLTF = 0x46546C67U;
static const uint32_t JSON = 0x4E4F534A;
static const uint32_t BIN = 0x004E4942;
static const uint32_t CT_BYTE = 5120;
static const uint32_t CT_UNSIGNED_BYTE = 5121;
static const uint32_t CT_SHORT = 5122;
static const uint32_t CT_UNSIGNED_SHORT = 5123;
static const uint32_t CT_UNSIGNED_INT = 5125;
static const uint32_t CT_FLOAT = 5126;
static const uint32_t PRIM_POINTS = 0;
static const uint32_t PRIM_LINES = 1;
static const uint32_t PRIM_LINE_LOOP = 2;
static const uint32_t PRIM_LINE_STRIP = 3;
static const uint32_t PRIM_TRIANGLES = 4;
static const uint32_t PRIM_TRIANGLE_STRIP = 5;
static const uint32_t PRIM_TRIANGLE_FAN = 6;
GltfSerializer::GltfSerializer(const std::string& filename, const SerializerSettings& settings)
: WriteOnlyGeometrySerializer(settings)
, filename_(filename)
, tmp_filename1_(filename + ".indices.tmp")
, tmp_filename2_(filename + ".vertices.tmp")
, fstream_(IfcUtil::path::from_utf8(filename).c_str(), std::ios_base::binary)
, tmp_fstream1_(IfcUtil::path::from_utf8(tmp_filename1_).c_str(), std::ios_base::binary)
, tmp_fstream2_(IfcUtil::path::from_utf8(tmp_filename2_).c_str(), std::ios_base::binary)
{}
GltfSerializer::~GltfSerializer() {
tmp_fstream1_.close();
tmp_fstream2_.close();
IfcUtil::path::delete_file(tmp_filename1_);
IfcUtil::path::delete_file(tmp_filename2_);
}
bool GltfSerializer::ready() {
return fstream_.is_open() && tmp_fstream1_.is_open() && tmp_fstream2_.is_open();
}
void GltfSerializer::writeHeader() {
json_["asset"]["generator"] = "IfcOpenShell IfcConvert " IFCOPENSHELL_VERSION;
json_["asset"]["version"] = "2.0";
json_["scene"] = 0;
node_array_ = json::array();
json_["accessors"] = json::array();
json_["scenes"] = json::array();
json_["nodes"] = json::array();
json_["meshes"] = json::array();
json_["materials"] = json::array();
}
int GltfSerializer::writeMaterial(const IfcGeom::Material& style) {
auto it = materials_.find(style.name());
if (it != materials_.end()) {
return it->second;
}
int idx = json_["materials"].size();
materials_[style.name()] = idx;
std::array<double, 4> base;
base.fill(1.0);
if (style.hasDiffuse()) {
for (int i = 0; i < 3; ++i) {
base[i] = style.diffuse()[i];
}
}
if (style.hasTransparency()) {
base[3] = 1. - style.transparency();
}
json_["materials"].push_back({ {"pbrMetallicRoughness", {{"baseColorFactor", base}, {"metallicFactor", 0}}} });
if (style.hasTransparency() && style.transparency() > 1.e-9) {
json_["materials"].back()["alphaMode"] = "BLEND";
}
return idx;
}
template <size_t N>
struct stride_name { static const char* const value; };
template <>
const char* const stride_name<1U>::value = "SCALAR";
template <>
const char* const stride_name<3U>::value = "VEC3";
template <typename T>
struct component_type { static const uint32_t value; };
template <>
const uint32_t component_type<int>::value = CT_UNSIGNED_INT;
template <>
const uint32_t component_type<float>::value = CT_FLOAT;
template <size_t N, typename It>
size_t write_accessor(json& j, std::ofstream& ofs, It begin, It end) {
auto num = std::distance(begin, end) / N;
json accessor = json::object();
accessor["bufferView"] = N == 1 ? 0 : 1;
accessor["byteOffset"] = (size_t)ofs.tellp();
accessor["componentType"] = component_type<typename It::value_type>::value;
accessor["count"] = num;
std::array<typename It::value_type, N> min, max;
min.fill(std::numeric_limits<typename It::value_type>::max());
max.fill(std::numeric_limits<typename It::value_type>::lowest());
for (auto it = begin; it != end; it += N) {
for (size_t i = 0; i < N; ++i) {
const float& v = *(it + i);
if (v < min[i]) {
min[i] = v;
}
if (v > max[i]) {
max[i] = v;
}
}
}
accessor["min"] = min;
accessor["max"] = max;
accessor["type"] = stride_name<N>::value;
ofs.write((const char*)&*begin, sizeof(typename It::value_type) * num * N);
j["accessors"].push_back(accessor);
return j["accessors"].size() - 1;
}
void GltfSerializer::write(const IfcGeom::TriangulationElement* o) {
if (o->geometry().material_ids().empty()) {
return;
}
node_array_.push_back(json_["nodes"].size());
const std::vector<double>& m = o->transformation().matrix().data();
// nb: note that this contains the Y-UP transform as well.
const std::array<double, 16> matrix_flat = {
m[0], m[ 2], -m[ 1], 0,
m[3], m[ 5], -m[ 4], 0,
m[6], m[ 8], -m[ 7], 0,
m[9], m[11], -m[10], 1
};
static const std::array<double, 16> identity_matrix = {1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1};
json node;
if (matrix_flat != identity_matrix) {
// glTF validator complains about identity matrices
node["matrix"] = matrix_flat;
}
node["name"] = object_id(o);
int current_mesh_index;
// See if this mesh has already been processed
auto it = meshes_.find(o->geometry().id());
if (it == meshes_.end()) {
auto mid1 = o->geometry().material_ids().begin();
auto mid0 = mid1;
std::vector<int>::const_iterator fid0;
int stride;
int primitive_type;
if (!o->geometry().faces().empty()) {
stride = 3;
fid0 = o->geometry().faces().begin();
primitive_type = PRIM_TRIANGLES;
} else {
stride = 2;
fid0 = o->geometry().edges().begin();
primitive_type = PRIM_LINES;
}
json mesh;
mesh["name"] = o->geometry().id();
while (true) {
// In glTF we need to decompose a mesh into several primitives
// with a constant material. In the triangulations coming from
// IfcOpenShell the materials are encoded in an additional set
// of indices. Therefore we loop over the material indices to
// find equal ranges of materials. Triangle indices then need
// to be updated to reference the vertices only for the current
// material.
mid1++;
if ((mid1 == o->geometry().material_ids().end()) || (*mid1 != *mid0)) {
auto n = std::distance(mid0, mid1);
auto fid1 = fid0 + n * stride;
auto idx_range = std::minmax_element(fid0, fid1);
const auto& idx_begin = *idx_range.first;
const auto& idx_end = *idx_range.second + 1;
std::vector<int> idx_transformed;
idx_transformed.reserve((n * stride));
std::transform(fid0, fid1, std::back_inserter(idx_transformed), [idx_begin](int i) {
return i - idx_begin;
});
json primitive = json::object();
primitive["indices"] = write_accessor<1U>(json_, tmp_fstream1_, idx_transformed.begin(), idx_transformed.end());
auto vbegin = o->geometry().verts().begin();
std::vector<float> vf(vbegin + idx_begin * 3, vbegin + idx_end * 3);
primitive["attributes"]["POSITION"] = write_accessor<3U>(json_, tmp_fstream2_, vf.begin(), vf.end());
if (o->geometry().normals().size()) {
auto nbegin = o->geometry().normals().begin();
std::vector<float> nf(nbegin + idx_begin * 3, nbegin + idx_end * 3);
primitive["attributes"]["NORMAL"] = write_accessor<3U>(json_, tmp_fstream2_, nf.begin(), nf.end());
}
primitive["material"] = writeMaterial(o->geometry().materials()[*mid0]);
primitive["mode"] = primitive_type;
mesh["primitives"].push_back(primitive);
if (mid1 == o->geometry().material_ids().end()) {
break;
}
mid0 = mid1;
fid0 = fid1;
}
}
json_["meshes"].push_back(mesh);
meshes_[o->geometry().id()] = current_mesh_index = json_["meshes"].size() - 1;
} else {
current_mesh_index = it->second;
}
node["mesh"] = current_mesh_index;
json_["nodes"].push_back(node);
}
template <uint32_t>
struct padding_char { static const char value; };
template <>
const char padding_char<JSON>::value = ' ';
template <>
const char padding_char<BIN>::value = '\x00';
uint32_t padding_for(uint32_t length) {
return ((4 - (length % 4)) % 4);
}
template <uint32_t iden>
void write_padding(std::ostream& fs, uint32_t N) {
uint32_t padding = padding_for(N);
for (uint32_t i = 0; i < padding; ++i) {
fs.put(padding_char<iden>::value);
}
}
template <uint32_t iden>
void write_header(std::ostream& fs, uint32_t N) {
uint32_t padding = padding_for(N);
uint32_t header[] = { N + padding, iden };
fs.write((const char*)header, sizeof(header));
}
template <uint32_t iden, typename It>
void write_block(std::ostream& fs, It begin, It end) {
uint32_t N = std::distance(begin, end);
write_header<iden>(fs, N);
fs.write((const char*)&*begin, N);
write_padding<iden>(fs, N);
}
void GltfSerializer::finalize() {
tmp_fstream1_.close();
tmp_fstream2_.close();
std::vector<char> binary_contents;
// nb: uint32_t is the max buffer size in glTF
uint32_t indices_length, binary_length;
{
std::ifstream ifs(IfcUtil::path::from_utf8(tmp_filename1_).c_str(), std::ios::binary);
ifs.ignore(std::numeric_limits<std::streamsize>::max());
indices_length = ifs.gcount();
}
{
std::ifstream ifs(IfcUtil::path::from_utf8(tmp_filename2_).c_str(), std::ios::binary);
ifs.ignore(std::numeric_limits<std::streamsize>::max());
binary_length = indices_length + ifs.gcount();
}
json scene_0;
scene_0["nodes"] = node_array_;
json_["scenes"].push_back(scene_0);
json_["bufferViews"].push_back({ {"buffer", 0}, { "byteLength", indices_length } });
json_["bufferViews"].push_back({ {"buffer", 0}, {"byteStride", 12}, { "byteOffset", indices_length }, { "byteLength", binary_length - indices_length } });
json_["buffers"].push_back({ {"byteLength", binary_length} });
std::string json_contents = json_.dump();
uint32_t json_length = (uint32_t) json_contents.size();
uint32_t header[] = { GLTF, 2U, 12 + 8 + json_length + padding_for(json_length) + 8 + binary_length + padding_for(binary_length) };
fstream_.write((const char*)header, sizeof(header));
write_block<JSON>(fstream_, json_contents.begin(), json_contents.end());
write_header<BIN>(fstream_, binary_length);
{
std::ifstream ifs(IfcUtil::path::from_utf8(tmp_filename1_).c_str(), std::ios::binary);
fstream_ << ifs.rdbuf();
}
{
std::ifstream ifs(IfcUtil::path::from_utf8(tmp_filename2_).c_str(), std::ios::binary);
fstream_ << ifs.rdbuf();
}
write_padding<BIN>(fstream_, binary_length);
}
#endif