irrlicht/source/Irrlicht/CGLTFMeshFileLoader.cpp
2023-11-29 05:51:32 -05:00

361 lines
8.9 KiB
C++

#include "CGLTFMeshFileLoader.h"
#include "CMeshBuffer.h"
#include "coreutil.h"
#include "IAnimatedMesh.h"
#include "ILogger.h"
#include "IReadFile.h"
#include "irrTypes.h"
#include "os.h"
#include "path.h"
#include "S3DVertex.h"
#include "SAnimatedMesh.h"
#include "SColor.h"
#include "SMesh.h"
#include "vector3d.h"
#define TINYGLTF_IMPLEMENTATION
#include "tinygltf/tiny_gltf.h"
#include <cstddef>
#include <cstring>
#include <memory>
#include <string>
#include <utility>
#include <vector>
/* Notes on the coordinate system.
*
* glTF uses a right-handed coordinate system where +Z is the
* front-facing axis, and Irrlicht uses a left-handed coordinate
* system where -Z is the front-facing axis.
* We convert between them by reflecting the mesh across the X axis.
* Doing this correctly requires negating the Z coordinate on
* vertex positions and normals, and reversing the winding order
* of the vertex indices.
*/
// A helper function to disable tinygltf embedded image loading
static bool dummyImageLoader(tinygltf::Image *a,
const int b, std::string *c,
std::string *d,
int e,
int f,
const unsigned char * g,
int h,
void *userPointer)
{
return false;
};
namespace irr {
namespace scene {
CGLTFMeshFileLoader::BufferOffset::BufferOffset(
const std::vector<unsigned char>& buf,
const std::size_t offset)
: m_buf(buf)
, m_offset(offset)
{
}
CGLTFMeshFileLoader::BufferOffset::BufferOffset(
const CGLTFMeshFileLoader::BufferOffset& other,
const std::size_t fromOffset)
: m_buf(other.m_buf)
, m_offset(other.m_offset + fromOffset)
{
}
unsigned char CGLTFMeshFileLoader::BufferOffset::at(
const std::size_t fromOffset) const
{
return m_buf.at(m_offset + fromOffset);
}
CGLTFMeshFileLoader::CGLTFMeshFileLoader() noexcept
{
}
bool CGLTFMeshFileLoader::isALoadableFileExtension(
const io::path& filename) const
{
return core::hasFileExtension(filename, "gltf");
}
IAnimatedMesh* CGLTFMeshFileLoader::createMesh(io::IReadFile* file)
{
tinygltf::Model model {};
if (file->getSize() <= 0 || !tryParseGLTF(file, model)) {
return nullptr;
}
MeshExtractor parser(std::move(model));
SMesh* baseMesh(new SMesh {});
loadPrimitives(parser, baseMesh);
SAnimatedMesh* animatedMesh(new SAnimatedMesh {});
animatedMesh->addMesh(baseMesh);
return animatedMesh;
}
void CGLTFMeshFileLoader::loadPrimitives(
const MeshExtractor& parser,
SMesh* mesh)
{
for (std::size_t i = 0; i < parser.getMeshCount(); ++i) {
for (std::size_t j = 0; j < parser.getPrimitiveCount(i); ++j) {
auto indices = parser.getIndices(i, j);
auto vertices = parser.getVertices(i, j);
SMeshBuffer* meshbuf(new SMeshBuffer {});
meshbuf->append(vertices.data(), vertices.size(),
indices.data(), indices.size());
mesh->addMeshBuffer(meshbuf);
}
}
}
CGLTFMeshFileLoader::MeshExtractor::MeshExtractor(
const tinygltf::Model& model) noexcept
: m_model(model)
{
}
CGLTFMeshFileLoader::MeshExtractor::MeshExtractor(
const tinygltf::Model&& model) noexcept
: m_model(model)
{
}
std::vector<u16> CGLTFMeshFileLoader::MeshExtractor::getIndices(
const std::size_t meshIdx,
const std::size_t primitiveIdx) const
{
const auto accessorIdx = getIndicesAccessorIdx(meshIdx, primitiveIdx);
const auto& buf = getBuffer(accessorIdx);
std::vector<u16> indices{};
const auto count = getElemCount(accessorIdx);
for (std::size_t i = 0; i < count; ++i) {
std::size_t elemIdx = count - i - 1;
indices.push_back(readPrimitive<u16>(
BufferOffset(buf, elemIdx * sizeof(u16))));
}
return indices;
}
std::vector<video::S3DVertex> CGLTFMeshFileLoader::MeshExtractor::getVertices(
const std::size_t meshIdx,
const std::size_t primitiveIdx) const
{
const auto positionAccessorIdx = getPositionAccessorIdx(
meshIdx, primitiveIdx);
std::vector<vertex_t> vertices{};
vertices.resize(getElemCount(positionAccessorIdx));
copyPositions(positionAccessorIdx, vertices);
const auto normalAccessorIdx = getNormalAccessorIdx(
meshIdx, primitiveIdx);
if (normalAccessorIdx != static_cast<std::size_t>(-1)) {
copyNormals(normalAccessorIdx, vertices);
}
const auto tCoordAccessorIdx = getTCoordAccessorIdx(
meshIdx, primitiveIdx);
if (tCoordAccessorIdx != static_cast<std::size_t>(-1)) {
copyTCoords(tCoordAccessorIdx, vertices);
}
return vertices;
}
std::size_t CGLTFMeshFileLoader::MeshExtractor::getMeshCount() const
{
return m_model.meshes.size();
}
std::size_t CGLTFMeshFileLoader::MeshExtractor::getPrimitiveCount(
const std::size_t meshIdx) const
{
return m_model.meshes[meshIdx].primitives.size();
}
template <typename T>
T CGLTFMeshFileLoader::MeshExtractor::readPrimitive(
const BufferOffset& readFrom)
{
unsigned char d[sizeof(T)]{};
for (std::size_t i = 0; i < sizeof(T); ++i) {
d[i] = readFrom.at(i);
}
T dest;
std::memcpy(&dest, d, sizeof(dest));
return dest;
}
core::vector2df CGLTFMeshFileLoader::MeshExtractor::readVec2DF(
const CGLTFMeshFileLoader::BufferOffset& readFrom)
{
return core::vector2df(readPrimitive<float>(readFrom),
readPrimitive<float>(BufferOffset(readFrom, sizeof(float))));
}
core::vector3df CGLTFMeshFileLoader::MeshExtractor::readVec3DF(
const BufferOffset& readFrom,
const float scale)
{
return core::vector3df(
scale * readPrimitive<float>(readFrom),
scale * readPrimitive<float>(BufferOffset(readFrom, sizeof(float))),
-scale * readPrimitive<float>(BufferOffset(readFrom, 2 *
sizeof(float))));
}
void CGLTFMeshFileLoader::MeshExtractor::copyPositions(
const std::size_t accessorIdx,
std::vector<vertex_t>& vertices) const
{
const auto& buffer = getBuffer(accessorIdx);
const auto count = getElemCount(accessorIdx);
for (std::size_t i = 0; i < count; i++) {
const auto v = readVec3DF(BufferOffset(buffer,
3 * sizeof(float) * i), getScale());
vertices[i].Pos = v;
}
}
void CGLTFMeshFileLoader::MeshExtractor::copyNormals(
const std::size_t accessorIdx,
std::vector<vertex_t>& vertices) const
{
const auto& buffer = getBuffer(accessorIdx);
const auto count = getElemCount(accessorIdx);
for (std::size_t i = 0; i < count; i++) {
const auto n = readVec3DF(BufferOffset(buffer,
3 * sizeof(float) * i));
vertices[i].Normal = n;
}
}
void CGLTFMeshFileLoader::MeshExtractor::copyTCoords(
const std::size_t accessorIdx,
std::vector<vertex_t>& vertices) const
{
const auto& buffer = getBuffer(accessorIdx);
const auto count = getElemCount(accessorIdx);
for (std::size_t i = 0; i < count; ++i) {
const auto t = readVec2DF(BufferOffset(buffer,
2 * sizeof(float) * i));
vertices[i].TCoords = t;
}
}
float CGLTFMeshFileLoader::MeshExtractor::getScale() const
{
if (m_model.nodes[0].scale.size() > 0) {
return static_cast<float>(m_model.nodes[0].scale[0]);
}
return 1.0f;
}
std::size_t CGLTFMeshFileLoader::MeshExtractor::getElemCount(
const std::size_t accessorIdx) const
{
return m_model.accessors[accessorIdx].count;
}
CGLTFMeshFileLoader::BufferOffset CGLTFMeshFileLoader::MeshExtractor::getBuffer(
const std::size_t accessorIdx) const
{
const auto& accessor = m_model.accessors[accessorIdx];
const auto& view = m_model.bufferViews[accessor.bufferView];
const auto& buffer = m_model.buffers[view.buffer];
return BufferOffset(buffer.data, view.byteOffset);
}
std::size_t CGLTFMeshFileLoader::MeshExtractor::getIndicesAccessorIdx(
const std::size_t meshIdx,
const std::size_t primitiveIdx) const
{
return m_model.meshes[meshIdx].primitives[primitiveIdx].indices;
}
std::size_t CGLTFMeshFileLoader::MeshExtractor::getPositionAccessorIdx(
const std::size_t meshIdx,
const std::size_t primitiveIdx) const
{
return m_model.meshes[meshIdx].primitives[primitiveIdx]
.attributes.find("POSITION")->second;
}
std::size_t CGLTFMeshFileLoader::MeshExtractor::getNormalAccessorIdx(
const std::size_t meshIdx,
const std::size_t primitiveIdx) const
{
const auto& attributes = m_model.meshes[meshIdx]
.primitives[primitiveIdx].attributes;
const auto result = attributes.find("NORMAL");
if (result == attributes.end()) {
return -1;
} else {
return result->second;
}
}
std::size_t CGLTFMeshFileLoader::MeshExtractor::getTCoordAccessorIdx(
const std::size_t meshIdx,
const std::size_t primitiveIdx) const
{
const auto& attributes = m_model.meshes[meshIdx]
.primitives[primitiveIdx].attributes;
const auto result = attributes.find("TEXCOORD_0");
if (result == attributes.end()) {
return -1;
} else {
return result->second;
}
}
bool CGLTFMeshFileLoader::tryParseGLTF(io::IReadFile* file,
tinygltf::Model& model)
{
tinygltf::TinyGLTF loader {};
// Stop embedded textures from making model fail to load
loader.SetImageLoader(dummyImageLoader, nullptr);
std::string err {};
std::string warn {};
auto buf = std::make_unique<char[]>(file->getSize());
file->read(buf.get(), file->getSize());
if (warn != "") {
os::Printer::log(warn.c_str(), ELL_WARNING);
}
if (err != "") {
os::Printer::log(err.c_str(), ELL_ERROR);
return false;
}
return loader.LoadASCIIFromString(&model, &err, &warn, buf.get(),
file->getSize(), "", 1);
}
} // namespace scene
} // namespace irr