irrlicht/source/Irrlicht/CGLTFMeshFileLoader.cpp
2024-04-18 07:21:56 -05:00

159 lines
4.0 KiB
C++

#include "CGLTFMeshFileLoader.h"
#include "CMeshBuffer.h"
#include "coreutil.h"
#include "IAnimatedMesh.h"
#include "IReadFile.h"
#include "irrTypes.h"
#include "path.h"
#include "S3DVertex.h"
#include "SAnimatedMesh.h"
#include "SColor.h"
#include "SMesh.h"
#include "vector3d.h"
#define TINYGLTF_IMPLEMENTATION
#include <tiny_gltf.h>
#include <cstddef>
#include <memory>
#include <string>
class BufferOffset
{
public:
BufferOffset(const std::vector<unsigned char>& buf,
const std::size_t offset)
: m_buf(buf)
, m_offset(offset)
{
}
BufferOffset(const BufferOffset& other, const std::size_t fromOffset)
: m_buf(other.m_buf)
, m_offset(other.m_offset + fromOffset)
{
}
unsigned char at(const std::size_t fromOffset) const
{
return m_buf.at(m_offset + fromOffset);
}
private:
const std::vector<unsigned char>& m_buf;
std::size_t m_offset;
};
namespace irr
{
namespace scene
{
static bool tryParseGLTF(io::IReadFile* file, tinygltf::Model& model)
{
tinygltf::TinyGLTF loader {};
std::string err {};
std::string warn {};
auto buf = std::make_unique<char[]>(file->getSize());
file->read(buf.get(), file->getSize());
return loader.LoadASCIIFromString(
&model, &err, &warn, buf.get(), file->getSize(), "", 1);
}
template <class T>
static T readPrimative(const BufferOffset& readFrom) {
unsigned char d[sizeof(T)]{};
for (std::size_t i = 0; i < sizeof(T); ++i) {
d[i] = readFrom.at(i);
}
return *reinterpret_cast<T*>(d);
}
static core::vector3df readVector(const BufferOffset& readFrom) {
// glTF coordinates are right-handed, minetest ones are left-handed
// 1 glTF coordinate is equivalent to 10 Irrlicht coordinates
return core::vector3df(
-1.0 * readPrimative<float>(readFrom),
1.0 * readPrimative<float>(BufferOffset(readFrom, sizeof(float))),
1.0 * readPrimative<float>(BufferOffset(readFrom, 2 * sizeof(float))));
}
static u16* readIndices(const BufferOffset& readFrom, const std::size_t count)
{
auto* indices = new u16[count]{};
for (std::size_t i = 0; i < count; ++i) {
indices[i] = readPrimative<u16>(BufferOffset(readFrom, i * sizeof(u16)));
}
return indices;
}
video::S3DVertex* getVertices(const tinygltf::Model& model, const std::size_t accessorId)
{
const auto& view = model.bufferViews[
model.accessors[accessorId].bufferView];
const auto& buffer = model.buffers[view.buffer];
const auto v1 = readVector(BufferOffset(
buffer.data, view.byteOffset));
const auto v2 = readVector(BufferOffset(
buffer.data, view.byteOffset + (3 * sizeof(float))));
const auto v3 = readVector(BufferOffset(
buffer.data, view.byteOffset + (6 * sizeof(float))));
return (new video::S3DVertex[3] {
{v1, {0.0f, 0.0f, 1.0f}, {}, {0.0f, 0.0f}},
{v2, {0.0f, 0.0f, 1.0f}, {}, {1.0f, 0.0f}},
{v3, {0.0f, 0.0f, 1.0f}, {}, {0.0f, 1.0f}} } );
}
u16* getIndices(const tinygltf::Model& model, const std::size_t accessorId)
{
const auto& indicesView = model.bufferViews[
model.accessors[accessorId].bufferView];
const auto& indicesBuffer = model.buffers[indicesView.buffer];
return readIndices(
BufferOffset(indicesBuffer.data, indicesView.byteOffset),
model.accessors[0].count);
}
CGLTFMeshFileLoader::CGLTFMeshFileLoader()
{
}
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;
}
auto* indices = getIndices(model, 0);
auto* vertices = getVertices(model, 1);
SMeshBuffer* meshbuf { new SMeshBuffer {} };
meshbuf->append(vertices, model.accessors[1].count,
indices, model.accessors[0].count);
SMesh* mesh { new SMesh {} };
mesh->addMeshBuffer(meshbuf);
SAnimatedMesh* animatedMesh { new SAnimatedMesh {} };
animatedMesh->addMesh(mesh);
return animatedMesh;
}
} // namespace scene
} // namespace irr