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[glTF2] Implemented reading binary glTF2 (glb) files

pull/1584/head
Patrick Dähne 2017-11-20 14:59:05 +01:00
parent e1837b6cc8
commit 6cbfd5b977
3 changed files with 120 additions and 16 deletions
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29
code/glTF2Asset.h
View File

@ -192,15 +192,31 @@ namespace glTF2
#include "./../include/assimp/Compiler/pushpack1.h"
#endif
//! For binary .glb files
//! 12-byte header (+ the JSON + a "body" data section)
struct GLB_Header
{
uint8_t magic[4]; //!< Magic number: "glTF"
uint32_t version; //!< Version number (always 2 as of the last update)
uint32_t length; //!< Total length of the Binary glTF, including header, scene, and body, in bytes
} PACK_STRUCT;
struct GLB_Chunk
{
uint32_t chunkLength;
uint32_t chunkType;
} PACK_STRUCT;
#ifdef ASSIMP_API
#include "./../include/assimp/Compiler/poppack1.h"
#endif
//! Values for the GLB_Header::sceneFormat field
enum SceneFormat
//! Values for the GLB_Chunk::chunkType field
enum ChunkType
{
SceneFormat_JSON = 0
ChunkType_JSON = 0x4E4F534A,
ChunkType_BIN = 0x004E4942
};
//! Values for the mesh primitive modes
@ -1086,7 +1102,10 @@ namespace glTF2
}
//! Main function
void Load(const std::string& file);
void Load(const std::string& file, bool isBinary = false);
//! Enables binary encoding on the asset
void SetAsBinary();
//! Search for an available name, starting from the given strings
std::string FindUniqueID(const std::string& str, const char* suffix);
@ -1095,6 +1114,8 @@ namespace glTF2
{ return mBodyBuffer; }
private:
void ReadBinaryHeader(IOStream& stream, std::vector<char>& sceneData);
void ReadExtensionsUsed(Document& doc);
IOStream* OpenFile(std::string path, const char* mode, bool absolute = false);

87
code/glTF2Asset.inl
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@ -1037,7 +1037,72 @@ inline void AssetMetadata::Read(Document& doc)
// Asset methods implementation
//
inline void Asset::Load(const std::string& pFile)
inline void Asset::ReadBinaryHeader(IOStream& stream, std::vector<char>& sceneData)
{
GLB_Header header;
if (stream.Read(&header, sizeof(header), 1) != 1) {
throw DeadlyImportError("GLTF: Unable to read the file header");
}
if (strncmp((char*)header.magic, AI_GLB_MAGIC_NUMBER, sizeof(header.magic)) != 0) {
throw DeadlyImportError("GLTF: Invalid binary glTF file");
}
AI_SWAP4(header.version);
asset.version = to_string(header.version);
if (header.version != 2) {
throw DeadlyImportError("GLTF: Unsupported binary glTF version");
}
GLB_Chunk chunk;
if (stream.Read(&chunk, sizeof(chunk), 1) != 1) {
throw DeadlyImportError("GLTF: Unable to read JSON chunk");
}
AI_SWAP4(chunk.chunkLength);
AI_SWAP4(chunk.chunkType);
if (chunk.chunkType != ChunkType_JSON) {
throw DeadlyImportError("GLTF: JSON chunk missing");
}
// read the scene data
mSceneLength = chunk.chunkLength;
sceneData.resize(mSceneLength + 1);
sceneData[mSceneLength] = '\0';
if (stream.Read(&sceneData[0], 1, mSceneLength) != mSceneLength) {
throw DeadlyImportError("GLTF: Could not read the file contents");
}
uint32_t padding = ((chunk.chunkLength + 3) & ~3) - chunk.chunkLength;
if (padding > 0) {
stream.Seek(padding, aiOrigin_CUR);
}
AI_SWAP4(header.length);
mBodyOffset = 12 + 8 + chunk.chunkLength + padding + 8;
if (header.length >= mBodyOffset) {
if (stream.Read(&chunk, sizeof(chunk), 1) != 1) {
throw DeadlyImportError("GLTF: Unable to read BIN chunk");
}
AI_SWAP4(chunk.chunkLength);
AI_SWAP4(chunk.chunkType);
if (chunk.chunkType != ChunkType_BIN) {
throw DeadlyImportError("GLTF: BIN chunk missing");
}
mBodyLength = chunk.chunkLength;
}
else {
mBodyOffset = mBodyLength = 0;
}
}
inline void Asset::Load(const std::string& pFile, bool isBinary)
{
mCurrentAssetDir.clear();
int pos = std::max(int(pFile.rfind('/')), int(pFile.rfind('\\')));
@ -1048,17 +1113,26 @@ inline void Asset::Load(const std::string& pFile)
throw DeadlyImportError("GLTF: Could not open file for reading");
}
// is binary? then read the header
std::vector<char> sceneData;
if (isBinary) {
SetAsBinary(); // also creates the body buffer
ReadBinaryHeader(*stream, sceneData);
}
else {
mSceneLength = stream->FileSize();
mBodyLength = 0;
// read the scene data
std::vector<char> sceneData(mSceneLength + 1);
sceneData.resize(mSceneLength + 1);
sceneData[mSceneLength] = '\0';
if (stream->Read(&sceneData[0], 1, mSceneLength) != mSceneLength) {
throw DeadlyImportError("GLTF: Could not read the file contents");
}
}
// parse the JSON document
@ -1110,6 +1184,15 @@ inline void Asset::Load(const std::string& pFile)
}
}
inline void Asset::SetAsBinary()
{
if (!mBodyBuffer) {
mBodyBuffer = buffers.Create("binary_glTF");
mBodyBuffer->MarkAsSpecial();
}
}
inline void Asset::ReadExtensionsUsed(Document& doc)
{
Value* extsUsed = FindArray(doc, "extensionsUsed");

8
code/glTF2Importer.cpp
View File

@ -74,7 +74,7 @@ static const aiImporterDesc desc = {
"",
"",
"",
aiImporterFlags_SupportTextFlavour | aiImporterFlags_LimitedSupport | aiImporterFlags_Experimental,
aiImporterFlags_SupportTextFlavour | aiImporterFlags_SupportBinaryFlavour | aiImporterFlags_LimitedSupport | aiImporterFlags_Experimental,
0,
0,
0,
@ -103,13 +103,13 @@ bool glTF2Importer::CanRead(const std::string& pFile, IOSystem* pIOHandler, bool
{
const std::string &extension = GetExtension(pFile);
if (extension != "gltf") // We currently can't read glTF2 binary files (.glb), yet
if (extension != "gltf" && extension != "glb")
return false;
if (checkSig && pIOHandler) {
glTF2::Asset asset(pIOHandler);
try {
asset.Load(pFile);
asset.Load(pFile, extension == "glb");
std::string version = asset.asset.version;
return !version.empty() && version[0] == '2';
} catch (...) {
@ -639,7 +639,7 @@ void glTF2Importer::InternReadFile(const std::string& pFile, aiScene* pScene, IO
// read the asset file
glTF2::Asset asset(pIOHandler);
asset.Load(pFile);
asset.Load(pFile, GetExtension(pFile) == "glb");
//
// Copy the data out