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When in permissive mode, handle the situation where the

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recorded component type does not match the required type
for the actual number of stored points

This situation arises when decoding certain malformed files, most
notably it's seen in glb tiles from Google Earth's 3d tileset.

It's a port of the workaround used by Cesium native here:

d9172461e2/CesiumGltfReader/src/decodeDraco.cpp (L101)
This commit is contained in:
Nyall Dawson 2023-08-24 13:25:34 +10:00
parent acf1e8a2b1
commit 6e3d666cf3
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GPG Key ID: D853AA00D2F6AFD0
1 changed files with 46 additions and 11 deletions
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57
tiny_gltf.h
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@ -4873,8 +4873,9 @@ static bool GetAttributeForAllPoints(uint32_t componentType, draco::Mesh *mesh,
}
static bool ParseDracoExtension(Primitive *primitive, Model *model,
std::string *err,
const Value &dracoExtensionValue) {
std::string *err, std::string *warn,
const Value &dracoExtensionValue,
ParseStrictness strictness) {
(void)err;
auto bufferViewValue = dracoExtensionValue.Get("bufferView");
if (!bufferViewValue.IsInt()) return false;
@ -4906,6 +4907,33 @@ static bool ParseDracoExtension(Primitive *primitive, Model *model,
// create new bufferView for indices
if (primitive->indices >= 0) {
if (strictness == ParseStrictness::PERMISSIVE) {
const draco::PointIndex::ValueType numPoint = mesh->num_points();
// handle the situation where the stored component type does not match the
// required type for the actual number of stored points
int supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE;
if (numPoint < static_cast<draco::PointIndex::ValueType>(
std::numeric_limits<uint8_t>::max())) {
supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE;
} else if (
numPoint < static_cast<draco::PointIndex::ValueType>(
std::numeric_limits<uint16_t>::max())) {
supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT;
} else {
supposedComponentType = TINYGLTF_COMPONENT_TYPE_UNSIGNED_INT;
}
if (supposedComponentType > model->accessors[primitive->indices].componentType) {
model->accessors[primitive->indices].componentType = supposedComponentType;
if (warn) {
(*warn) +=
"GLTF component type " + std::to_string(model->accessors[primitive->indices].componentType) +
" is not sufficient for number of stored points,"
" treating as " + std::to_string(supposedComponentType) + "\n";
}
}
}
int32_t componentSize = GetComponentSizeInBytes(
model->accessors[primitive->indices].componentType);
Buffer decodedIndexBuffer;
@ -4971,9 +4999,11 @@ static bool ParseDracoExtension(Primitive *primitive, Model *model,
}
#endif
static bool ParsePrimitive(Primitive *primitive, Model *model, std::string *err,
static bool ParsePrimitive(Primitive *primitive, Model *model,
std::string *err, std::string *warn,
const detail::json &o,
bool store_original_json_for_extras_and_extensions) {
bool store_original_json_for_extras_and_extensions,
ParseStrictness strictness) {
int material = -1;
ParseIntegerProperty(&material, err, o, "material", false);
primitive->material = material;
@ -5022,18 +5052,21 @@ static bool ParsePrimitive(Primitive *primitive, Model *model, std::string *err,
auto dracoExtension =
primitive->extensions.find("KHR_draco_mesh_compression");
if (dracoExtension != primitive->extensions.end()) {
ParseDracoExtension(primitive, model, err, dracoExtension->second);
ParseDracoExtension(primitive, model, err, warn, dracoExtension->second, strictness);
}
#else
(void)model;
(void)warn;
#endif
return true;
}
static bool ParseMesh(Mesh *mesh, Model *model, std::string *err,
static bool ParseMesh(Mesh *mesh, Model *model,
std::string *err, std::string *warn,
const detail::json &o,
bool store_original_json_for_extras_and_extensions) {
bool store_original_json_for_extras_and_extensions,
ParseStrictness strictness) {
ParseStringProperty(&mesh->name, err, o, "name", false);
mesh->primitives.clear();
@ -5046,8 +5079,9 @@ static bool ParseMesh(Mesh *mesh, Model *model, std::string *err,
detail::ArrayBegin(detail::GetValue(primObject));
i != primEnd; ++i) {
Primitive primitive;
if (ParsePrimitive(&primitive, model, err, *i,
store_original_json_for_extras_and_extensions)) {
if (ParsePrimitive(&primitive, model, err, warn, *i,
store_original_json_for_extras_and_extensions,
strictness)) {
// Only add the primitive if the parsing succeeds.
mesh->primitives.emplace_back(std::move(primitive));
}
@ -6078,8 +6112,9 @@ bool TinyGLTF::LoadFromString(Model *model, std::string *err, std::string *warn,
return false;
}
Mesh mesh;
if (!ParseMesh(&mesh, model, err, o,
store_original_json_for_extras_and_extensions_)) {
if (!ParseMesh(&mesh, model, err, warn, o,
store_original_json_for_extras_and_extensions_,
strictness_)) {
return false;
}