Add binary glTF (.glb) support

doc/lua_api.md

@@ -274,7 +274,7 @@ Accepted formats are:
 
     images: .png, .jpg, .tga, (deprecated:) .bmp
     sounds: .ogg vorbis
-    models: .x, .b3d, .obj, .gltf (Minetest 5.10 or newer)
+    models: .x, .b3d, .obj, .gltf, .glb (Minetest 5.10 or newer)
 
 Other formats won't be sent to the client (e.g. you can store .blend files
 in a folder for convenience, without the risk that such files are transferred)
@@ -302,6 +302,9 @@ The glTF model file format for now only serves as a
 more modern alternative to the other static model file formats;
 it unlocks no special rendering features.
 
+Binary glTF (`.glb`) files are supported and recommended over `.gltf` files
+due to their space savings.
+
 This means that many glTF features are not supported *yet*, including:
 
 * Animation

games/devtest/mods/gltf/init.lua

@@ -18,6 +18,14 @@ do
 	register_entity("blender_cube", cube_textures)
 	register_entity("blender_cube_scaled", cube_textures)
 	register_entity("blender_cube_matrix_transform", cube_textures)
+	minetest.register_entity("gltf:blender_cube_glb", {
+		initial_properties = {
+			visual = "mesh",
+			mesh = "gltf_blender_cube.glb",
+			textures = cube_textures,
+			backface_culling = true,
+		},
+	})
 end
 register_entity("snow_man", {"gltf_snow_man.png"})
 register_entity("spider", {"gltf_spider.png"})

irr/src/CGLTFMeshFileLoader.cpp

@@ -14,8 +14,6 @@
 #include "vector3d.h"
 #include "os.h"
 
-#include "tiniergltf.hpp"
-
 #include <array>
 #include <cstddef>
 #include <cstring>
@@ -303,13 +301,11 @@ std::array<f32, N> SelfType::getNormalizedValues(
 	return values;
 }
 
-/**
- * The most basic portion of the code base. This tells irllicht if this file has a .gltf extension.
-*/
 bool SelfType::isALoadableFileExtension(
 		const io::path& filename) const
 {
-	return core::hasFileExtension(filename, "gltf");
+	return core::hasFileExtension(filename, "gltf") ||
+			core::hasFileExtension(filename, "glb");
 }
 
 /**
@@ -663,6 +659,7 @@ void SelfType::MeshExtractor::copyTCoords(
 */
 std::optional<tiniergltf::GlTF> SelfType::tryParseGLTF(io::IReadFile* file)
 {
+	const bool isGlb = core::hasFileExtension(file->getFileName(), "glb");
 	auto size = file->getSize();
 	if (size < 0) // this can happen if `ftell` fails
 		return std::nullopt;
@@ -671,15 +668,11 @@ std::optional<tiniergltf::GlTF> SelfType::tryParseGLTF(io::IReadFile* file)
 		return std::nullopt;
 	// We probably don't need this, but add it just to be sure.
 	buf[size] = '\0';
-	Json::CharReaderBuilder builder;
-	const std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
-	Json::Value json;
-	JSONCPP_STRING err;
-	if (!reader->parse(buf.get(), buf.get() + size, &json, &err)) {
-		return std::nullopt;
-	}
 	try {
-		return tiniergltf::GlTF(json);
+		if (isGlb)
+			return tiniergltf::readGlb(buf.get(), size);
+		else
+			return tiniergltf::readGlTF(buf.get(), size);
 	} catch (const std::runtime_error &e) {
 		os::Printer::log("glTF loader", e.what(), ELL_ERROR);
 		return std::nullopt;

lib/tiniergltf/tiniergltf.hpp

@@ -1,6 +1,9 @@
 #pragma once
 
 #include <json/json.h>
+#include "util/base64.h"
+
+#include <cstdint>
 #include <functional>
 #include <stack>
 #include <string>
@@ -13,7 +16,6 @@
 #include <stdexcept>
 #include <unordered_map>
 #include <unordered_set>
-#include "util/base64.h"
 
 namespace tiniergltf {
 
@@ -460,7 +462,8 @@ struct Buffer {
 	std::optional<std::string> name;
 	std::string data;
 	Buffer(const Json::Value &o,
-			const std::function<std::string(const std::string &uri)> &resolveURI)
+			const std::function<std::string(const std::string &uri)> &resolveURI,
+			std::optional<std::string> &&glbData = std::nullopt)
 		: byteLength(as<std::size_t>(o["byteLength"]))
 	{
 		check(o.isObject());
@@ -468,6 +471,13 @@ struct Buffer {
 		if (o.isMember("name")) {
 			name = as<std::string>(o["name"]);
 		}
+		if (glbData.has_value()) {
+			check(!o.isMember("uri"));
+			data = *std::move(glbData);
+			// GLB allows padding, which need not be reflected in the JSON
+			check(byteLength + 3 >= data.size());
+			check(data.size() >= byteLength);
+		} else {
 			check(o.isMember("uri"));
 			bool dataURI = false;
 			const std::string uri = as<std::string>(o["uri"]);
@@ -486,6 +496,7 @@ struct Buffer {
 			if (!dataURI)
 				data = resolveURI(uri);
 			check(data.size() >= byteLength);
+		}
 		data.resize(byteLength);
 	}
 };
@@ -1093,6 +1104,12 @@ struct Texture {
 };
 template<> Texture as(const Json::Value &o) { return o; }
 
+using UriResolver = std::function<std::string(const std::string &uri)>;
+static std::string uriError(const std::string &uri) {
+	// only base64 data URI support by default
+	throw std::runtime_error("unsupported URI: " + uri);
+}
+
 struct GlTF {
 	std::optional<std::vector<Accessor>> accessors;
 	std::optional<std::vector<Animation>> animations;
@@ -1111,12 +1128,10 @@ struct GlTF {
 	std::optional<std::vector<Scene>> scenes;
 	std::optional<std::vector<Skin>> skins;
 	std::optional<std::vector<Texture>> textures;
-	static std::string uriError(const std::string &uri) {
-		// only base64 data URI support by default
-		throw std::runtime_error("unsupported URI: " + uri);
-	}
+
 	GlTF(const Json::Value &o,
-			const std::function<std::string(const std::string &uri)> &resolveURI = uriError)
+			const UriResolver &resolveUri = uriError,
+			std::optional<std::string> &&glbData = std::nullopt)
 		: asset(as<Asset>(o["asset"]))
 	{
 		check(o.isObject());
@@ -1138,7 +1153,8 @@ struct GlTF {
 			std::vector<Buffer> bufs;
 			bufs.reserve(b.size());
 			for (Json::ArrayIndex i = 0; i < b.size(); ++i) {
-				bufs.emplace_back(b[i], resolveURI);
+				bufs.emplace_back(b[i], resolveUri,
+						i == 0 ? std::move(glbData) : std::nullopt);
 			}
 			check(bufs.size() >= 1);
 			buffers = std::move(bufs);
@@ -1354,4 +1370,123 @@ struct GlTF {
 	}
 };
 
+// std::span is C++ 20, so we roll our own little struct here.
+template <typename T>
+struct Span {
+	T *ptr;
+	uint32_t len;
+	bool empty() const {
+		return len == 0;
+	}
+	T *end() const {
+		return ptr + len;
+	}
+	template <typename U>
+	Span<U> cast() const {
+		return {(U *) ptr, len};
+	}
+};
+
+static Json::Value readJson(Span<const char> span) {
+	Json::CharReaderBuilder builder;
+	const std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
+	Json::Value json;
+	JSONCPP_STRING err;
+	if (!reader->parse(span.ptr, span.end(), &json, &err))
+		throw std::runtime_error("invalid JSON");
+	return json;
+}
+
+inline GlTF readGlb(const char *data, std::size_t len, const UriResolver &resolveUri = uriError) {
+	struct Chunk {
+		uint32_t type;
+		Span<const uint8_t> span;
+	};
+
+	struct Stream {
+		Span<const uint8_t> span;
+
+		bool eof() const {
+			return span.empty();
+		}
+
+		void advance(uint32_t n) {
+			span.len -= n;
+			span.ptr += n;
+		}
+
+		uint32_t readUint32() {
+			if (span.len < 4)
+				throw std::runtime_error("premature EOF");
+			uint32_t res = 0;
+			for (int i = 0; i < 4; ++i)
+				res += span.ptr[i] << (i * 8);
+			advance(4);
+			return res;
+		}
+
+		Chunk readChunk() {
+			const auto chunkLen = readUint32();
+			if (chunkLen % 4 != 0)
+				throw std::runtime_error("chunk length must be multiple of 4");
+			const auto chunkType = readUint32();
+
+			auto chunkPtr = span.ptr;
+			if (span.len < chunkLen)
+				throw std::runtime_error("premature EOF");
+			advance(chunkLen);
+			return {chunkType, {chunkPtr, chunkLen}};
+		}
+	};
+
+	constexpr uint32_t MAGIC_glTF = 0x46546C67;
+	constexpr uint32_t MAGIC_JSON = 0x4E4F534A;
+	constexpr uint32_t MAGIC_BIN = 0x004E4942;
+
+	if (len > std::numeric_limits<uint32_t>::max())
+		throw std::runtime_error("too large");
+
+	Stream is{{(const uint8_t *) data, static_cast<uint32_t>(len)}};
+
+	const auto magic = is.readUint32();
+	if (magic != MAGIC_glTF) // glTF
+		throw std::runtime_error("wrong magic number");
+	const auto version = is.readUint32();
+	if (version != 2)
+		throw std::runtime_error("wrong version");
+	const auto length = is.readUint32();
+	if (length != len)
+		throw std::runtime_error("wrong length");
+
+	const auto json = is.readChunk();
+	if (json.type != MAGIC_JSON)
+		throw std::runtime_error("expected JSON chunk");
+
+	std::optional<std::string> buffer;
+	if (!is.eof()) {
+		const auto chunk = is.readChunk();
+		if (chunk.type == MAGIC_BIN)
+			buffer = std::string((const char *) chunk.span.ptr, chunk.span.len);
+		else if (chunk.type == MAGIC_JSON)
+			throw std::runtime_error("unexpected chunk");
+		// Ignore all other chunks. We still want to validate that
+		// 1. These chunks are valid;
+		// 2. These chunks are *not* JSON or BIN chunks
+		while (!is.eof()) {
+			const auto type = is.readChunk().type;
+			if (type == MAGIC_JSON || type == MAGIC_BIN)
+				throw std::runtime_error("unexpected chunk");
+		}
+	}
+
+	return GlTF(readJson(json.span.cast<const char>()), resolveUri, std::move(buffer));
+}
+
+inline GlTF readGlTF(const char *data, std::size_t len, const UriResolver &resolveUri = uriError) {
+	if (len > std::numeric_limits<uint32_t>::max())
+		throw std::runtime_error("too large");
+
+	return GlTF(readJson({data, static_cast<uint32_t>(len)}), resolveUri);
+}
+
 }

src/client/client.cpp

@@ -827,7 +827,7 @@ bool Client::loadMedia(const std::string &data, const std::string &filename,
 	}
 
 	const char *model_ext[] = {
-		".x", ".b3d", ".obj", ".gltf",
+		".x", ".b3d", ".obj", ".gltf", ".glb",
 		NULL
 	};
 	name = removeStringEnd(filename, model_ext);

src/server.cpp

@@ -2465,7 +2465,7 @@ bool Server::addMediaFile(const std::string &filename,
 	const char *supported_ext[] = {
 		".png", ".jpg", ".bmp", ".tga",
 		".ogg",
-		".x", ".b3d", ".obj", ".gltf",
+		".x", ".b3d", ".obj", ".gltf", ".glb",
 		// Custom translation file format
 		".tr",
 		NULL

src/unittest/test_irr_gltf_mesh_loader.cpp

@@ -82,7 +82,10 @@ SECTION("minimal triangle") {
 }
 
 SECTION("blender cube") {
-	const auto mesh = loadMesh(model_stem + "blender_cube.gltf");
+	const auto path = GENERATE(
+		model_stem + "blender_cube.gltf",
+		model_stem + "blender_cube.glb");
+	const auto mesh = loadMesh(path);
 	REQUIRE(mesh != nullptr);
 	REQUIRE(mesh->getMeshBufferCount() == 1);
 	SECTION("vertex coordinates are correct") {