From 70e520eaf2fc61a3b889b4dae4acf16c2f76a170 Mon Sep 17 00:00:00 2001
From: Riyyi <riyyi3@gmail.com>
Date: Thu, 4 Feb 2021 11:50:03 +0100
Subject: [PATCH] Add gltf file class

---
 inferno/src/inferno/io/file.cpp     |   4 +-
 inferno/src/inferno/io/gltffile.cpp | 100 ++++++++++++++++++++++++++++
 inferno/src/inferno/io/gltffile.h   |  22 ++++++
 3 files changed, 124 insertions(+), 2 deletions(-)
 create mode 100644 inferno/src/inferno/io/gltffile.cpp
 create mode 100644 inferno/src/inferno/io/gltffile.h

diff --git a/inferno/src/inferno/io/file.cpp b/inferno/src/inferno/io/file.cpp
index 74b8ebb..9b39e89 100644
--- a/inferno/src/inferno/io/file.cpp
+++ b/inferno/src/inferno/io/file.cpp
@@ -1,5 +1,5 @@
-#include <iostream> // std::ios
-#include <memory>   // std::make_unique
+#include <ios>    // std::ios
+#include <memory> // std::make_unique
 
 #include "inferno/assert.h"
 #include "inferno/io/file.h"
diff --git a/inferno/src/inferno/io/gltffile.cpp b/inferno/src/inferno/io/gltffile.cpp
new file mode 100644
index 0000000..9e93e05
--- /dev/null
+++ b/inferno/src/inferno/io/gltffile.cpp
@@ -0,0 +1,100 @@
+#include <cstring> // strcmp ??
+#include <fstream> // std::ifstream
+#include <ios>     // std::ios
+
+#include "inferno/assert.h"
+#include "inferno/io/file.h"
+#include "inferno/io/gltffile.h"
+#include "inferno/io/log.h"
+#include "inferno/util/string.h"
+
+namespace Inferno {
+
+	std::pair<std::shared_ptr<char[]>, std::shared_ptr<char[]>> GlTFFile::read(const std::string& path)
+	{
+		std::string extension = path.substr(path.find_first_of("."));
+
+		if (extension.compare(".glb") == 0) {
+			return glb(path);
+		}
+		else if (extension.compare(".gltf") == 0) {
+			ASSERT_NOT_REACHED();
+		}
+
+		return {};
+	}
+
+	std::pair<std::shared_ptr<char[]>, std::shared_ptr<char[]>> GlTFFile::glb(const std::string& path)
+	{
+		// Create input stream object and open file
+		std::ifstream glb(path, std::ios::in | std::ios::binary);
+		ASSERT(glb.is_open(), "GlTFFile could not open '{}'", path);
+
+		constexpr uint32_t size = 4;
+		constexpr uint32_t header = 12;
+		constexpr uint32_t json = 27; // Minimum valid glTF has an asset property with version specifier
+
+		// Get the actual length of the file
+		uint32_t length = static_cast<uint32_t>(File::length(path, glb));
+		ASSERT(length > header + json, "GlTFFile too small to be valid '{}'", path);
+
+		// Read header
+
+		char magic[size];
+		char version[size];
+		char fileLength[size];
+
+		glb.read(magic, size);
+		glb.seekg(size * 1);
+		glb.read(version, size);
+		glb.seekg(size * 2);
+		glb.read(fileLength, size);
+
+		// Validate header
+
+		uint32_t magicInt = *reinterpret_cast<uint32_t*>(magic);
+		ASSERT(magicInt == 0x46546c67, "GlTF invalid header magic '{}'", magic);
+
+		uint32_t versionInt = *reinterpret_cast<uint32_t*>(version);
+		ASSERT(versionInt == 2, "GlTF unsupported version '{}'", versionInt);
+
+		uint32_t fileLengthInt = *reinterpret_cast<uint32_t*>(fileLength);
+		ASSERT(fileLengthInt == length, "GlTF file and reported byte size mismatch '{}' '{}'", length, fileLengthInt);
+
+		// Read JSON data
+		auto jsonChunk = readChunk(glb, header, 0x4e4f534a);
+
+		// Read binary data
+		auto binaryChunk = readChunk(glb, header + size * 2 + jsonChunk.second, 0x004e4942);
+
+		glb.close();
+
+		return { jsonChunk.first, binaryChunk.first };
+	}
+
+	std::pair<std::shared_ptr<char[]>, uint32_t> GlTFFile::readChunk(std::ifstream& ifstream, uint32_t offset, uint32_t type)
+	{
+		constexpr uint32_t size = 4;
+
+		char chunkLength[size];
+		char chunkType[size];
+
+		ifstream.seekg(offset);
+		ifstream.read(chunkLength, size);
+		ifstream.seekg(offset + size * 1);
+		ifstream.read(chunkType, size);
+
+		uint32_t chunkTypeInt = *reinterpret_cast<uint32_t*>(chunkType);
+		ASSERT(chunkTypeInt == type, "GlTF invalid chunk type '{}' != '{}'", chunkType, intToHex(type));
+
+		uint32_t chunkLengthInt = *reinterpret_cast<uint32_t*>(chunkLength);
+		// Allocate memory filled with zeros
+		std::shared_ptr<char[]> chunkData(new char[chunkLengthInt + 1]);
+		ifstream.seekg(offset + size * 2);
+		ifstream.read(chunkData.get(), chunkLengthInt);
+		chunkData.get()[chunkLengthInt] = '\0';
+
+		return { chunkData, chunkLengthInt };
+	}
+
+} // namespace Inferno
diff --git a/inferno/src/inferno/io/gltffile.h b/inferno/src/inferno/io/gltffile.h
new file mode 100644
index 0000000..b33ddd7
--- /dev/null
+++ b/inferno/src/inferno/io/gltffile.h
@@ -0,0 +1,22 @@
+#ifndef GLTF_FILE_H
+#define GLTF_FILE_H
+
+#include <cstdint> // uint32_t
+#include <memory>  // std::shared_ptr
+#include <string>  // std::string
+#include <utility> // std::pair
+
+namespace Inferno {
+
+	class GlTFFile {
+	public:
+		static std::pair<std::shared_ptr<char[]>, std::shared_ptr<char[]>> read(const std::string& path);
+
+	private:
+		static std::pair<std::shared_ptr<char[]>, std::shared_ptr<char[]>> glb(const std::string& path);
+		static std::pair<std::shared_ptr<char[]>, uint32_t> readChunk(std::ifstream& ifstream, uint32_t offset, uint32_t type);
+	};
+
+} // namespace Inferno
+
+#endif // GLTF_FILE_H