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# glbフォーマット概説
JSON記述部と、画像や頂点配列を記録するバイナリ部の２つの部分からなります。
gltf形式では、URLやパスで参照する方法で外部のバイナリデータにアクセスします。
glb形式ではJSON部とバイナリ部をひとつのファイルにまとめていて、バイト列のオフセットでバイナリデータにアクセスします。
プログラムから扱うには外部ファイルへのアクセスが無いglb形式の方が簡単[^VRM_glb]です。
[^VRM_glb]: VRMではglbを採用しています。
## glb形式
``ヘッダ部 + チャンク部繰り返し``という構造になっています。
実質的には、
``ヘッダ部 + JSON CHUNk + BINARY CHUNK``となります。
ヘッダ部
| 長さ | 内容 | 型 | 値 |
|:-----|:---------------|:------|:-------|
| 4 | | ascii | "glTF" |
| 4 | gltfバージョン | int32 | 2 |
| 4 | file size | int32 | |
チャンク部
| 長さ | 内容 | 型 | 値 |
|:-----------|:-----------|:---------|:--------------------|
| 4 | chunk size | int32 | |
| 4 | chunk type | ascii | "JSON" or "BIN\x00" |
| chunk size | chunk body | バイト列 | |
### python3によるパース例
```python
import struct
import json
class Reader:
def __init__(self, data: bytes)->None:
self.data = data
self.pos = 0
def read_str(self, size):
result = self.data[self.pos: self.pos + size]
self.pos += size
return result.strip()
def read(self, size):
result = self.data[self.pos: self.pos + size]
self.pos += size
return result
def read_uint(self):
result = struct.unpack('I', self.data[self.pos:self.pos + 4])[0]
self.pos += 4
return result
def parse_glb(data: bytes):
reader = Reader(data)
magic = reader.read_str(4)
if magic != b'glTF':
raise Exception(f'magic not found: #{magic}')
version = reader.read_uint()
if version != 2:
raise Exception(f'version:#{version} is not 2')
size = reader.read_uint()
size -= 12
json_str = None
body = None
while size > 0:
#print(size)
chunk_size = reader.read_uint()
size -= 4
chunk_type = reader.read_str(4)
size -= 4
chunk_data = reader.read(chunk_size)
size -= chunk_size
if chunk_type == b'BIN\x00':
body = chunk_data
elif chunk_type == b'JSON':
json_str = chunk_data
else:
raise Exception(f'unknown chunk_type: {chunk_type}')
return json.loads(json_str), body
with open('AliciaSolid.vrm', 'rb') as f:
parsed, body = parse_glb(f.read())
```

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gltf/0_82_glb_import
gltf/how_to_impl_extension
gltf/0_36_update
gltf/format
```
## VRM

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@@ -130,7 +130,7 @@
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<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" />
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<div class="document">
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<div class="body" role="main">
<section class="tex2jax_ignore mathjax_ignore" id="glb">
<h1>glbフォーマット概説<a class="headerlink" href="#glb" title="Permalink to this headline"></a></h1>
<p>JSON記述部と、画像や頂点配列を記録するバイナリ部の２つの部分からなります。</p>
<p>gltf形式では、URLやパスで参照する方法で外部のバイナリデータにアクセスします。
glb形式ではJSON部とバイナリ部をひとつのファイルにまとめていて、バイト列のオフセットでバイナリデータにアクセスします。
プログラムから扱うには外部ファイルへのアクセスが無いglb形式の方が簡単<a class="footnote-reference brackets" href="#vrm-glb" id="id1">1</a>です。</p>
<section id="id2">
<h2>glb形式<a class="headerlink" href="#id2" title="Permalink to this headline"></a></h2>
<p><code class="docutils literal notranslate"><span class="pre">ヘッダ部</span> <span class="pre">+</span> <span class="pre">チャンク部繰り返し</span></code>という構造になっています。
実質的には、
<code class="docutils literal notranslate"><span class="pre">ヘッダ部</span> <span class="pre">+</span> <span class="pre">JSON</span> <span class="pre">CHUNk</span> <span class="pre">+</span> <span class="pre">BINARY</span> <span class="pre">CHUNK</span></code>となります。</p>
<p>ヘッダ部</p>
<table class="colwidths-auto docutils align-default">
<thead>
<tr class="row-odd"><th class="text-align:left head"><p>長さ</p></th>
<th class="text-align:left head"><p>内容</p></th>
<th class="text-align:left head"><p>型</p></th>
<th class="text-align:left head"><p>値</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p></p></td>
<td class="text-align:left"><p>ascii</p></td>
<td class="text-align:left"><p>“glTF”</p></td>
</tr>
<tr class="row-odd"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>gltfバージョン</p></td>
<td class="text-align:left"><p>int32</p></td>
<td class="text-align:left"><p>2</p></td>
</tr>
<tr class="row-even"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>file size</p></td>
<td class="text-align:left"><p>int32</p></td>
<td class="text-align:left"><p></p></td>
</tr>
</tbody>
</table>
<p>チャンク部</p>
<table class="colwidths-auto docutils align-default">
<thead>
<tr class="row-odd"><th class="text-align:left head"><p>長さ</p></th>
<th class="text-align:left head"><p>内容</p></th>
<th class="text-align:left head"><p>型</p></th>
<th class="text-align:left head"><p>値</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>chunk size</p></td>
<td class="text-align:left"><p>int32</p></td>
<td class="text-align:left"><p></p></td>
</tr>
<tr class="row-odd"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>chunk type</p></td>
<td class="text-align:left"><p>ascii</p></td>
<td class="text-align:left"><p>“JSON” or “BIN\x00”</p></td>
</tr>
<tr class="row-even"><td class="text-align:left"><p>chunk size</p></td>
<td class="text-align:left"><p>chunk body</p></td>
<td class="text-align:left"><p>バイト列</p></td>
<td class="text-align:left"><p></p></td>
</tr>
</tbody>
</table>
<section id="python3">
<h3>python3によるパース例<a class="headerlink" href="#python3" title="Permalink to this headline"></a></h3>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">struct</span>
<span class="kn">import</span> <span class="nn">json</span>
<span class="k">class</span> <span class="nc">Reader</span><span class="p">:</span>
<span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">data</span><span class="p">:</span> <span class="nb">bytes</span><span class="p">)</span><span class="o">-&gt;</span><span class="bp">None</span><span class="p">:</span>
<span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="n">data</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">=</span> <span class="mi">0</span>
<span class="k">def</span> <span class="nf">read_str</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">size</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+</span> <span class="n">size</span><span class="p">]</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+=</span> <span class="n">size</span>
<span class="k">return</span> <span class="n">result</span><span class="o">.</span><span class="n">strip</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">read</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">size</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+</span> <span class="n">size</span><span class="p">]</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+=</span> <span class="n">size</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">def</span> <span class="nf">read_uint</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="n">struct</span><span class="o">.</span><span class="n">unpack</span><span class="p">(</span><span class="s1">&#39;I&#39;</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span><span class="p">:</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+</span> <span class="mi">4</span><span class="p">])[</span><span class="mi">0</span><span class="p">]</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+=</span> <span class="mi">4</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">def</span> <span class="nf">parse_glb</span><span class="p">(</span><span class="n">data</span><span class="p">:</span> <span class="nb">bytes</span><span class="p">):</span>
<span class="n">reader</span> <span class="o">=</span> <span class="n">Reader</span><span class="p">(</span><span class="n">data</span><span class="p">)</span>
<span class="n">magic</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_str</span><span class="p">(</span><span class="mi">4</span><span class="p">)</span>
<span class="k">if</span> <span class="n">magic</span> <span class="o">!=</span> <span class="sa">b</span><span class="s1">&#39;glTF&#39;</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="n">f</span><span class="s1">&#39;magic not found: #{magic}&#39;</span><span class="p">)</span>
<span class="n">version</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_uint</span><span class="p">()</span>
<span class="k">if</span> <span class="n">version</span> <span class="o">!=</span> <span class="mi">2</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="n">f</span><span class="s1">&#39;version:#{version} is not 2&#39;</span><span class="p">)</span>
<span class="n">size</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_uint</span><span class="p">()</span>
<span class="n">size</span> <span class="o">-=</span> <span class="mi">12</span>
<span class="n">json_str</span> <span class="o">=</span> <span class="bp">None</span>
<span class="n">body</span> <span class="o">=</span> <span class="bp">None</span>
<span class="k">while</span> <span class="n">size</span> <span class="o">&gt;</span> <span class="mi">0</span><span class="p">:</span>
<span class="c1">#print(size)</span>
<span class="n">chunk_size</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_uint</span><span class="p">()</span>
<span class="n">size</span> <span class="o">-=</span> <span class="mi">4</span>
<span class="n">chunk_type</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_str</span><span class="p">(</span><span class="mi">4</span><span class="p">)</span>
<span class="n">size</span> <span class="o">-=</span> <span class="mi">4</span>
<span class="n">chunk_data</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read</span><span class="p">(</span><span class="n">chunk_size</span><span class="p">)</span>
<span class="n">size</span> <span class="o">-=</span> <span class="n">chunk_size</span>
<span class="k">if</span> <span class="n">chunk_type</span> <span class="o">==</span> <span class="sa">b</span><span class="s1">&#39;BIN</span><span class="se">\x00</span><span class="s1">&#39;</span><span class="p">:</span>
<span class="n">body</span> <span class="o">=</span> <span class="n">chunk_data</span>
<span class="k">elif</span> <span class="n">chunk_type</span> <span class="o">==</span> <span class="sa">b</span><span class="s1">&#39;JSON&#39;</span><span class="p">:</span>
<span class="n">json_str</span> <span class="o">=</span> <span class="n">chunk_data</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="n">f</span><span class="s1">&#39;unknown chunk_type: {chunk_type}&#39;</span><span class="p">)</span>
<span class="k">return</span> <span class="n">json</span><span class="o">.</span><span class="n">loads</span><span class="p">(</span><span class="n">json_str</span><span class="p">),</span> <span class="n">body</span>
<span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">&#39;AliciaSolid.vrm&#39;</span><span class="p">,</span> <span class="s1">&#39;rb&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
<span class="n">parsed</span><span class="p">,</span> <span class="n">body</span> <span class="o">=</span> <span class="n">parse_glb</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">())</span>
</pre></div>
</div>
<hr class="footnotes docutils" />
<dl class="footnote brackets">
<dt class="label" id="vrm-glb"><span class="brackets"><a class="fn-backref" href="#id1">1</a></span></dt>
<dd><p>VRMではglbを採用しています。</p>
</dd>
</dl>
</section>
</section>
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<li class="toctree-l1"><a class="reference internal" href="gltf/0_82_glb_import.html">GlbImport(0.82)</a></li>
<li class="toctree-l1"><a class="reference internal" href="gltf/how_to_impl_extension.html">The implementation of glTF extensions(0.63.2)</a></li>
<li class="toctree-l1"><a class="reference internal" href="gltf/0_36_update.html">GltfUpdate(0.36)</a></li>
<li class="toctree-l1"><a class="reference internal" href="gltf/format.html">glbフォーマット概説</a></li>
</ul>
</div>
</section>

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<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
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@@ -28,7 +28,7 @@
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accesskey="N">next</a> |</li>
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@@ -147,8 +147,8 @@
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<h4>Previous topic</h4>
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title="previous chapter">GltfUpdate(0.36)</a></p>
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<h4>Next topic</h4>
<p class="topless"><a href="0_79_runtime_import.html"
title="next chapter">RuntimeImport(0.79)</a></p>
@@ -183,7 +183,7 @@
<a href="0_79_runtime_import.html" title="RuntimeImport(0.79)"
>next</a> |</li>
<li class="right" >
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# glbフォーマット概説
JSON記述部と、画像や頂点配列を記録するバイナリ部の２つの部分からなります。
gltf形式では、URLやパスで参照する方法で外部のバイナリデータにアクセスします。
glb形式ではJSON部とバイナリ部をひとつのファイルにまとめていて、バイト列のオフセットでバイナリデータにアクセスします。
プログラムから扱うには外部ファイルへのアクセスが無いglb形式の方が簡単[^VRM_glb]です。
[^VRM_glb]: VRMではglbを採用しています。
## glb形式
``ヘッダ部 + チャンク部繰り返し``という構造になっています。
実質的には、
``ヘッダ部 + JSON CHUNk + BINARY CHUNK``となります。
ヘッダ部
| 長さ | 内容 | 型 | 値 |
|:-----|:---------------|:------|:-------|
| 4 | | ascii | "glTF" |
| 4 | gltfバージョン | int32 | 2 |
| 4 | file size | int32 | |
チャンク部
| 長さ | 内容 | 型 | 値 |
|:-----------|:-----------|:---------|:--------------------|
| 4 | chunk size | int32 | |
| 4 | chunk type | ascii | "JSON" or "BIN\x00" |
| chunk size | chunk body | バイト列 | |
### python3によるパース例
```python
import struct
import json
class Reader:
def __init__(self, data: bytes)->None:
self.data = data
self.pos = 0
def read_str(self, size):
result = self.data[self.pos: self.pos + size]
self.pos += size
return result.strip()
def read(self, size):
result = self.data[self.pos: self.pos + size]
self.pos += size
return result
def read_uint(self):
result = struct.unpack('I', self.data[self.pos:self.pos + 4])[0]
self.pos += 4
return result
def parse_glb(data: bytes):
reader = Reader(data)
magic = reader.read_str(4)
if magic != b'glTF':
raise Exception(f'magic not found: #{magic}')
version = reader.read_uint()
if version != 2:
raise Exception(f'version:#{version} is not 2')
size = reader.read_uint()
size -= 12
json_str = None
body = None
while size > 0:
#print(size)
chunk_size = reader.read_uint()
size -= 4
chunk_type = reader.read_str(4)
size -= 4
chunk_data = reader.read(chunk_size)
size -= chunk_size
if chunk_type == b'BIN\x00':
body = chunk_data
elif chunk_type == b'JSON':
json_str = chunk_data
else:
raise Exception(f'unknown chunk_type: {chunk_type}')
return json.loads(json_str), body
with open('AliciaSolid.vrm', 'rb') as f:
parsed, body = parse_glb(f.read())
```

1
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@@ -29,6 +29,7 @@ build
gltf/0_82_glb_import
gltf/how_to_impl_extension
gltf/0_36_update
gltf/format
```
## VRM

10
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@@ -16,7 +16,7 @@
<script src="../_static/translations.js"></script>
<link rel="index" title="索引" href="../genindex.html" />
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@@ -26,7 +26,7 @@
<a href="../genindex.html" title="総合索引"
accesskey="I">索引</a></li>
<li class="right" >
<a href="../vrm0/0_82_runtime_import.html" title="RuntimeImport(0.82)"
<a href="format.html" title="glbフォーマット概説"
accesskey="N">次へ</a> |</li>
<li class="right" >
<a href="how_to_impl_extension.html" title="glTF拡張の実装(0.63.2)"
@@ -101,8 +101,8 @@
<p class="topless"><a href="how_to_impl_extension.html"
title="前の章へ">glTF拡張の実装(0.63.2)</a></p>
<h4>次のトピックへ</h4>
<p class="topless"><a href="../vrm0/0_82_runtime_import.html"
title="次の章へ">RuntimeImport(0.82)</a></p>
<p class="topless"><a href="format.html"
title="次の章へ">glbフォーマット概説</a></p>
<div role="note" aria-label="source link">
<h3>このページ</h3>
<ul class="this-page-menu">
@@ -131,7 +131,7 @@
<a href="../genindex.html" title="総合索引"
>索引</a></li>
<li class="right" >
<a href="../vrm0/0_82_runtime_import.html" title="RuntimeImport(0.82)"
<a href="format.html" title="glbフォーマット概説"
>次へ</a> |</li>
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@@ -0,0 +1,257 @@
<!DOCTYPE html>
<html lang="ja">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" />
<title>glbフォーマット概説 &#8212; UniVRM Programming Document ドキュメント</title>
<link rel="stylesheet" type="text/css" href="../_static/pygments.css" />
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<h3>ナビゲーション</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="総合索引"
accesskey="I">索引</a></li>
<li class="right" >
<a href="../vrm0/0_82_runtime_import.html" title="RuntimeImport(0.82)"
accesskey="N">次へ</a> |</li>
<li class="right" >
<a href="0_36_update.html" title="GltfUpdate(0.36)"
accesskey="P">前へ</a> |</li>
<li class="nav-item nav-item-0"><a href="../index.html">UniVRM Programming Document ドキュメント</a> &#187;</li>
<li class="nav-item nav-item-this"><a href="">glbフォーマット概説</a></li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<section class="tex2jax_ignore mathjax_ignore" id="glb">
<h1>glbフォーマット概説<a class="headerlink" href="#glb" title="このヘッドラインへのパーマリンク"></a></h1>
<p>JSON記述部と、画像や頂点配列を記録するバイナリ部の２つの部分からなります。</p>
<p>gltf形式では、URLやパスで参照する方法で外部のバイナリデータにアクセスします。
glb形式ではJSON部とバイナリ部をひとつのファイルにまとめていて、バイト列のオフセットでバイナリデータにアクセスします。
プログラムから扱うには外部ファイルへのアクセスが無いglb形式の方が簡単<a class="footnote-reference brackets" href="#vrm-glb" id="id1">1</a>です。</p>
<section id="id2">
<h2>glb形式<a class="headerlink" href="#id2" title="このヘッドラインへのパーマリンク"></a></h2>
<p><code class="docutils literal notranslate"><span class="pre">ヘッダ部</span> <span class="pre">+</span> <span class="pre">チャンク部繰り返し</span></code>という構造になっています。
実質的には、
<code class="docutils literal notranslate"><span class="pre">ヘッダ部</span> <span class="pre">+</span> <span class="pre">JSON</span> <span class="pre">CHUNk</span> <span class="pre">+</span> <span class="pre">BINARY</span> <span class="pre">CHUNK</span></code>となります。</p>
<p>ヘッダ部</p>
<table class="colwidths-auto docutils align-default">
<thead>
<tr class="row-odd"><th class="text-align:left head"><p>長さ</p></th>
<th class="text-align:left head"><p>内容</p></th>
<th class="text-align:left head"><p>型</p></th>
<th class="text-align:left head"><p>値</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p></p></td>
<td class="text-align:left"><p>ascii</p></td>
<td class="text-align:left"><p>&quot;glTF&quot;</p></td>
</tr>
<tr class="row-odd"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>gltfバージョン</p></td>
<td class="text-align:left"><p>int32</p></td>
<td class="text-align:left"><p>2</p></td>
</tr>
<tr class="row-even"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>file size</p></td>
<td class="text-align:left"><p>int32</p></td>
<td class="text-align:left"><p></p></td>
</tr>
</tbody>
</table>
<p>チャンク部</p>
<table class="colwidths-auto docutils align-default">
<thead>
<tr class="row-odd"><th class="text-align:left head"><p>長さ</p></th>
<th class="text-align:left head"><p>内容</p></th>
<th class="text-align:left head"><p>型</p></th>
<th class="text-align:left head"><p>値</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>chunk size</p></td>
<td class="text-align:left"><p>int32</p></td>
<td class="text-align:left"><p></p></td>
</tr>
<tr class="row-odd"><td class="text-align:left"><p>4</p></td>
<td class="text-align:left"><p>chunk type</p></td>
<td class="text-align:left"><p>ascii</p></td>
<td class="text-align:left"><p>&quot;JSON&quot; or &quot;BIN\x00&quot;</p></td>
</tr>
<tr class="row-even"><td class="text-align:left"><p>chunk size</p></td>
<td class="text-align:left"><p>chunk body</p></td>
<td class="text-align:left"><p>バイト列</p></td>
<td class="text-align:left"><p></p></td>
</tr>
</tbody>
</table>
<section id="python3">
<h3>python3によるパース例<a class="headerlink" href="#python3" title="このヘッドラインへのパーマリンク"></a></h3>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">struct</span>
<span class="kn">import</span> <span class="nn">json</span>
<span class="k">class</span> <span class="nc">Reader</span><span class="p">:</span>
<span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">data</span><span class="p">:</span> <span class="nb">bytes</span><span class="p">)</span><span class="o">-&gt;</span><span class="bp">None</span><span class="p">:</span>
<span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="n">data</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">=</span> <span class="mi">0</span>
<span class="k">def</span> <span class="nf">read_str</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">size</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+</span> <span class="n">size</span><span class="p">]</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+=</span> <span class="n">size</span>
<span class="k">return</span> <span class="n">result</span><span class="o">.</span><span class="n">strip</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">read</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">size</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+</span> <span class="n">size</span><span class="p">]</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+=</span> <span class="n">size</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">def</span> <span class="nf">read_uint</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">result</span> <span class="o">=</span> <span class="n">struct</span><span class="o">.</span><span class="n">unpack</span><span class="p">(</span><span class="s1">&#39;I&#39;</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span><span class="p">:</span><span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+</span> <span class="mi">4</span><span class="p">])[</span><span class="mi">0</span><span class="p">]</span>
<span class="bp">self</span><span class="o">.</span><span class="n">pos</span> <span class="o">+=</span> <span class="mi">4</span>
<span class="k">return</span> <span class="n">result</span>
<span class="k">def</span> <span class="nf">parse_glb</span><span class="p">(</span><span class="n">data</span><span class="p">:</span> <span class="nb">bytes</span><span class="p">):</span>
<span class="n">reader</span> <span class="o">=</span> <span class="n">Reader</span><span class="p">(</span><span class="n">data</span><span class="p">)</span>
<span class="n">magic</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_str</span><span class="p">(</span><span class="mi">4</span><span class="p">)</span>
<span class="k">if</span> <span class="n">magic</span> <span class="o">!=</span> <span class="sa">b</span><span class="s1">&#39;glTF&#39;</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="n">f</span><span class="s1">&#39;magic not found: #{magic}&#39;</span><span class="p">)</span>
<span class="n">version</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_uint</span><span class="p">()</span>
<span class="k">if</span> <span class="n">version</span> <span class="o">!=</span> <span class="mi">2</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="n">f</span><span class="s1">&#39;version:#{version} is not 2&#39;</span><span class="p">)</span>
<span class="n">size</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_uint</span><span class="p">()</span>
<span class="n">size</span> <span class="o">-=</span> <span class="mi">12</span>
<span class="n">json_str</span> <span class="o">=</span> <span class="bp">None</span>
<span class="n">body</span> <span class="o">=</span> <span class="bp">None</span>
<span class="k">while</span> <span class="n">size</span> <span class="o">&gt;</span> <span class="mi">0</span><span class="p">:</span>
<span class="c1">#print(size)</span>
<span class="n">chunk_size</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_uint</span><span class="p">()</span>
<span class="n">size</span> <span class="o">-=</span> <span class="mi">4</span>
<span class="n">chunk_type</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read_str</span><span class="p">(</span><span class="mi">4</span><span class="p">)</span>
<span class="n">size</span> <span class="o">-=</span> <span class="mi">4</span>
<span class="n">chunk_data</span> <span class="o">=</span> <span class="n">reader</span><span class="o">.</span><span class="n">read</span><span class="p">(</span><span class="n">chunk_size</span><span class="p">)</span>
<span class="n">size</span> <span class="o">-=</span> <span class="n">chunk_size</span>
<span class="k">if</span> <span class="n">chunk_type</span> <span class="o">==</span> <span class="sa">b</span><span class="s1">&#39;BIN</span><span class="se">\x00</span><span class="s1">&#39;</span><span class="p">:</span>
<span class="n">body</span> <span class="o">=</span> <span class="n">chunk_data</span>
<span class="k">elif</span> <span class="n">chunk_type</span> <span class="o">==</span> <span class="sa">b</span><span class="s1">&#39;JSON&#39;</span><span class="p">:</span>
<span class="n">json_str</span> <span class="o">=</span> <span class="n">chunk_data</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="n">f</span><span class="s1">&#39;unknown chunk_type: {chunk_type}&#39;</span><span class="p">)</span>
<span class="k">return</span> <span class="n">json</span><span class="o">.</span><span class="n">loads</span><span class="p">(</span><span class="n">json_str</span><span class="p">),</span> <span class="n">body</span>
<span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">&#39;AliciaSolid.vrm&#39;</span><span class="p">,</span> <span class="s1">&#39;rb&#39;</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
<span class="n">parsed</span><span class="p">,</span> <span class="n">body</span> <span class="o">=</span> <span class="n">parse_glb</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">())</span>
</pre></div>
</div>
<hr class="footnotes docutils" />
<dl class="footnote brackets">
<dt class="label" id="vrm-glb"><span class="brackets"><a class="fn-backref" href="#id1">1</a></span></dt>
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