Files
XCEngine/MVS/3DGS-Unity/Editor/Utils/PLYFileReader.cs
2026-03-29 01:36:53 +08:00

108 lines
4.1 KiB
C#

// SPDX-License-Identifier: MIT
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using Unity.Collections;
namespace GaussianSplatting.Editor.Utils
{
public static class PLYFileReader
{
public static void ReadFileHeader(string filePath, out int vertexCount, out int vertexStride, out List<string> attrNames)
{
vertexCount = 0;
vertexStride = 0;
attrNames = new List<string>();
if (!File.Exists(filePath))
return;
using var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
ReadHeaderImpl(filePath, out vertexCount, out vertexStride, out attrNames, fs);
}
static void ReadHeaderImpl(string filePath, out int vertexCount, out int vertexStride, out List<string> attrNames, FileStream fs)
{
// C# arrays and NativeArrays make it hard to have a "byte" array larger than 2GB :/
if (fs.Length >= 2 * 1024 * 1024 * 1024L)
throw new IOException($"PLY {filePath} read error: currently files larger than 2GB are not supported");
// read header
vertexCount = 0;
vertexStride = 0;
attrNames = new List<string>();
const int kMaxHeaderLines = 9000;
for (int lineIdx = 0; lineIdx < kMaxHeaderLines; ++lineIdx)
{
var line = ReadLine(fs);
if (line == "end_header" || line.Length == 0)
break;
var tokens = line.Split(' ');
if (tokens.Length == 3 && tokens[0] == "element" && tokens[1] == "vertex")
vertexCount = int.Parse(tokens[2]);
if (tokens.Length == 3 && tokens[0] == "property")
{
ElementType type = tokens[1] switch
{
"float" => ElementType.Float,
"double" => ElementType.Double,
"uchar" => ElementType.UChar,
_ => ElementType.None
};
vertexStride += TypeToSize(type);
attrNames.Add(tokens[2]);
}
}
//Debug.Log($"PLY {filePath} vtx {vertexCount} stride {vertexStride} attrs #{attrNames.Count} {string.Join(',', attrNames)}");
}
public static void ReadFile(string filePath, out int vertexCount, out int vertexStride, out List<string> attrNames, out NativeArray<byte> vertices)
{
using var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
ReadHeaderImpl(filePath, out vertexCount, out vertexStride, out attrNames, fs);
vertices = new NativeArray<byte>(vertexCount * vertexStride, Allocator.Persistent);
var readBytes = fs.Read(vertices);
if (readBytes != vertices.Length)
throw new IOException($"PLY {filePath} read error, expected {vertices.Length} data bytes got {readBytes}");
}
enum ElementType
{
None,
Float,
Double,
UChar
}
static int TypeToSize(ElementType t)
{
return t switch
{
ElementType.None => 0,
ElementType.Float => 4,
ElementType.Double => 8,
ElementType.UChar => 1,
_ => throw new ArgumentOutOfRangeException(nameof(t), t, null)
};
}
static string ReadLine(FileStream fs)
{
var byteBuffer = new List<byte>();
while (true)
{
int b = fs.ReadByte();
if (b == -1 || b == '\n')
break;
byteBuffer.Add((byte)b);
}
// if line had CRLF line endings, remove the CR part
if (byteBuffer.Count > 0 && byteBuffer.Last() == '\r')
byteBuffer.RemoveAt(byteBuffer.Count-1);
return Encoding.UTF8.GetString(byteBuffer.ToArray());
}
}
}