Clearer error message for non-binary LE PLY files (#165)

Author: aras-p

package/Editor/GaussianSplatAssetCreator.cs

@@ -87,7 +87,17 @@ void OnGUI()
 
             if (m_InputFile != m_PrevFilePath && !string.IsNullOrWhiteSpace(m_InputFile))
             {
-                m_PrevVertexCount = GaussianFileReader.ReadFileHeader(m_InputFile);
+                m_PrevVertexCount = 0;
+                m_ErrorMessage = null;
+                try
+                {
+                    m_PrevVertexCount = GaussianFileReader.ReadFileHeader(m_InputFile);
+                }
+                catch (Exception ex)
+                {
+                    m_ErrorMessage = ex.Message;
+                }
+
                 m_PrevFileSize = File.Exists(m_InputFile) ? new FileInfo(m_InputFile).Length : 0;
                 m_PrevFilePath = m_InputFile;
             }

package/Editor/Utils/PLYFileReader.cs

@@ -33,12 +33,15 @@ static void ReadHeaderImpl(string filePath, out int vertexCount, out int vertexS
             vertexStride = 0;
             attrs = new List<(string, ElementType)>();
             const int kMaxHeaderLines = 9000;
+            bool got_binary_le = false;
             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] == "format" && tokens[1] == "binary_little_endian" && tokens[2] == "1.0")
+                    got_binary_le = true;
                 if (tokens.Length == 3 && tokens[0] == "element" && tokens[1] == "vertex")
                     vertexCount = int.Parse(tokens[2]);
                 if (tokens.Length == 3 && tokens[0] == "property")
@@ -54,6 +57,11 @@ static void ReadHeaderImpl(string filePath, out int vertexCount, out int vertexS
                     attrs.Add((tokens[2], type));
                 }
             }
+
+            if (!got_binary_le)
+            {
+                throw new IOException($"PLY {filePath} not supported: needs to be binary, little endian PLY format");
+            }
         }
 
         public static void ReadFile(string filePath, out int vertexCount, out int vertexStride, out List<(string, ElementType)> attrs, out NativeArray<byte> vertices)