Added some defensive checks when reading/writing to IO file stream. I…

…f a format (like OBJ) is distributed across multiple files, make a note in the Import/Convert from stream methods that a custiom IOSystem only works from Import/Convert from file.

Added a unit test to verify this. Refreshed docs

AssimpNet.Test/IOSystem_TestFixture.cs

@@ -73,5 +73,41 @@ public void TestIOSystemError()
                 importer.ImportFile(fileName, PostProcessSteps.None);
             });
         }
+
+        [Test]
+        public void TestIOSystem_ImportObj()
+        {
+            String dir = Path.Combine(TestHelper.RootPath, "TestFiles");
+            LogStream.IsVerboseLoggingEnabled = true;
+            ConsoleLogStream log = new ConsoleLogStream();
+            log.Attach();
+
+            using(AssimpContext importer = new AssimpContext())
+            {
+                FileIOSystem iOSystem = new FileIOSystem(dir);
+                importer.SetIOSystem(iOSystem);
+
+                //Using stream does not use the IO system...
+                using(Stream fs = File.OpenRead(Path.Combine(dir, "sphere.obj")))
+                {
+                    Scene scene = importer.ImportFileFromStream(fs, "obj");
+                    Assert.IsTrue(scene != null);
+                    Assert.IsTrue(scene.HasMeshes);
+                    Assert.IsTrue(scene.HasMaterials);
+
+                    //No material file, so the mesh will always use the default material
+                    Assert.IsTrue(scene.Materials[scene.Meshes[0].MaterialIndex].Name == "DefaultMaterial");
+                }
+
+                //Using custom IO system requires us to pass in the file name, assimp will ask the io system to get a stream
+                Scene scene2 = importer.ImportFile("sphere.obj");
+                Assert.IsTrue(scene2 != null);
+                Assert.IsTrue(scene2.HasMeshes);
+                Assert.IsTrue(scene2.HasMaterials);
+
+                //Should have found a material with the name "SphereMaterial" in the mtl file
+                Assert.IsTrue(scene2.Materials[scene2.Meshes[0].MaterialIndex].Name == "SphereMaterial");
+            }
+        }
     }
 }

AssimpNet.Test/TestFiles/sphere.mtl

@@ -1,6 +1,6 @@
 # Blender MTL File: 'sphere.blend'
 # Material Count: 1
-newmtl 
+newmtl SphereMaterial
 Ns 0
 Ka 0.000000 0.000000 0.000000
 Kd 0.8 0.8 0.8

AssimpNet.shfbproj

@@ -15,7 +15,7 @@
     <RootNamespace>Documentation</RootNamespace>
     <Name>Documentation</Name>
     <!-- SHFB properties -->
-    <OutputPath>C:\Users\Nicholas\Documents\Visual Studio 2017\Projects\AssimpNet-Next\Docs\</OutputPath>
+    <OutputPath>C:\Users\Nicholas\Documents\Visual Studio 2017\Projects\AssimpNet\Docs\</OutputPath>
     <HtmlHelpName>AssimpNet Documentation %28October 2018%29</HtmlHelpName>
     <Language>en-US</Language>
     <PresentationStyle>VS2013</PresentationStyle>
@@ -25,7 +25,8 @@
     </VendorName>
     <DocumentationSources>
       <DocumentationSource sourceFile="AssimpNet\bin\Release\netstandard1.3\AssimpNet.dll" />
-<DocumentationSource sourceFile="AssimpNet\bin\Release\netstandard1.3\AssimpNet.xml" /></DocumentationSources>
+      <DocumentationSource sourceFile="AssimpNet\bin\Release\netstandard1.3\AssimpNet.xml" />
+    </DocumentationSources>
     <HelpTitle>AssimpNet Documentation %28October 2018%29</HelpTitle>
     <CopyrightText>Copyright &amp;#169%3b 2012-2018 AssimpNet - Nicholas Woodfield. All rights reserved.</CopyrightText>
     <NamespaceSummaries>

AssimpNet/AssimpContext.cs

@@ -179,6 +179,8 @@ public AssimpContext()
         /// <summary>
         /// Imports a model from the stream without running any post-process steps. The importer sets configurations
         /// and loads the model into managed memory, releasing the unmanaged memory used by Assimp. It is up to the caller to dispose of the stream.
+        /// If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ImportFile" family of functions.
         /// </summary>
         /// <param name="stream">Stream to read from</param>
         /// <param name="formatHint">Optional format extension to serve as a hint to Assimp to choose which importer to use. If null or empty, the system will
@@ -192,8 +194,9 @@ public Scene ImportFileFromStream(Stream stream, String formatHint = null)
         }
 
         /// <summary>
-        /// Imports a model from the stream. The importer sets configurations
-        /// and loads the model into managed memory, releasing the unmanaged memory used by Assimp. It is up to the caller to dispose of the stream.
+        /// Imports a model from the stream. The importer sets configurations and loads the model into managed memory, releasing the unmanaged memory 
+        /// used by Assimp. It is up to the caller to dispose of the stream. If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ImportFile" family of functions.
         /// </summary>
         /// <param name="stream">Stream to read from</param>
         /// <param name="postProcessFlags">Post processing flags, if any</param>
@@ -617,7 +620,9 @@ public ExportDataBlob ConvertFromFileToBlob(String inputFilename, PostProcessSte
         #region Stream to File
 
         /// <summary>
-        /// Converts the model contained in the stream to the specified format and save it to a file.
+        /// Converts the model contained in the stream to the specified format and save it to a file. It is up to the caller to dispose of the stream.
+        /// If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ConvertFromFileToFile" family of functions.
         /// </summary>
         /// <param name="inputStream">Stream to read from</param>
         /// <param name="importFormatHint">Optional format extension to serve as a hint to Assimp to choose which importer to use. If null or empty, the system will
@@ -633,7 +638,9 @@ public bool ConvertFromStreamToFile(Stream inputStream, String importFormatHint,
         }
 
         /// <summary>
-        /// Converts the model contained in the stream to the specified format and save it to a file.
+        /// Converts the model contained in the stream to the specified format and save it to a file. It is up to the caller to dispose of the stream.
+        /// If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ConvertFromFileToFile" family of functions.
         /// </summary>
         /// <param name="inputStream">Stream to read from</param>
         /// <param name="importFormatHint">Optional format extension to serve as a hint to Assimp to choose which importer to use. If null or empty, the system will
@@ -650,7 +657,9 @@ public bool ConvertFromStreamToFile(Stream inputStream, String importFormatHint,
         }
 
         /// <summary>
-        /// Converts the model contained in the stream to the specified format and save it to a file.
+        /// Converts the model contained in the stream to the specified format and save it to a file. It is up to the caller to dispose of the stream.
+        /// If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ConvertFromFileToFile" family of functions.
         /// </summary>
         /// <param name="inputStream">Stream to read from</param>
         /// <param name="importFormatHint">Optional format extension to serve as a hint to Assimp to choose which importer to use. If null or empty, the system will
@@ -705,7 +714,9 @@ public bool ConvertFromStreamToFile(Stream inputStream, String importFormatHint,
         #region Stream to Blob
 
         /// <summary>
-        /// Converts the model contained in the stream to the specified format and save it to a data blob.
+        /// Converts the model contained in the stream to the specified format and save it to a data blob. It is up to the caller to dispose of the stream.
+        /// If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ConvertFromFileToBlob" family of functions.
         /// </summary>
         /// <param name="inputStream">Stream to read from</param>
         /// <param name="importFormatHint">Optional format extension to serve as a hint to Assimp to choose which importer to use. If null or empty, the system will
@@ -720,7 +731,9 @@ public ExportDataBlob ConvertFromStreamToBlob(Stream inputStream, String importF
         }
 
         /// <summary>
-        /// Converts the model contained in the stream to the specified format and save it to a data blob.
+        /// Converts the model contained in the stream to the specified format and save it to a data blob. It is up to the caller to dispose of the stream.
+        /// If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ConvertFromFileToBlob" family of functions.
         /// </summary>
         /// <param name="inputStream">Stream to read from</param>
         /// <param name="importFormatHint">Optional format extension to serve as a hint to Assimp to choose which importer to use. If null or empty, the system will
@@ -736,7 +749,9 @@ public ExportDataBlob ConvertFromStreamToBlob(Stream inputStream, String importF
         }
 
         /// <summary>
-        /// Converts the model contained in the stream to the specified format and save it to a data blob.
+        /// Converts the model contained in the stream to the specified format and save it to a data blob. It is up to the caller to dispose of the stream.
+        /// If the format is distributed across multiple files/streams, set a custom <see cref="IOSystem"/>
+        /// and use the "ConvertFromFileToBlob" family of functions.
         /// </summary>
         /// <param name="inputStream">Stream to read from</param>
         /// <param name="importFormatHint">Optional format extension to serve as a hint to Assimp to choose which importer to use. If null or empty, the system will

AssimpNet/FileIOSystem.cs

@@ -171,6 +171,9 @@ public override long Write(byte[] dataToWrite, long count)
             if(m_fileStream == null || !m_fileStream.CanWrite)
                 throw new IOException("Stream is not writable.");
 
+            if(m_fileStream.Position >= m_fileStream.Length)
+                return 0;
+
             m_fileStream.Write(dataToWrite, (int) m_fileStream.Position, (int) count);
 
             return count;
@@ -187,6 +190,9 @@ public override long Read(byte[] dataRead, long count)
             if(m_fileStream == null || !m_fileStream.CanRead)
                 throw new IOException("Stream is not readable.");
 
+            if(m_fileStream.Position >= m_fileStream.Length)
+                return 0;
+
             m_fileStream.Read(dataRead, (int) m_fileStream.Position, (int) count);
 
             return count;

AssimpNet/IOStream.cs

@@ -228,6 +228,9 @@ private UIntPtr OnAiFileWriteProc(IntPtr file, IntPtr dataToWrite, UIntPtr sizeO
             long longNum = (long) numElements.ToUInt64();
             long count = longSize * longNum;
 
+            if(count == 0)
+                return UIntPtr.Zero;
+
             byte[] byteBuffer = GetByteBuffer(longSize, longNum);
             MemoryHelper.Read<byte>(dataToWrite, byteBuffer, 0, (int) count);
 
@@ -258,7 +261,9 @@ private UIntPtr OnAiFileReadProc(IntPtr file, IntPtr dataRead, UIntPtr sizeOfEle
             try
             {
                 actualCount = Read(byteBuffer, count);
-                MemoryHelper.Write<byte>(dataRead, byteBuffer, 0, (int) actualCount);
+
+                if(actualCount > 0)
+                    MemoryHelper.Write<byte>(dataRead, byteBuffer, 0, (int) actualCount);
             }
             catch(Exception) { /*Assimp will report an IO error*/ }