Pencil.Gaming

Pencil.Gaming is a gaming library for C#, providing support for OpenGL, GLFW, OpenAL and Lua. It's a stable, cross-platform, open-source (some prefer the term "free") alternative to libraries like XNA, which has pretty much died now, OpenTK, which hasn't been updated for about a year, and SharpDX, which is not cross-platform. A feature that Pencil.Gaming has over most other C# gaming libraries, is that users do not need to install any redistributables besides Mono/.NET!

The OpenGL implementation is based on the OpenTK source code.

Functionality and stability

GLFW2

Platform	OpenGL core	OpenGL extensions	GLFW	OpenAL
Linux 64-bit	Stable	Stable	Stable	Stable
Linux 32-bit	Stable	Stable	Stable	Stable
Windows 64-bit	Stable	Stable	Stable	Stable
Windows 32-bit	Stable	Stable	Stable	Stable
Mac OS X	Stable	Stable	Stable	Stable

GLFW3

Platform	OpenGL core	OpenGL extensions	GLFW	OpenAL
Linux 64-bit	Stable	Stable	Stable	Stable
Linux 32-bit	Stable	Stable	Broken	Stable
Windows 64-bit	Stable	Stable	Stable	Stable
Windows 32-bit	Stable	Stable	Presumed Stable	Stable
Mac OS X	Stable	Stable	Stable*	Stable

*Both 32 and 64-bit versions provided for Mac OS X, but mono is realistically only available for 32-bit, so those are recommended.

Fixing the DllNotFoundException

When running a Pencil.Gaming application, it's unfortunately required that you set your .NET working directory to the directory of the application. Not doing so will result in a DllNotFoundException. This should probably be the first thing in your main function:

 Environment.CurrentDirectory = Path.GetDirectoryName(typeof(Program).Assembly.Location);

When using Mono, it's also quite important that you have the Pencil.Gaming.dll.config file in the same directory as Pencil.Gaming.dll.

Callback Example

For a quick example of the callbacks, such as the input, see: https://gist.github.com/andykorth/b6abf59895c8f6a67964

Image loading utility

int image = GL.Utils.LoadImage("myfile.png"); // Works with multiple file formats
GL.BindTexture(TextureTarget.Texture2D, image);

GL.Begin(BeginMode.TriangleStrip);
  GL.TexCoord2(0f, 1f);
  GL.Vertex2(0.1f, 0.9f);
  GL.TexCoord2(0f, 0f);
  GL.Vertex2(0.1f, 0.1f);
  GL.TexCoord2(1f, 1f);
  GL.Vertex2(0.9f, 0.9f);
  GL.TexCoord2(1f, 0f);
  GL.Vertex2(0.9f, 0.1f);
GL.End();

GL.DeleteTextures(1, ref image);

Model loading utility

Fields

int modelVbo;
int indexVbo;
int numberOfIndices;

During program initialization

GL.Enable(EnapleCap.DepthTest);

Vector4[] vertices;
Vector3[] normals;
Vector2[] texCoords;
int[] indices;
GL.Utils.LoadModel("model.obj", out vertices, out normals, out texCoords, out indices, false);

numberOfIndices = indices.Length;

GL.GenBuffers(1, out modelVbo);
GL.BindBuffer(BufferTarget.ArrayBuffer, modelVbo);
GL.BufferData(BufferTarget.ArrayBuffer, new IntPtr(vertices.Length * 4 * sizeof(float)), vertices, BufferUsageHint.StaticDraw);
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);

GL.GenBuffers(1, out indexVbo);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, indexVbo);
GL.BufferData(BufferTarget.ElementArrayBuffer, new IntPtr(indices.Length * sizeof(int)), indices, BufferUsageHint.StaticDraw);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, 0);

In the draw function

// NOTE: This uses legacy OpenGL, just to fit in the readme...
GL.EnableClientState(ArrayCap.VertexArray);

GL.BindBuffer(BufferTarget.ArrayBuffer, modelVbo);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, indexVbo);

GL.VertexPointer(4, VertexPointerType.Float, 4 * sizeof(float), 0);
GL.DrawElements(BeginMode.Triangles, numberOfIndices, DrawElementsType.UnsignedInt, 0);

GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, 0);

GL.DisableClientState(ArrayCap.VertexArray);

During cleanup

GL.DeleteBuffers(1, ref modelVbo);
GL.DeleteBuffers(1, ref indexVbo);

Sample usage (OpenAL)

Another utility is the AL.Utils.BufferFromWav utility, which is able to load wave files into an OpenAL buffer. Similarly, there's the AL.Utils.BufferFromOgg utility, allowing Ogg/Vorbis file loading.

uint buffer = AL.Utils.BufferFromWav("MyWaveFile.wav");
uint source;
AL.GenSources(1, out source);

AL.Source(source, ALSourcei.Buffer, (int) buffer);
AL.Source(source, ALSourceb.Looping, true);

AL.SourcePlay(source);

// ...
// ...

// When cleaning up:
AL.DeleteSources(1, ref source);
AL.DeleteBuffers(1, ref buffer);

Other Resources

• Collada Importer