/// <summary>
/// Creates a framebuffer object and its associated resources (depth and frame buffers).
/// </summary>
/// <param name="size">Specifies the size (in pixels) of the framebuffer and its associated buffers.</param>
/// <param name="attachments">Specifies the attachments to use for the frame buffer.</param>
/// <param name="format">Specifies the internal pixel format for the frame buffer.</param>
/// <param name="mipmaps">Specifies whether to build mipmaps after the frame buffer is unbound.</param>
/// <param name="filterType">Specifies the type of filtering to apply to the frame buffer when bound as a texture.</param>
/// <param name="pixelType">Specifies the pixel type to use for the underlying format of the frame buffer.</param>
public FBO(Size size, FramebufferAttachment[] attachments, PixelInternalFormat format, bool mipmaps = false, TextureParameter filterType = TextureParameter.Linear, PixelType pixelType = PixelType.UnsignedByte)
{
this.Size = size;
this.Attachments = attachments;
this.Format = format;
this.MipMaps = mipmaps;
// First create the framebuffer
BufferID = Gl.GenFramebuffer();
Gl.BindFramebuffer(FramebufferTarget.Framebuffer, BufferID);
if (Attachments.Length == 1 && Attachments[0] == FramebufferAttachment.DepthAttachment)
{
// if this is a depth attachment only
TextureID = new uint[] { Gl.GenTexture() };
Gl.BindTexture(TextureTarget.Texture2D, TextureID[0]);
Gl.TexImage2D(TextureTarget.Texture2D, 0, Format, Size.Width, Size.Height, 0, PixelFormat.DepthComponent, PixelType.Float, IntPtr.Zero);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, TextureParameter.Nearest);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, TextureParameter.Nearest);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, TextureParameter.ClampToEdge);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, TextureParameter.ClampToEdge);
Gl.FramebufferTexture(FramebufferTarget.Framebuffer, FramebufferAttachment.DepthAttachment, TextureID[0], 0);
Gl.DrawBuffer(DrawBufferMode.None);
Gl.ReadBuffer(ReadBufferMode.None);
}
else
{
// Create n texture buffers (known by the number of attachments)
TextureID = new uint[Attachments.Length];
Gl.GenTextures(Attachments.Length, TextureID);
// Bind the n texture buffers to the framebuffer
for (int i = 0; i < Attachments.Length; i++)
{
Gl.BindTexture(TextureTarget.Texture2D, TextureID[i]);
Gl.TexImage2D(TextureTarget.Texture2D, 0, Format, Size.Width, Size.Height, 0, PixelFormat.Rgba, pixelType, IntPtr.Zero);
if (MipMaps)
{
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, TextureParameter.Linear);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, TextureParameter.LinearMipMapLinear);
Gl.GenerateMipmap(GenerateMipmapTarget.Texture2D);
}
else
{
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, filterType);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, filterType);
}
Gl.FramebufferTexture(FramebufferTarget.Framebuffer, Attachments[i], TextureID[i], 0);
}
// Create and attach a 24-bit depth buffer to the framebuffer
DepthID = Gl.GenTexture();
Gl.BindTexture(TextureTarget.Texture2D, DepthID);
Gl.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Depth24Stencil8, Size.Width, Size.Height, 0, PixelFormat.DepthStencil, PixelType.UnsignedInt248, IntPtr.Zero);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, TextureParameter.Nearest);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, TextureParameter.Nearest);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, TextureParameter.ClampToEdge);
Gl.TexParameteri(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, TextureParameter.ClampToEdge);
Gl.FramebufferTexture(FramebufferTarget.Framebuffer, FramebufferAttachment.DepthAttachment, DepthID, 0);
Gl.FramebufferTexture(FramebufferTarget.Framebuffer, FramebufferAttachment.StencilAttachment, DepthID, 0);
}
// Build the framebuffer and check for errors
FramebufferErrorCode status = Gl.CheckFramebufferStatus(FramebufferTarget.Framebuffer);
if (status != FramebufferErrorCode.FramebufferComplete)
{
Console.WriteLine("Frame buffer did not compile correctly. Returned {0}, glError: {1}", status.ToString(), Gl.GetError().ToString());
}
Gl.BindFramebuffer(FramebufferTarget.Framebuffer, 0);
}