using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using OpenTK.Graphics.OpenGL;

namespace GLFrameworkEngine

{

public partial class Framebuffer : GLObject

{

public FramebufferTarget Target { get; }

public PixelInternalFormat PixelInternalFormat { get; internal set; }

public int Width { get; internal set; }

public int Height { get; internal set; }

public List<IFramebufferAttachment> Attachments { get; }

public Framebuffer(FramebufferTarget framebufferTarget) : base(GL.GenFramebuffer()) {

Target = framebufferTarget;

Attachments = new List<IFramebufferAttachment>();

}

public Framebuffer(FramebufferTarget target, int width, int height,

PixelInternalFormat pixelInternalFormat = PixelInternalFormat.Rgba, int colorAttachmentsCount = 1, bool useDepth = true)

: this(target)

{

if (colorAttachmentsCount < 0)

throw new ArgumentOutOfRangeException(nameof(colorAttachmentsCount), "Color attachment count must be non negative.");

Bind();

PixelInternalFormat = pixelInternalFormat;

Width = width;

Height = height;

if (colorAttachmentsCount > 0)

Attachments = CreateColorAttachments(width, height, colorAttachmentsCount);

if (useDepth)

SetUpRboDepth(width, height);

}

public Framebuffer(FramebufferTarget target, int width, int height, int numSamples,

PixelInternalFormat pixelInternalFormat = PixelInternalFormat.Rgba, int colorAttachmentsCount = 1)

: this(target)

{

if (colorAttachmentsCount < 0)

throw new ArgumentOutOfRangeException(nameof(colorAttachmentsCount), "Color attachment count must be non negative.");

Bind();

PixelInternalFormat = pixelInternalFormat;

Width = width;

Height = height;

Attachments = CreateColorAttachments(width, height, colorAttachmentsCount, numSamples);

SetUpRboDepth(width, height, numSamples);

}

public void Bind() {

GL.BindFramebuffer(Target, ID);

}

public void Unbind() {

GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0);

}

public void Dispose() {

GL.DeleteFramebuffer(ID);

}

public void Resize(int width, int height)

{

Width = width;

Height = height;

foreach (var attatchment in Attachments)

{

if (attatchment is GLTexture2D)

{

var tex = (GLTexture2D)attatchment;

tex.Resize(Width, height);

}

else if (attatchment is DepthTexture)

{

var tex = (DepthTexture)attatchment;

tex.Bind();

GL.TexImage2D(tex.Target, 0, tex.PixelInternalFormat,

Width, Height, 0, tex.PixelFormat, tex.PixelType, IntPtr.Zero);

tex.Unbind();

}

else if(attatchment is Renderbuffer)

{

var buffer = (Renderbuffer)attatchment;

buffer.Bind();

GL.RenderbufferStorage(RenderbufferTarget.Renderbuffer, buffer.InternalFormat, Width, Height);

buffer.Unbind();

}

}

}

public void DisposeRenderBuffer()

{

foreach (var attatchment in Attachments)

if (attatchment is Renderbuffer)

attatchment.Dispose();

}

public void SetDrawBuffers(params DrawBuffersEnum[] drawBuffers)

{

Bind();

GL.DrawBuffers(drawBuffers.Length, drawBuffers);

}

public void SetReadBuffer(ReadBufferMode readBufferMode)

{

Bind();

GL.ReadBuffer(readBufferMode);

}

public FramebufferErrorCode GetStatus()

{

Bind();

return GL.CheckFramebufferStatus(Target);

}

public void AddAttachment(FramebufferAttachment attachmentPoint, IFramebufferAttachment attachment)

{

// Check if the dimensions are uninitialized.

if (Attachments.Count == 0 && Width == 0 && Height == 0)

{

Width = attachment.Width;

Height = attachment.Height;

}

if (attachment.Width != Width || attachment.Height != Height)

throw new ArgumentOutOfRangeException(nameof(attachment), "The attachment dimensions do not match the framebuffer's dimensions.");

attachment.Attach(attachmentPoint, this);

Attachments.Add(attachment);

}

private GLTexture2D CreateColorAttachment(int width, int height)

{

GLTexture2D texture = GLTexture2D.CreateUncompressedTexture(width, height,

PixelInternalFormat, PixelFormat.Rgba, PixelType.Float);

// Don't use mipmaps for color attachments.

texture.MinFilter = TextureMinFilter.Linear;

texture.MagFilter = TextureMagFilter.Linear;

texture.UpdateParameters();

return texture;

}

private GLTexture2D CreateColorAttachment(int width, int height, int numSamples)

{

GLTexture2D texture = GLTexture2DMultiSampled.CreateUncompressedTexture(width, height,

PixelInternalFormat, PixelFormat.Rgba, PixelType.Float);

// Don't use mipmaps for color attachments.

texture.MinFilter = TextureMinFilter.Linear;

texture.MagFilter = TextureMagFilter.Linear;

texture.UpdateParameters();

return texture;

}

private void SetUpRboDepth(int width, int height)

{

// Render buffer for the depth attachment, which is necessary for depth testing.

Renderbuffer rboDepth = new Renderbuffer(width, height, RenderbufferStorage.Depth24Stencil8);

AddAttachment(FramebufferAttachment.DepthStencilAttachment, rboDepth);

}

private void SetUpRboDepth(int width, int height, int numSamples)

{

// Render buffer for the depth attachment, which is necessary for depth testing.

Renderbuffer rboDepth = new Renderbuffer(width, height, numSamples, RenderbufferStorage.Depth24Stencil8);

AddAttachment(FramebufferAttachment.DepthStencilAttachment, rboDepth);

}

private List<IFramebufferAttachment> CreateColorAttachments(int width, int height, int colorAttachmentsCount)

{

var colorAttachments = new List<IFramebufferAttachment>();

List<DrawBuffersEnum> attachmentEnums = new List<DrawBuffersEnum>();

for (int i = 0; i < colorAttachmentsCount; i++)

{

DrawBuffersEnum attachmentPoint = DrawBuffersEnum.ColorAttachment0 + i;

attachmentEnums.Add(attachmentPoint);

GLTexture2D texture = CreateColorAttachment(width, height);

colorAttachments.Add(texture);

AddAttachment((FramebufferAttachment)attachmentPoint, texture);

}

SetDrawBuffers(attachmentEnums.ToArray());

return colorAttachments;

}

private List<IFramebufferAttachment> CreateColorAttachments(int width, int height, int colorAttachmentsCount, int numSamples)

{

var colorAttachments = new List<IFramebufferAttachment>();

List<DrawBuffersEnum> attachmentEnums = new List<DrawBuffersEnum>();

for (int i = 0; i < colorAttachmentsCount; i++)

{

DrawBuffersEnum attachmentPoint = DrawBuffersEnum.ColorAttachment0 + i;

attachmentEnums.Add(attachmentPoint);

GLTexture2D texture = CreateColorAttachment(width, height, numSamples);

colorAttachments.Add(texture);

AddAttachment((FramebufferAttachment)attachmentPoint, texture);

}

SetDrawBuffers(attachmentEnums.ToArray());

return colorAttachments;

}

}

}