Opengl OpenTK - White screen when drawing depth Buffer

Question

I am currently trying to add shadows with Shadow Mapping to my 3D Engine.

First I render the scene from the light's point of view, and save the depth values in a texture. Then I use the defeault FBO to draw from the texture. Just like in this tutorial. The problem is that my screen stays white, no matter where I move.

GL.GetError() outputs noError and the SSBO's which I use in vertex shader have the right values. GL.CheckFramebufferStatus() returns FramebufferCompleteExt.

This is how I create the FBO for depth values:

_depthMapFBO = GL.GenFramebuffer();
_depthMapFBOColorBuffer = BufferObjects.FBO_TextureAttachment(_depthMapFBO, PixelInternalFormat.DepthComponent, PixelFormat.DepthComponent, FramebufferAttachment.DepthAttachment, 1024, 1024);
GL.BindFramebuffer(FramebufferTarget.Framebuffer, _depthMapFBO);
GL.DrawBuffer(DrawBufferMode.None);
GL.ReadBuffer(ReadBufferMode.None);

====================================

public static int FBO_TextureAttachment(int FrameBuffer, PixelInternalFormat PixelInternalFormat, PixelFormat PixelFormat, FramebufferAttachment FramebufferAttachment, int Width, int Height)
{
    // PixelInternalFormat = DepthComponent && PixelFormat = DepthComponent && FramebufferAttachment = DepthAttachment && Width, Height = 1024, 

    GL.BindFramebuffer(FramebufferTarget.Framebuffer, FrameBuffer);
    int _texture = GL.GenTexture();
            
    GL.BindTexture(TextureTarget.Texture2D, _texture);
    GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat, Width, Height, 0, PixelFormat, PixelType.Float, IntPtr.Zero);

    GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)All.Nearest);
    GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)All.Nearest);
    GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)All.Repeat);
    GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)All.Repeat);

    GL.FramebufferTexture2D(FramebufferTarget.Framebuffer, FramebufferAttachment, TextureTarget.Texture2D, _texture, 0);
    return _texture;
}

In my Render function it looks like this:

GL.BindFramebuffer(FramebufferTarget.Framebuffer, _depthMapFBO);
GL.Clear(ClearBufferMask.DepthBufferBit);

GL.Viewport(0, 0, 1024, 1024);
_simpleDepthProgram.Use();

float _nearPlane = 1.0f, _farPlane = 100f;
_lightProjection = Matrix4.CreateOrthographicOffCenter(-100.0f, 100.0f, -100.0f, 100.0f, _nearPlane, _farPlane);
_ligthView = Matrix4.LookAt(_allLamps[0].Position, new Vector3(0f), new Vector3(0.0f, 1.0f, 0.0f));

_lightSpaceMatrix = _lightProjection * _ligthView;
GL.UniformMatrix4(21, false, ref _lightSpaceMatrix);

// Copy all SSBO's 

GL.ActiveTexture(TextureUnit.Texture2);
GL.BindTexture(TextureTarget.Texture2D, _depthMapFBOColorBuffer);
Scene();

And the shader where I draw the depthMap:

#version 450 core
out vec4 FragColor;

uniform sampler2D scene;
uniform sampler2D bloomed;
uniform sampler2D depthMap;

uniform float zNear;
uniform float zFar;

float LinearizeDepth(float depth)
{
    float z = depth * 2.0 - 1.0; // Back to NDC 
    return (2.0 * zNear * zFar) / (zFar + zNear - z * (zFar - zNear));  
}

in vec2 TexCoord;
void main()
{ 
    float depthValue = texture(depthMap, TexCoord).r;
    //float depth = LinearizeDepth(gl_FragCoord.z) / far; // only for perspective 
    FragColor = vec4(vec3(depthValue), 1.0);
}

Answer 1

The computation of the _lightSpaceMatrix is wrong. The OpenTK matrix multiplication is reversed. See Problem with matrices #687:

Because of how matrices are treated in C# and OpenTK, multiplication order is inverted from what you might expect in C/C++ and GLSL. This is an old artefact in the library, and it's too late to change now, unfortunately.

Swap the _ligthView and _lightProjection when you multiply the matrices:

_lightSpaceMatrix = _lightProjection * _ligthView;

_lightSpaceMatrix = _ligthView * _lightProjection;