OpenGL issue: Shader always uses texture from slot 0

[jjb-pro]

Hello,
first, thank you so much for such a great project!

I'm encountering an issue while working with Silk.NET and C# for rendering. I'm developing an application that involves loading models, which is why I have various classes calling rendering methods. The problem I'm facing is related to shader usage, as it seems the shader is always utilizing the texture from the texture slot 0. Let me provide you with the relevant code sections to illustrate the issue:

Mesh class

[NotThreadSafe]
public unsafe void Render()
{
    // Bind the geometry and shader.
    Engine.Instance.GL.BindVertexArray(vertexArray);

    // Bind the material
    material.Render();

    // Draw the geometry.
    Engine.Instance.GL.DrawElements(PrimitiveType.Triangles, (uint)indices.Length, DrawElementsType.UnsignedInt, null);
}

Material Class:

[NotThreadSafe]
public void Render()
{
    // Use the shader program
    Shader.Render();

    // Set the view and projection uniform
    var view = Matrix4x4.CreateLookAt(Camera.ActiveCamera.Transform.Position, Camera.ActiveCamera.Transform.Position + Camera.ActiveCamera.Front, Camera.ActiveCamera.Up);
    var projection = Matrix4x4.CreatePerspectiveFieldOfView(Helpers.Math.DegreesToRadians(Camera.ActiveCamera.Zoom), 800 / 600, 0.1f, 100.0f);

    Shader.SetUniform("uView", view);
    Shader.SetUniform("uProjection", projection);

    int i = 0;
    foreach (var keyValue in _textures)
    {
        Console.WriteLine($"Setting {i}: {keyValue.Key} - {keyValue.Value.combinedFilePath}.");

       keyValue.Value.Render(Silk.NET.OpenGL.TextureUnit.Texture0.Next(i));
       Shader.SetUniform(keyValue.Key, i);

       i++;
    }

    // Set the transform view matrix of the owner
    Shader.SetUniform("uModel", Owner.Transform.ViewMatrix);
}

(Next(int offset) is a custom extension method that allows me to increment the enumeration by the specified value – even if I simply use TextureUnit.Texture1, the shader still only uses texture slot 0.)

Shader class

[NotThreadSafe]
public void SetUniform(string name, float value)
{
    int location = Engine.Instance.GL.GetUniformLocation(shaderLocation, name);
    if (location == -1)
    {
        Logger.Log($"{name} uniform not found on shader {this.name}.", Logger.LogType.error);
        return;
    }

    Console.WriteLine($"Setting {name} to {value}.");
    Engine.Instance.GL.Uniform1(location, value);
}

Texture class

[NotThreadSafe]
public void Render(TextureUnit textureSlot = TextureUnit.Texture0)
{
    Engine.Instance.GL.ActiveTexture(textureSlot);
    Engine.Instance.GL.BindTexture(TextureTarget.Texture2D, _handle);
}

Shader

The shader has a simple structure. It uses various Sampler2D variables, then performs some calculations and displays the texture on the mesh. I have checked the shader in another project – it works.

I have already spent over four hours debugging the code and unfortunately found no error. Furthermore, I would guess it's the order, but even after a few attempted changes it didn't fix anything.

Even though I attempt to set the texture unit to i in the Material class, the shader continues to use the texture from slot 0. I'm unsure what could be causing this behavior. Any insights or suggestions would be greatly appreciated.

[qian-o]

Please overload a method with an int type parameter.

[jjb-pro]

It works now perfectly! And I was already beginning to lose hope. It's the details that matter …
Thank you very, very much!