feat: add shader pipeline and chunk GLSL shaders

Assets/shaders/chunk.frag

@@ -0,0 +1,13 @@
+#version 330 core
+in vec2 vUv;
+in float vShade;
+
+out vec4 FragColor;
+
+uniform sampler2D atlas;
+
+void main()
+{
+    vec4 texel = texture(atlas, vUv);
+    FragColor = vec4(texel.rgb * vShade, 1.0);
+}

Assets/shaders/chunk.vert

@@ -0,0 +1,19 @@
+#version 330 core
+layout(location = 0) in vec3 aPos;
+layout(location = 1) in vec2 aUv;
+layout(location = 2) in float aShade;
+
+out vec2 vUv;
+out float vShade;
+
+uniform mat4 model;
+uniform mat4 view;
+uniform mat4 projection;
+
+void main()
+{
+    vUv = aUv;
+    vShade = aShade;
+    // Vector-on-left convention; matrices are uploaded with transpose=true.
+    gl_Position = vec4(aPos, 1.0) * model * view * projection;
+}

Rendering/Shader.cs

@@ -0,0 +1,64 @@
+using OpenTK.Graphics.OpenGL4;
+using OpenTK.Mathematics;
+
+namespace VoxelEngine.Rendering;
+
+public sealed class Shader : IDisposable
+{
+    private readonly int _handle;
+    private readonly Dictionary<string, int> _uniforms = new();
+
+    public Shader(string vertexPath, string fragmentPath)
+    {
+        int vertex = CompileFromFile(ShaderType.VertexShader, vertexPath);
+        int fragment = CompileFromFile(ShaderType.FragmentShader, fragmentPath);
+
+        _handle = GL.CreateProgram();
+        GL.AttachShader(_handle, vertex);
+        GL.AttachShader(_handle, fragment);
+        GL.LinkProgram(_handle);
+
+        GL.GetProgram(_handle, GetProgramParameterName.LinkStatus, out int linked);
+        if (linked == 0)
+            throw new InvalidOperationException($"Program link failed: {GL.GetProgramInfoLog(_handle)}");
+
+        GL.DetachShader(_handle, vertex);
+        GL.DetachShader(_handle, fragment);
+        GL.DeleteShader(vertex);
+        GL.DeleteShader(fragment);
+    }
+
+    public void Use() => GL.UseProgram(_handle);
+
+    public void SetMatrix4(string name, Matrix4 value) =>
+        GL.UniformMatrix4(Location(name), true, ref value);
+
+    public void SetInt(string name, int value) =>
+        GL.Uniform1(Location(name), value);
+
+    private int Location(string name)
+    {
+        if (!_uniforms.TryGetValue(name, out int location))
+        {
+            location = GL.GetUniformLocation(_handle, name);
+            _uniforms[name] = location;
+        }
+        return location;
+    }
+
+    private static int CompileFromFile(ShaderType type, string path)
+    {
+        string source = File.ReadAllText(path);
+        int shader = GL.CreateShader(type);
+        GL.ShaderSource(shader, source);
+        GL.CompileShader(shader);
+
+        GL.GetShader(shader, ShaderParameter.CompileStatus, out int compiled);
+        if (compiled == 0)
+            throw new InvalidOperationException($"{type} compile failed ({path}): {GL.GetShaderInfoLog(shader)}");
+
+        return shader;
+    }
+
+    public void Dispose() => GL.DeleteProgram(_handle);
+}