feat(csharp): implement

csharp/Makefile

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+raylib_csharp: main.cs
+	mcs main.cs -out:raylib_csharp.exe

csharp/README.md

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+# Raylib in C#
+
+I'm using Mono because i don't like Microsoft.  
+
+## Quick start
+
+```shell
+$ make
+$ mono raylib_csharp.exe
+```
+
+## Credits
+
+- Logo: [Wikipedia](https://wikipedia.org/wiki/File:Logo_C_sharp.svg)

csharp/main.cs

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+using System.Runtime.InteropServices;
+
+static class Program
+{
+    [StructLayout(LayoutKind.Sequential)]
+    struct Texture2D
+    {
+        public uint id;
+        public int width;
+        public int height;
+        public int mipmaps;
+        public int format;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    struct Vector2
+    {
+        public float x;
+        public float y;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    struct Color
+    {
+        public byte r;
+        public byte g;
+        public byte b;
+        public byte a;
+    }
+
+    private const string RAYLIB = "../_raylib-5.5_linux_amd64/lib/libraylib.so";
+
+    [DllImport(RAYLIB)] private static extern void InitWindow(int width, int height, string title);
+
+    [DllImport(RAYLIB)] private static extern void CloseWindow();
+
+    [DllImport(RAYLIB)] private static extern void SetTargetFPS(int fps);
+    [DllImport(RAYLIB)] private static extern void SetRandomSeed(uint seed);
+    [DllImport(RAYLIB)] private static extern int GetRandomValue(int min, int max);
+
+    [DllImport(RAYLIB)] private static extern Texture2D LoadTexture(string file_name);
+    [DllImport(RAYLIB)] private static extern void UnloadTexture(Texture2D texture);
+
+    [DllImport(RAYLIB)] private static extern bool WindowShouldClose();
+    [DllImport(RAYLIB)] private static extern float GetFrameTime();
+
+    [DllImport(RAYLIB)] private static extern void BeginDrawing();
+    [DllImport(RAYLIB)] private static extern void ClearBackground(Color color);
+    [DllImport(RAYLIB)] private static extern void DrawTextureEx(Texture2D texture, Vector2 position, float rotation, float scale, Color tint);
+    [DllImport(RAYLIB)] private static extern void EndDrawing();
+
+    private const int WINDOW_WIDTH = 800;
+    private const int WINDOW_HEIGHT = 600;
+    private const float LOGO_SCALE = 0.05f;
+    private const float LOGO_SPEED = 300;
+
+    private static Color BLACK = new Color() { r = 0, g = 0, b = 0, a = 255 };
+    private static Color WHITE = new Color() { r = 255, g = 255, b = 255, a = 255 };
+
+    public static void Main()
+    {
+        InitWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "Raylib in C#");
+        SetTargetFPS(60);
+
+        Texture2D logo_texture = LoadTexture("./csharp_logo.png");
+
+        int logo_width = (int)(logo_texture.width * LOGO_SCALE);
+        int logo_height = (int)(logo_texture.height * LOGO_SCALE);
+
+        float x = GetRandomValue(0, WINDOW_WIDTH - logo_width);
+        float y = GetRandomValue(0, WINDOW_HEIGHT - logo_height);
+
+        float dx = LOGO_SPEED * (GetRandomValue(0, 1) == 1 ? -1 : 1);
+        float dy = LOGO_SPEED * (GetRandomValue(0, 1) == 1 ? -1 : 1);
+
+        while (!WindowShouldClose())
+        {
+            float delta_time = GetFrameTime();
+
+            x += dx * delta_time;
+            y += dy * delta_time;
+
+            if (x < 0 || (x + logo_width) >= WINDOW_WIDTH - 1)
+            {
+                dx *= -1;
+                x += dx * delta_time;
+            }
+            if (y < 0 || (y + logo_height) >= WINDOW_HEIGHT - 1)
+            {
+                dy *= -1;
+                y += dy * delta_time;
+            }
+
+            BeginDrawing();
+
+            ClearBackground(BLACK);
+            DrawTextureEx(logo_texture, new Vector2() { x = x, y = y }, 0, LOGO_SCALE, WHITE);
+
+            EndDrawing();
+        }
+
+        UnloadTexture(logo_texture);
+        CloseWindow();
+    }
+}