feat: backporting existing raylib-cs examples and new official raylib examples to WASM, adopting raylib's original code style

Examples/Textures/MagnifyingGlass.cs

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+/*******************************************************************************************
+*
+*   raylib textures example - magnifying glass
+*
+*   Example complexity rating: [★★★☆] 3/4
+*
+*   Example originally created with raylib 5.6, last time updated with raylib 5.6
+*
+*   Example contributed by Luke Vaughan (@badram) and reviewed by Ramon Santamaria (@raysan5)
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2026 Luke Vaughan (@badram)
+*
+********************************************************************************************/
+
+using System.Numerics;
+using static Raylib_cs.Raylib;
+
+namespace Examples.Textures;
+
+public partial class MagnifyingGlass : IExample
+{
+    private const int screenWidth = 800;
+    private const int screenHeight = 450;
+
+    public string Name => "Textures / Magnifying Glass";
+
+    public string Title => "raylib [textures] example - magnifying glass";
+
+    private Texture2D bunny;
+    private Texture2D parrots;
+    private Texture2D mask;
+    private RenderTexture2D magnifiedWorld;
+    private Camera2D camera;
+
+    public void Init()
+    {
+        bunny = LoadTexture("resources/raybunny.png");
+        parrots = LoadTexture("resources/parrots.png");
+
+        // Use image draw to generate a mask texture instead of loading it from a file.
+        var circle = GenImageColor(256, 256, Color.Blank);
+        ImageDrawCircle(ref circle, 128, 128, 128, Color.White);
+        mask = LoadTextureFromImage(circle); // Copy the mask image from RAM to VRAM
+        UnloadImage(circle); // Unload the image from RAM
+
+        magnifiedWorld = LoadRenderTexture(256, 256);
+
+        camera = new Camera2D();
+        // Set magnifying glass zoom
+        camera.Zoom = 2;
+        // Offset by half the size of the magnifying glass to counteract drawing the texture centered on the mouse position
+        camera.Offset = new Vector2(128, 128);
+    }
+
+    public void Update()
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        var mPos = GetMousePosition();
+        camera.Target = mPos;
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+        ClearBackground(Color.RayWhite);
+
+        // Draw the normal version of the world
+        DrawTexture(parrots, 144, 33, Color.White);
+        DrawText("Use the magnifying glass to find hidden bunnies!", 154, 6, 20, Color.Black);
+
+        // Render to a the magnifying glass
+        BeginTextureMode(magnifiedWorld);
+        ClearBackground(Color.RayWhite);
+
+        BeginMode2D(camera);
+        // Draw the same things in the magnified world as were in the normal version
+        DrawTexture(parrots, 144, 33, Color.White);
+        DrawText("Use the magnifying glass to find hidden bunnies!", 154, 6, 20, Color.Black);
+
+        // Draw bunnies only in the magnified world.
+        // BLEND_MULTIPLIED lets them take on the color of the image below them.
+        BeginBlendMode(BlendMode.Multiplied);
+        DrawTexture(bunny, 250, 350, Color.White);
+        DrawTexture(bunny, 500, 100, Color.White);
+        DrawTexture(bunny, 420, 300, Color.White);
+        DrawTexture(bunny, 650, 10, Color.White);
+        EndBlendMode();
+        EndMode2D();
+
+        // Mask the magnifying glass view texture to a circle
+        // To make the mask affect only alpha, a CUSTOM blend mode is used with SEPARATE color/alpha functions
+        BeginBlendMode(BlendMode.CustomSeparate);
+        // C: Color, A: Alpha, s: source (texture to draw), d: destination (texture drawn to)
+        //   glSrcRGB: RL_ZERO      - Cs * 0 = 0  - discard source rgb because we don't want to draw our texture's colors at all
+        //   glDstRGB: RL_ONE       - Cd * 1 = Cd - use destination colors unmodified
+        //   glSrcAlpha: RL_ONE     - As * 1 = As - use source alpha unmodified
+        //   glDstAlpha: RL_ZERO    - Ad * 0 = 0  - discard destination alpha
+        //   glEqRGB: RL_FUNC_ADD   - Cs(0) + Cd = Cd - destination color is unmodified
+        //   glEqAlpha: RL_FUNC_ADD - As + Ad(0) = As - destination alpha is set to source alpha
+        Rlgl.SetBlendFactorsSeparate(Rlgl.ZERO, Rlgl.ONE, Rlgl.ONE, Rlgl.ZERO, Rlgl.FUNC_ADD, Rlgl.FUNC_ADD);
+        DrawTexture(mask, 0, 0, Color.White);
+        EndBlendMode();
+        EndTextureMode();
+
+        // Draw magnifiedWorld to screen, centered on cursor
+        DrawTextureRec(magnifiedWorld.Texture, new Rectangle(0, 0, 256, -256), new Vector2(mPos.X - 128, mPos.Y - 128), Color.White);
+
+        // Draw the outer ring of the magnifying glass
+        DrawRing(mPos, 126, 130, 0, 360, 64, Color.Black);
+
+        // Draw floating specular highlight on the glass
+        var rx = mPos.X / 800;
+        var ry = mPos.Y / 800;
+        DrawCircle((int)(mPos.X - 64 * rx) - 32, (int)(mPos.Y - 64 * ry) - 32, 4, ColorAlpha(Color.White, 0.5f));
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    public void Unload()
+    {
+        UnloadTexture(parrots);
+        UnloadTexture(bunny);
+        UnloadTexture(mask);
+        UnloadRenderTexture(magnifiedWorld);
+    }
+
+    public static int Main()
+    {
+        // Initialization
+        //--------------------------------------------------------------------------------------
+        InitWindow(screenWidth, screenHeight, "raylib [textures] example - magnifying glass");
+
+        SetTargetFPS(60);
+        //--------------------------------------------------------------------------------------
+
+        var game = new MagnifyingGlass();
+        game.Init();
+
+        // Main game loop
+        while (!WindowShouldClose())    // Detect window close button or ESC key
+        {
+            game.Update();
+        }
+
+        game.Unload();
+
+        // De-Initialization
+        //--------------------------------------------------------------------------------------
+        CloseWindow();                // Close window and OpenGL context
+        //--------------------------------------------------------------------------------------
+
+        return 0;
+    }
+}