raylib-cs/Examples/Textures/Bunnymark.cs

/*******************************************************************************************
*
*   raylib [textures] example - bunnymark
*
*   Example complexity rating: [★★★☆] 3/4
*
*   Example originally created with raylib 1.6, last time updated with raylib 2.5
*
*   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) 2014-2025 Ramon Santamaria (@raysan5), 2024 Moritz Voss (@thygrrr)
*
********************************************************************************************/

using System.Diagnostics;
using System.Numerics;
using static Raylib_cs.Raylib;

namespace Examples.Textures;

public partial class Bunnymark : IExample
{
    private const int screenWidth = 800;
    private const int screenHeight = 450;

    // limits
    private const int MaxBunnies = 500_000;
    private const int BunnyIncrement = 500;
    private const int BunnyDecrement = 2_500;

    private const int TARGET_FPS = 60;

    // This is the maximum amount of elements (quads) per batch
    private const int MAX_BATCH_ELEMENTS = Rlgl.DEFAULT_BATCH_BUFFER_ELEMENTS;

    public string Name => "Textures / Bunnymark";

    public string Title => "raylib [textures] example - bunnymark";

    private record struct Bunny()
    {
        public Vector2 Position { get; set; } = GetMousePosition();
        public Vector2 Speed
        {
            get; set;
        } = new(
            GetRandomValue(-250, 250) / (float)TARGET_FPS,
            GetRandomValue(-250, 250) / (float)TARGET_FPS);
        public Color Color
        {
            get;
        } = new(
            GetRandomValue(50, 240),
            GetRandomValue(80, 240),
            GetRandomValue(100, 240), 255);
    }

    private Texture2D texBunny;
    private Vector2 halfSize;
    private Bunny[] bunnies;
    private int bunniesCount;

    public void Init()
    {
        // Load bunny texture
        texBunny = LoadTexture("resources/wabbit_alpha.png");
        halfSize = new Vector2(texBunny.Width, texBunny.Height) / 2;

        // Initialize bunnies storage
        bunnies = new Bunny[MaxBunnies];
        bunniesCount = 0;
    }

    public void Update()
    {
        // Update
        //----------------------------------------------------------------------------------
        Span<Bunny> bunnies = this.bunnies;

        if (IsMouseButtonDown(MouseButton.Left) && bunniesCount < MaxBunnies)
        {
            // Add a range of new bunnies
            foreach (ref var bunny in bunnies[bunniesCount..(bunniesCount + BunnyIncrement)])
            {
                bunny = new();
            }
            bunniesCount += BunnyIncrement;
        }
        else if (IsMouseButtonDown(MouseButton.Right))
        {
            // Remove the oldest bunnies, shifting them back in the span
            if (bunniesCount > BunnyDecrement)
            {
                bunnies[BunnyDecrement..bunniesCount].CopyTo(bunnies);
            }
            bunniesCount = Math.Max(0, bunniesCount - BunnyDecrement);
        }

        // Update bunnies
        foreach (ref var bunny in bunnies[..bunniesCount])
        {
            // Integrate position
            bunny.Position += bunny.Speed;

            // Bounce bunnies off the screen borders
            bunny.Speed *= (bunny.Position + halfSize) switch
            {
                { X: < 0 or > screenWidth, Y: < 40 or > screenHeight } => new(-1, -1),
                { X: < 0 or > screenWidth } => new(-1, 1),
                { Y: < 40 or > screenHeight } => new(1, -1),
                _ => Vector2.One,
            };
        }
        //----------------------------------------------------------------------------------

        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();
        ClearBackground(Color.RayWhite);

        foreach (var bunny in bunnies[..bunniesCount])
        {
            // NOTE: When internal batch buffer limit is reached (MAX_BATCH_ELEMENTS),
            // a draw call is launched and buffer starts being filled again;
            // before issuing a draw call, updated vertex data from internal CPU buffer is send to GPU...
            // Process of sending data is costly and it could happen that GPU data has not been completely
            // processed for drawing while new data is tried to be sent (updating current in-use buffers)
            // it could generates a stall and consequently a frame drop, limiting the number of drawn bunnies
            DrawTexture(texBunny, (int)bunny.Position.X, (int)bunny.Position.Y, bunny.Color);
        }

        DrawRectangle(0, 0, screenWidth, 40, Color.Black);
        DrawText($"bunnies: {bunniesCount}", 120, 10, 20, Color.Green);
        DrawText($"batched draw calls: {1 + bunniesCount / MAX_BATCH_ELEMENTS}", 320, 10, 20, Color.Maroon);
        DrawText("Left Mouse: Add Bunnies!!! :D", 10, 400, 20, Color.LightGray);
        DrawText("Right Mouse: Remove Bunnies", 10, 420, 20, Color.LightGray);

        DrawFPS(10, 10);

        EndDrawing();
        //----------------------------------------------------------------------------------
    }

    public void Unload()
    {
        UnloadTexture(texBunny);
#if BROWSER
        bunnies = null;
        bunniesCount = 0;
#endif
    }

    public static int Main()
    {
        // Initialization
        //--------------------------------------------------------------------------------------
        InitWindow(screenWidth, screenHeight, "raylib [textures] example - bunnymark");

        SetTargetFPS(TARGET_FPS);
        //--------------------------------------------------------------------------------------

        var game = new Bunnymark();
        game.Init();

        // Main game loop
        while (!WindowShouldClose())
        {
            game.Update();
        }

        game.Unload();

        // De-Initialization
        //--------------------------------------------------------------------------------------
        CloseWindow();
        //--------------------------------------------------------------------------------------

        return 0;
    }

    static Bunnymark()
    {
        Debug.Assert(MaxBunnies % BunnyIncrement == 0 && MaxBunnies % BunnyDecrement == 0,
            "MaxBunnies must be a common multiple of BunnyIncrement and BunnyDecrement.");
    }
}