MoonWorks/src/Game.cs

using System;
using SDL2;
using Campari;
using System.Collections.Generic;

namespace MoonWorks
{
    public abstract class Game
    {
        private bool quit = false;
        private double timestep;
        ulong currentTime = SDL.SDL_GetPerformanceCounter();
        double accumulator = 0;

        public IntPtr WindowHandle { get; }
        public GraphicsDevice GraphicsDevice { get; }

        public Input Input { get; }

        private Dictionary<PresentMode, RefreshCS.Refresh.PresentMode> moonWorksToRefreshPresentMode = new Dictionary<PresentMode, RefreshCS.Refresh.PresentMode>
        {
            { PresentMode.Immediate, RefreshCS.Refresh.PresentMode.Immediate },
            { PresentMode.Mailbox, RefreshCS.Refresh.PresentMode.Mailbox },
            { PresentMode.FIFO, RefreshCS.Refresh.PresentMode.FIFO },
            { PresentMode.FIFORelaxed, RefreshCS.Refresh.PresentMode.FIFORelaxed }
        };

        public Game(uint windowWidth, uint windowHeight, PresentMode presentMode, int targetTimestep = 60, bool debugMode = false)
        {
            timestep = 1.0 / targetTimestep;

            if (SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_TIMER | SDL.SDL_INIT_GAMECONTROLLER) < 0)
            {
                System.Console.WriteLine("Failed to initialize SDL!");
                return;
            }

            WindowHandle = SDL.SDL_CreateWindow(
                "CampariTest",
                SDL.SDL_WINDOWPOS_UNDEFINED,
                SDL.SDL_WINDOWPOS_UNDEFINED,
                (int)windowWidth,
                (int)windowHeight,
                SDL.SDL_WindowFlags.SDL_WINDOW_VULKAN
            );

            GraphicsDevice = new GraphicsDevice(WindowHandle, moonWorksToRefreshPresentMode[presentMode], debugMode);

            Input = new Input();
        }

        public void Run()
        {
            while (!quit)
            {
                var newTime = SDL.SDL_GetPerformanceCounter();
                double frameTime = (newTime - currentTime) / (double)SDL.SDL_GetPerformanceFrequency();

                if (frameTime > 0.25)
                {
                    frameTime = 0.25;
                }

                currentTime = newTime;

                accumulator += frameTime;

                bool updateThisLoop = (accumulator >= timestep);

                if (!quit)
                {
                    while (accumulator >= timestep)
                    {
                        SDL.SDL_PumpEvents();
                        Input.Update();

                        Update(timestep);

                        accumulator -= timestep;
                    }

                    if (updateThisLoop)
                    {
                        Draw();
                    }
                }
            }
        }

        protected abstract void Update(double dt);

        protected abstract void Draw();
    }
}