C#游戏开发中精确的时间调配

方法一：参考《精通C#游戏编程》一书。根据学习WorldWind源码可知，WorldWind中采用的方法与该方法基本一致。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace GameLoop//根据需要修改名称空间
{
    public class PreciseTimer
    {
        [System.Security.SuppressUnmanagedCodeSecurity]
        [DllImport("kernel32")]
        private static extern bool QueryPerformanceFrequency(ref long PerformanceFrequency);

        [System.Security.SuppressUnmanagedCodeSecurity]
        [DllImport("kernel32")]
        private static extern bool QueryPerformanceCounter(ref long PerformanceCount);

        long _ticksPerSecond = 0;
        long _previousElapsedTime = 0;

        public PreciseTimer()
        {
            QueryPerformanceFrequency(ref _ticksPerSecond);
            GetElapsedTime(); // Get rid of first rubbish result
        }

        public double GetElapsedTime()
        {
            long time = 0;
            QueryPerformanceCounter(ref time);

            double elapsedTime = (double)(time - _previousElapsedTime) / (double)_ticksPerSecond;
            _previousElapsedTime = time;

            return elapsedTime;
        }
    }
}