用时间和金钱的百分比计算浮动

Question

我想在我的游戏中制作结构的构建过程。仅当时间百分比 (timer/neededTime*100) 小于金钱百分比 (player.money/neededMoney*100) 时，该过程才会继续。每一帧，具体金额，应该从player.money减少，这样整个过程的结束money.player = money.player - neededMoney。我不知道如何计算每帧从钱中减少的浮动。

Answer 1

您需要在每个neededTime 单元中减去neededMoney 的一部分？

每neededTime单位，我假设它是一个非负非零整数值，你需要减去neededMoney/neededTime。

每帧，代码看起来像这样。假设framesPerSecond 是一个常数，neededTime 是秒。

var secondsPerFrame = 1/(float)framesPerSecond;
var moneyPerSecond = neededMoney/(float)neededTime;
var moneyPerFrame = moneyPerSecond * secondsPerFrame;
//The above can be rewritten as:
//var moneyPerFrame = neededMoney/(float)neededTime/(float)framesPerSecond);

if (player.money >= moneyPerFrame)
{
    player.money -= moneyPerFrame;
}

更新以支持更改帧速率

我编写了一个类，它应该能够处理不断变化的帧速率和可用资金不足的问题。在每一帧（或在适当的时候），调用GetValueToSubtract() 方法。

public class BuildingExpenseCalculator
{
    private readonly IAccount _account;
    private readonly float _moneyNeeded;
    private readonly float _spendingRate;

    private float _moneyNeededRemaining;
    private DateTime _lastSubtract;

    public BuildingExpenseCalculator(IAccount account, float moneyNeeded, TimeSpan timeNeeded)
    {
        _account = account;
        _moneyNeeded = moneyNeeded;

        _spendingRate = moneyNeeded/(float) timeNeeded.TotalSeconds;
    }

    public void StartCalculation()
    {
        _lastSubtract = DateTime.Now;
        _moneyNeededRemaining = _moneyNeeded;
    }

    public float GetValueToSubtract()
    {
        var now = DateTime.Now;
        var timePassedSinceLastSubtract = now - _lastSubtract;
        var moneyToSubtractSinceLast = (float)(_spendingRate*timePassedSinceLastSubtract.TotalSeconds);

        // Ensure we do not exceed the remaining money that is needed.
        moneyToSubtractSinceLast = Math.Min(moneyToSubtractSinceLast, _moneyNeededRemaining);

        // Ensure we do not spent more money than is available in the account.
        moneyToSubtractSinceLast = Math.Min(moneyToSubtractSinceLast, _account.AvailableMoney);

        // Update for next iteration.
        _moneyNeededRemaining -= moneyToSubtractSinceLast;
        _lastSubtract = now;

        return moneyToSubtractSinceLast;
    }
}

public interface IAccount
{
    float AvailableMoney { get; set; }        
}