Введение

Achievements can be used as a way to encourage and reward player interactions and milestones within your game. They are often used for marking number of kills, miles driven, chests opened or other common actions within your game. And they can also be used to help your players discover different ways of playing your game. When unlocked, these achievements will pop up in the corner of the players' window and will be marked within an achievement page for that player.

Technical Overview

The following is a quick step by step guide to integrating very basic Steam Achievements into your application in under 10 minutes and under 10 lines of code integrated into your code base. The Steamworks SDK comes with a great example application called Spacewar that shows off the full breadth of Steam features and should be your first stop to see all Steam features in action. This tutorial distills the information found in Spacewar and the Stats and Achievements API down to just the necessary information required for Steam Stats to keep things as straightforward as possible. Please note that there is a considerable amount of overlap between stats and achievements, as such if you are integrating both be aware that a lot of calls can be consolidated.

Step 1 - Defining your game's Achievements

Achievements are application specific and are setup on the Achievement Configuration page in the Steamworks App Admin backend. The following is the list of achievements from the Steamworks sample app Spacewar:

Step 2 - Encapsulating Achievements work

The following code is game independent and can be added to your game as you see fit. The class is fully functional as is but can be easily extended to meet any further needs. All of this code was taken directly from the Spacewar example files StatsAndAchievements.cpp/h.

Заголовочный файл

We first define a structure to hold our achievement data received from steam and provide a macro for creating objects of that type. This data maps directly to what is found on the Achievement Configuration page.

Next we define a helper class that will wrap all of the Steam Stats API calls as well as creating all of the Steam callbacks.

Программный код

Конструктор

Параметры - The constructor takes a pointer to an array of achievements along with the length of the array. The formating of that array will be covered in the main game code later.
Возвращаемые значения - N/A
Что делает - The constructor initializes a number of members along with grabbing the AppID we are currently running as. In addition it hooks up the call back methods to handle asynchronous calls made to Steam. Finally it makes an initial call to RequestStats() to get stats and achievements for the current user.

RequestStats()

Параметры - None
Возвращаемые значения — bool, показывающее, удался ли вызов. If the call failed then most likely Steam is not initialized. Make sure you have a steam client open when you try to make this call and that SteamAPI_Init has been called before it.
Что делает - This method basically wraps a call to ISteamUserStats::RequestCurrentStats which is an asynchronous call to steam requesting the stats and achievements of the current user. This call needs to be made before you can set any stats or achievements. The initial call to this method is made in the constructor. You can call it again any time after that if you want to check on updated stats or achievements.

SetAchievement()

Параметры - The string identifier of the Achievement that you want to set (ie. "ACH_WIN_ONE_GAME")
Возвращаемые значения - a bool representing if the call succeeded or not. If the call failed then either Steam is not initialized or you still haven't processed the callback from the initial call to RequestStats. You can't set any achievements until that callback has been received.
Что делает - This method sets a given achievement to achieved and sends the results to Steam. You can set a given achievement multiple times so you don't need to worry about only setting achievements that aren't already set. This is an asynchronous call which will trigger two callbacks: OnUserStatsStored() and OnAchievementStored().

OnUserStatsReceived()

Параметры — нет.
Возвращаемые значения — ничего.
Что делает - This method is a callback that is called anytime you attempt to request stats. Stats and achievements are requested by using RequestStats(). The method updates the member variable m_pAchievements to reflect the latest stats and achievement data returned from Steam.

OnUserStatsStored()

Параметры — нет.
Возвращаемые значения — ничего.
Что делает - This method is a callback that is called anytime you attempt to store stats on Steam.

OnAchievementStored()

Параметры - N/A
Возвращаемые значения - Nothing
Что делает - This method is a callback that is called anytime Achievements are successfully stored on Steam.

Step 3 - Integrating into your game

The following is a complete listing of code snippets that you would need to integrate into your game in the appropriate locations.

Определения и глобальные переменные

The following is the list of includes that are needed to build with Achievements, an enum of our game specific achievements and a global pointer to our helper object. Please note that the achievements match those of the Admin page on Steamworks.

Инициализация

The call to SteamAPI_Init initializes all of Steam and must be called before anything else. If that call succeeds then we create the helper object by passing in the array of achievements along with the size of the array.

Обработка обратных вызовов

To ensure that we process all Steam callbacks we need to regularly pump for new messages. This is achieved by adding this call to the game loop.

Активация достижений

Triggering an achievement is as simple as a single call passing along the achievement identifier.

Выключение SteamAPI

The call to SteamAPI_Shutdown is probably something you already have in your code. It shuts down steam and must be called before you application exits. Finally we delete the helper object we created.

Step 4 - Testing and Troubleshooting

To set or clear stats or an achievement without adding code to your game, you can use the Steam client console. Run with steam.exe -console, then:

• achievement_clear <appid> <achievement name>
  
• reset_all_stats <appid>