第四，我们坚持从头开始编写引擎，包括内存管理，渲染代码，动画等。我一直在使用的一些开放源码库包括：Bullet physics library，Lua以及SOIL（用于解压PNG纹理）。我之所以会坚持使用这些源码库是因为我希望借此学习如何创建一个能够与不同模块相互作用的引擎。并且，我也不擅长物理和脚本语言，所以如果要自己编写物理库和脚本语言将会花费更多时间，并且最终创造出来的代码可能也没有Bullet或Lua那般有效。所以我便选择了具有源代码的开放源码库，从而帮助我更轻松地进行调试。
Writing an iPhone Game Engine (Part 7- Postmortem)
The first game that made with the iPhone game engine described in this series is released before Christmas on App Store, it is called Monster Bowling.
You may surprise that the final product is different from the screen shots shown before which is an adventure game that controlling a ship to explore the world. This is because someone in that project lost his passion and the production of that game has been stopped. And I do not want to waste my effort on making an engine without producing any game, so I decided to work with another artist which resulted in Monster Bowling. The engine and tools took me 9 months to write and the game code took me another 6 months of spare time to complete, which is quite a long time…
What we did wrong
Here I will summarize what mistake we have taken in these 2 projects.
First, the ship game project failed because the scale of the game is too big. Although some of the content is cut during production, there are still too many things need to take care and the team member gradually lose their passion about the game. So, my advice of making a game in spare time, especially when you work with other people the first time, is don’t try to make a big game. If anyone in the team lose their passion, the game will never get shipped no matter how hard you work.
Second, the other reason why the ship game failed because there is no a clear direction in the team, how the game project should progress and a clear schedule and check list what should be done. Without a direction, the team member will easily get lost and lost their passion.
Third, this point is about the released game Monster Bowling. When the game was just released, the sales was not good. It is because within this team, there is only 1 artist and 1 programmer, both were putting most of their effort on developing the game and didn’t pay much attention to marketing the game and let the public know about the game. So when the game was just released, there didn’t have any game review to boost the sales up.
Fourth, this point is about technical issue within the engine. Within the engine, both the game runtime and the editors use the same file format which is a binary format. But doing in this way resulted in a problem which cannot merge the files, for example, when the game objects within a game level are modified by 2 people, we are not able to merge the changes. Luckily, as our team is small, we just do not edit the same file at the same time which does not cause a great trouble in the project.
What we did right
After talking about the mistakes, I will talk about some decisions that I think is made correctly.
First, during the production of Monster Bowling, there are constant communication within the team. We talked about the progress of the game every 1 or 2 weeks. This is very important for those who make games in their free time because through talking about the game, we can keep the passion and let other team member know what are going on in the project.
Second, the decision of making editors and Mac version of the game is important. This enable artist to build and test the game level without any programmer interaction. Although the editors are not user friendly, the artist would suggested to add the minimal set of features (e.g. adding zoom extend to objects in the 3D viewport) that he can live with so that he can work in a much faster way. Explicitly saying what features are lacking will help the programmer to improve the tools.
Level editor used to build the game
Third, embedding a scripting language to the game engine is useful. Writing game play code in Lua is much faster than using C++. Also modifying the script file is much faster than compiling C++ code which can have a faster iteration time. Also scripting language can draw a clear separation between engine code and game play code. Thanks to Lua, when migrating from the ship project to Monster Bowling, there does not have much to change in the engine code.
Test level of Monster Bowling which built using Lua
Fourth, as the engine is written from scratch starting from memory management, rendering code, animation. I still use some open source library: Bullet physics library, Lua and SOIL (for decompressing PNG texture). I use them because my goal is to learn how an engine should be architected to interact with different modules. Also I am not strong at physics and scripting, writing my own physics library and scripting language will take a long time and the code would not be as fast as Bullet and Lua. So I choose to use some open source library which have source code so that it is easier to debug.
This iPhone game engine project took a total of 1 year and 3 months of spare time to complete and produced 1 game. As there is only 1 programmer, Some open source library are used and I decided to sacrifice my favorite graphics programming(the engine doesn’t perform lighting and using texture color only) to keep the work load low. I think that it is ridiculous to write an engine without making any game, so I worked on Monster Bowling using this engine, but there are some effort is wasted (i.e. world level streaming) when migrating from the ship project. So if someone just want to focus on making games only, I would suggest they license a commercial engine such as Unity or UDK rather than writing their own engine which will cost a large amount of time. But for me, writing my own engine is to learn and most important is for fun.(source:altdevblogaday)