EAE 6320-001 GameEngII Game Engine Project, Game Dev Adventures!

Assignment 5: Human Editable Settings.ini and Lua for Graphics Building (and more…)

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The user can now set resolution via the settings.ini file. All shaders are now built with lua code. I also added some more pretty sprites. Hooray! (Simple one-click download. Once downloaded, unzip, play the executable, enjoy!)

About the Project

I added a settings.ini file to the download which allows users (like you!) to set the resolution of the game. The file is originally contained as part of the UserSettings project inside the engine, but is copied by Visual Studio into a predetermined output directory, and then the lua asset build script copies it into the final game directory. This is pretty neat as it makes updating the resolution practically trivial: meaning no code recompilation is needed. As everyone’s device is different, this allows the user to set their desired resolution. It also means that there is more we could add to the settings.ini file later that the user could then change as they desired, removing the developer from the updates at hand. As a developer, QA, or even level designer, this also makes it fast to test different resolutions for different platforms.

For gamers, hot loading data into the game takes the settings.ini idea a step further. Hot loading data into the game means (at least how I’ve done it) that game periodically checks for new data while it is running and can import the data during run-time. I actually prototyped a game at EA that did just this. So the player could drop a file specifying more data like having a dinosaur model in the game, put the information in the hotload folder, and then their dinasour would  appear in the game. It was really neat, especially as a player, to see data you created become part of the game during run-time.

Before the settings.ini (or the default resolution):

After a tweak to resolution variables in settings.ini:

The other thing I did was implement a lua script for building the graphics assets (and copying files into the final game directory). In debug I merely copy the lua build assets script which makes debugging and testing simpler. But in release the lua code is compiled and then ran. This makes running the lua code more efficient, but it also makes it hard to debug because, well, this:

It doesn’t really matter in this example though for compiling vs plain text as the assets build lua file is run at build time and so compiling the lua file only helps to build faster. It doesn’t affect the player.

Of course I didn’t compile the settings.ini file into binary because that would completely defeat the purpose of having a human-editable file for changing settings for the game. If a human can’t read it, they can’t edit it!

I find the interesting bugs…

So I ran into an interesting bug: I was getting an “incorrect function” error. It was obvious that there was a path error, but this error message was really throwing me off. After hours of trying to resolve (Zeno and my TA Ameya both helped me in trying to resolve the issue), but ultimately I was stuck. I finally talked with the developer (my professor) and he discovered a bug in his code: he was returning the wrong string variable for the error. Once that was resolved we quickly resolved my bug which to my chagrin was the same bug as his: I too was also returning the wrong string variable.

EAE 6320-001 GameEngII Game Engine Project, Game Dev Adventures!

Assignment 4: Utilizing Game and Render Threads for Improved Performance

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Now we’re getting somewhere! The game can now render an arbitrary amount of sprites per frame. In this instance there are four. I think it’s pretty. 😉 (Simple one-click download. Once downloaded, unzip, play the executable, enjoy!)

About the Project

The simplest part of this project was letting the game submit to the graphics a different background color. This data is cached until the renderer is ready to render.


I moved all the sprites and effects out of the graphics class and created them in the game. Because rendering takes a significant portion of time in games, we utilize threads to render while the game computes data. In this implementation the game submits to the render data it wants rendered, which is then cached by the renderer until it’s ready to render. When the game is done submitting it lets the render thread know. When the renderer has finished rendering all the previously submitted data it cleans up that data and let’s the game know when it can start submitting again. This is the point where the threads sync, which is done each frame. At sync the render thread swaps the submitted cache and the cache it just cleaned. It then uses this data to render, and the game has a clean cache to submit data too. Submitting to the render thread is simple, just send over the sprite with its corresponding effect:

eae6320::Graphics::SubmitToRender(m_sprite[0], m_effect[0]);

Each rectangle needs it’s own sprite, but an effect can be used multiple times. So the second sprite uses the same effect:

eae6320::Graphics::SubmitToRender(m_sprite[1], m_effect[0]);

I am using the stl’s vector to create as many (up to the maximum number that a vector can hold that is) sprites and effects as I want. It’s then fairly trivial to submit sprites and effects to be rendered to the render thread.

Even though we are passing reference pointers around for all the sprites and effects, since we can send an arbitrary amount of sprites and effects to render the memory overhead can get large if we haven’t optimized their size. I had previously optimized the sprite and effect size by ordering member variables from largest to smallest. However when I saw the sEffect size I realized I was passing around unnecessary data. I removed it and the size dropped by the size of the variables I removed.

sizeof(sSprite): 12
sizeof(sEffect): 24, 16

sizeof(sSprite): 24
sizeof(sEffect): 64, 48

I’d only ever looked at the size of objects via code, so it was interesting to me to look at it during compile time. I opened the Debug->Windows->Immediates window in Visual Studio, put in an obvious breakpoint and when the debugger paused, I typed in “sizeof(ObjectName)” and the immediates window printed it out. Thanks to Mark Smith for helping me find the Immediates window.

I am having a recurring Visual Studio run bug. I spent quite some time trying to resolve it. J.P. tried to help as well for a while with no luck. I finally reverted all our changes, closed VS, and rebuilt and the bug went away. The thing is that I’ve done this multiple times and it keeps coming back. Running and building in Visual Studio haunt me and give me terrible nightmares.

EAE 6320-001 GameEngII Game Engine Project, Game Dev Adventures!

Assignment 3: Graphics Platform Independence, User Input

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This game has TWO sprites with different effects! Aww, the awesomeness!

(Simple one-click download. Once downloaded, unzip, play the executable, enjoy!)

About the Project

In this project I made the graphics functions platform independent by creating a cView class. This class handled initializing, cleaning up, clearing, and presenting. Then all platform dependent code and variables went into cView.[platform].cpp files.

Thus the call for clearing the back buffer code now looks like this:

//When rendering

I used a color struct to pass colors, and used this to create the pretty gray background (as opposed to black).

sColor lightGray(0.8f, 0.8f, 0.8f);  //alpha is set to 1.0f when left blank
UpdateClearColor(lightGray);        //The UpdateClearColor can be called at anytime to update the clear color

To create a sprite I allowed the user to just send in a center position, width and height — as opposed to several vertices (Simplified):

eae6320::Graphics::VertexFormats::sSpriteVertex center1(0.0f, 0.5f);
sprite1.Initialize(center1, 0.5f, 0.5f);

To create an effect the user need only pass the name of the shader file to the effect:

eae6320::Graphics::sEffect effect1("shader1");

I also added a second sprite and effect so that I could draw in another sprite with different shader data.

Hmm… Interesting Error

We all got stumped on an interesting linker error I was getting early on when making the graphics code platform independent. I have no idea what caused it and it certainly didn’t feel interesting at the time as it sucked up a bunch of my time. I had actually given up on it for the night — I put in macros to the graphics.cpp and moved on to the rest of the game assignment — when finally after finishing the rest of the requirements I caught some problem solving determination, inspiration hit, and finally hit upon the solution: I did function renaming, code manipulation, and the last thing I did was I moved the included  Graphics.h header to be included before the <Engine/Results/cResult.h> header in my cView class. Once I swapped their positions it worked! I cleaned up the code, and then to test things, I moved it back and guess what: still worked! I couldn’t recreate the linker error. The problem was perhaps a couple things, and it’s possible I’ll never know where or what, but it does go to show you that with three friends, determination, and a cool head you can solve a problem, even if you don’t know the exact cause!

Getting it Done

I was initially stuck on deciding how to implement the platform independent graphics.cpp, but once I decided how it should be done the rest just kind of pounded out itself. That’s also about the time Arpit, Zeno, and I congregated and the work went faster, until it got really late, and then it slowed, but it was fun.

Thanks to Zeno and Arpit for helping all night. We helped each other through the entire project and there is no way I would have completed this on time without their help: there was a lot of help going around and everyone helped each other. Zeno is very knowledgeable: he really helped me with structures, architecture, and lots of random issues and C++ nitty gritty questions (It’s great discussing those c++ ideas with him). Arpit is very good at debugging: he helped me solve my shader errors and kept a cool head as I panicked. 🙂 Chen was helpful too: he stopped in for a bit and tried to help me resolve the aforementioned linker error. With everything they all had me try on that problem, it really helped me rule out what wasn’t wrong so that hours later I was finally able to fix it. I have some pretty cool peers.

I love what I do and I love that I get to work with such talented, intelligent, creative, and willingly helpful people. That’s the games industry! From my work at EA, in the EAE program, and in the serious game industry: I haven’t found a better group of incredibly competent, highly skilled people. I love my game dev peeps. They’re the best!

I feel tempted to do a hashtag: #OneLuckyGirl