84ac4a40c1
The current way "arrays" from XML files are loaded (before this commit
is applied) goes something like this:
1. Read the buffer of the contents of the tag using TinyXML-2.
2. Allocate a buffer on the heap of the same size, and copy the
existing buffer to it. (This is what the statement `std::string
TextString = pText;` does.)
3. For each delimiter in the heap-allocated buffer...
a. Allocate another buffer on the heap, and copy the characters from
the previous delimiter to the delimiter you just hit.
b. Then allocate the buffer AGAIN, to copy it into an std::vector.
4. Then re-allocate every single buffer YET AGAIN, because you need to
make a copy of the std::vector in split() to return it to the caller.
As you can see, the existing way uses a lot of memory allocations and
data marshalling, just to split some text.
The problem here is mostly making a temporary std::vector of split text,
before doing any actual useful work (most likely, putting it into an
array or ANOTHER std::vector - if the latter, then that's yet another
memory allocation on top of the memory allocation you already did; this
memory allocation is unavoidable, unlike the ones mentioned earlier,
which should be removed).
So I noticed that since we're iterating over the entire string once
(just to shove its contents into a temporary std::vector), and then
basically iterating over it again - why can't the whole thing just be
more immediate, and just be iterated over once?
So that's what I've done here. I've axed the split() function (both of
them, actually), and made next_split() and next_split_s().
next_split() will take an existing string and a starting index, and it
will find the next occurrence of the given delimiter in the string. Once
it does so, it will return the length from the previous starting index,
and modify your starting index as well. The price for immediateness is
that you're supposed to handle keeping the index of the previous
starting index around in order to be able to use the function; updating
it after each iteration is also your responsibility.
(By the way, next_split() doesn't use SDL_strchr(), because we can't get
the length of the substring for the last substring. We could handle this
special case specifically, but it'd be uglier; it also introduces
iterating over the last substring twice, when we only need to do it
once.)
next_split_s() does the same thing as next_split(), except it will copy
the resulting substring into a buffer that you provide (along with its
size). Useful if you don't particularly care about the length of the
substring.
All callers have been updated accordingly. This new system does not make
ANY heap allocations at all; at worst, it allocates a temporary buffer
on the stack, but that's only if you use next_split_s(); plus, it'd be a
fixed-size buffer, and stack allocations are negligible anyway.
This improves performance when loading any sort of XML file, especially
loading custom levels - which, on my system at least, I can noticeably
tell (there's less of a freeze when I load in to a custom level with
lots of scripts). It also decreases memory usage, because the heap isn't
being used just to iterate over some delimiters when XML files are
loaded.
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| .. | ||
| src | ||
| .dockerignore | ||
| .gitignore | ||
| CMakeLists.txt | ||
| CONTRIBUTORS.txt | ||
| Dockerfile | ||
| README.md | ||
| version.cmake | ||
How to Build
VVVVVV's official desktop versions are built with the following environments:
- Windows: Visual Studio 2010
- macOS: Xcode CLT, currently targeting 10.9 SDK
- GNU/Linux: CentOS 7
The engine depends solely on SDL2 and SDL2_mixer. All other dependencies are statically linked into the engine. The development libraries for Windows can be downloaded from their respective websites, Linux developers can find the dev libraries from their respective repositories, and macOS developers should compile and install from source (including libogg/libvorbis/libvorbisfile).
Steamworks support is included and the DLL is loaded dynamically, you do not need the SDK headers and there is no special Steam or non-Steam version. The current implementation has been tested with Steamworks SDK v1.46.
To generate the projects on Windows:
# Put your SDL2/SDL2_mixer folders somewhere nice!
mkdir flibitBuild
cd flibitBuild
cmake -G "Visual Studio 10 2010" .. -DSDL2_INCLUDE_DIRS="C:\SDL2-2.0.10\include;C:\SDL2_mixer-2.0.4\include" -DSDL2_LIBRARIES="C:\SDL2-2.0.10\lib\x86\SDL2;C:\SDL2-2.0.10\lib\x86\SDL2main;C:\SDL2_mixer-2.0.4\lib\x86\SDL2_mixer"
Note that on some systems, the SDL2_LIBRARIES list on Windows may need
SDL2/SDL2main/SDL2_mixer to have .lib at the end of them. The reason for this
inconsistency is unknown.
To generate everywhere else:
mkdir flibitBuild
cd flibitBuild
cmake ..
macOS may be fussy about the SDK version. How to fix this is up to the whims of however Apple wants to make CMAKE_OSX_SYSROOT annoying to configure and retain each time Xcode updates.
Including data.zip
You'll need the data.zip file from VVVVVV to actually run the game! It's available to download separately for free in the Make and Play edition of the game. Put this file next to your executable and the game should run.
This is intended for personal use only - our license doesn't allow you to actually distribute this data.zip file with your own forks without getting permission from us first. See LICENSE.md for more details. (If you've got a project in mind that requires distributing this file, get in touch!)
A Word About Compiler Quirks
(Note: This section only applies to version 2.2 of the source code, which is the initial commit of this repository. Since then, much hard work has been put in to fix many undefined behaviors. If you're compiling the latest version of the source code, ignore this section.)
This engine is super fussy about optimization levels and runtime checks. In particular, the Windows version absolutely positively must be compiled in Debug mode, with /RTC enabled. If you build in Release mode, or have /RTC disabled, the game behaves dramatically different in ways that were never fully documented (bizarre softlocks, out-of-bounds issues that don't show up in tools like Valgrind, stuff like that). There are lots of things about this old code that could be cleaned up, polished, rewritten, and so on, but this is the one that will probably bite you the hardest when setting up your own build, regardless of platform.
We hope you'll enjoy messing with the source anyway!
Love, flibit