Native Extensions


#121

hug

What about ios/android?


#123

Yeah, I didn’t have time to try out any other platforms. I’ll post some numbers on iOS/Android next week I hope (If I don’t forget it :wink: ).


#124

Ok, some more numbers (in bytes).
First off, comparing some platforms:

OSX + iOS + Android

  • Stripped
  • Removed: Physics + Record
4111380 dmengine
3061760 dmengine_opt

3006220 ios_dmengine_64
2670316 ios_dmengine_64_opt

3398552 libdmengine.so
2718520 libdmengine_opt.so

iOS

  • Stripped
  • 64 bit exe only
  • Removed: Physics + Record + Facebook
  • Different -O* flags for object files
3006220 ios_dmengine_orig
2171684 ios_dmengine_O2_opt
1993980 ios_dmengine_O1_opt
1961532 ios_dmengine_Os_opt
1862388 ios_dmengine_Os_NDEBUG_opt # with define NDEBUG

In this test, I haven’t removed the builtin debug app, of which the embedded data file is ~185kb which also would be nice to get rid of.

Still, a way to go before reaching our 1mb dream goal, but still… it is good to be able to shave off some bytes every now and then :wink:


#125

While on mobile platforms this is not so noticeable as the overhead reductions are tiny compared to total app size, it is good to allow memory to be optimized. I guess performance doesn’t change because those modules should be run only if in use.

This will be brilliant on HTML where each extra MB is about 1 second of wait time for the load.


#126

One of the goals is of course to make the html5 engine as small and fast as possible. And, a smaller executable will also load faster on any platform.


#127

The Linux support is progressing, although it (again) got side tracked by a bunch of things this sprint too ^^
But once I got to actually sit down with it, it came together nicely. Now I need to clean up some code etc. and do more testing.
It won’t make it into the 1.2.115 1.2.116 release, but should be in the next one after that.

Here’s a small preview:

Another thing that will be in next sprint is the improved app manifest support, that will allow you to add or remove (some) libraries that you might want (or not). E.g. to build a release or headless build, or remove physics and/or facebook…


#128

@ChristianM was curious on the numbers of the HTML5 build too, so I started doing the same for that platform too.
While looking at the numbers, we started discussing more and more things we wanted to remove or try removing.
A classic, it’s just too fun to not start optimizing a bit while at it ^^

Here’s the bigger things I did:

  • ndebug means I compiled with -DNDEBUG. It removes the asserts() and the strings they contain. It also removes various amounts of debug code.
  • <libname> means I removed that lib or functionality. Either statically, or using the app manifest.
  • I removed the logging macros, and profile, debug rendering and the built in Connect App from dmengine_release. This should save ~200kb for each platform in the release build
  • After building, I gzipped the custom built dmengine.js from the native extension build
1328132 dmengine.js.tar.gz -- original
1129375 dmengine_physics.js.tar.gz
1078882 dmengine_ndebug_physics.js.tar.gz
1051503 dmengine_ndebug_physics_log.js.tar.gz
 899918 dmengine_log_physics_dbgrender_profile_builtins.js.tar.gz
 890807 dmengine_log_physics_dbgrender_profile_builtins_facebook.js.tar.gz
 859237 dmengine_ndebug_log_physics_render_builtins.js.tar.gz

Using gzip -9 instead of tar (which I should have done from the start):

 877437 dmengine_gzip9_log_physics_render_profile_builtins_facebook.js.tar.gz
 846926 dmengine_gzip9_ndebug_log_physics_render_builtins.js.tar.gz

The NDEBUG option shaves off an extra ~30, but that also means we internally have to update more
on our build system side (and on the Native Extension server), so that will have to come a little later. There are easier things to do first.

I feel confident that the executable can be even smaller. We have a few other options to explore that will take various amounts of time to implement. Both in general, but also depending on what features you actually need.

Hopefully, this added functionality should land in a release soon :slight_smile:

EDIT:
Here are numbers on some of the source .js files I compressed for the test:

5736253 dmengine_original.js
4884828 dmengine_physics.js
4437975 dmengine_ndebug_physics_log.js
4139089 dmengine_log_physics_dbgrender_profile_builtins.js
4096556 dmengine_log_physics_dbgrender_profile_builtins_facebook.js
3821933 dmengine_ndebug_physics_log_builtins.js
3615977 dmengine_ndebug_log_physics_dbgrender_builtins.js

#129

wait… that is UNDER a meg! I smell instant games here =]
So putting the engine on a diet seems to be fun :stuck_out_tongue:


#130

A quick note on supporting multiple platforms in your extensions.

When supporting cross platform code, I often use one of these tricks to catch “errors”.

Compile error

If I don’t support a certain platform, and if there is no reason or good way to hide it. I make sure that I get a clear error message when compiling:

#if defined(DM_PLATFORM_IOS) || defined(DM_PLATFORM_ANDROID)
    // my working code
#else
    #error "Platform not supported for this extension!"
#endif

Imho, it’s a LOT clearer than error LNK2019: unresolved external symbol <symbol> referenced in function...

Adding a “null” implementation

Sometimes is feels “nicer” to add a dummy, non working or mock implementation for those platforms not supported:

#if defined(DM_PLATFORM_IOS) || defined(DM_PLATFORM_ANDROID)
    // my working code
#else
// for the rest of the unsupported platforms
static dmExtension::Result AppInitializeExtension(dmExtension::AppParams* params)
{
    dmLogWarning("Registered %s (null) Extension\n", MODULE_NAME);
    return dmExtension::RESULT_OK;
}

static dmExtension::Result InitializeExtension(dmExtension::Params* params)
{
    return dmExtension::RESULT_OK;
}

static dmExtension::Result AppFinalizeExtension(dmExtension::AppParams* params)
{
    return dmExtension::RESULT_OK;
}

static dmExtension::Result FinalizeExtension(dmExtension::Params* params)
{
    return dmExtension::RESULT_OK;
}

#endif

DM_DECLARE_EXTENSION(EXTENSION_NAME, LIB_NAME, AppInitializeExtension, AppFinalizeExtension, InitializeExtension, 0, 0, FinalizeExtension);

These two tricks will save yourself (and others) a lot of development and debugging time!


Look Your Loot aka Hamster
#131

Agree. I use the dummy module approach, where I assign each function a stub print message.

#ifndef DM_PLATFORM_ANDROID
#ifndef DM_PLATFORM_IOS

#include <dmsdk/sdk.h>
#include "extension.h"

static int stub(lua_State *L) {
	dmLogInfo(EXTENSION_NAME_STRING " extenstion is not supported on this platform.");
	return 0;
}

dmExtension::Result APP_INITIALIZE(dmExtension::AppParams* params) {
	return dmExtension::RESULT_OK;
}

dmExtension::Result APP_FINALIZE(dmExtension::AppParams* params) {
	return dmExtension::RESULT_OK;
}

dmExtension::Result INITIALIZE(dmExtension::Params* params) {
	const luaL_Reg lua_functions[] = {
		{"enable_debug", stub},
		{"init", stub},
		{"show_banner", stub},
		{"remove_banner", stub},
		{"load_interstitial", stub},
		{"show_interstitial", stub},
		{"is_interstitial_ready", stub},
		{"load_video", stub},
		{"show_video", stub},
		{"is_video_ready", stub},
		{"load_rewarded_video", stub},
		{"show_rewarded_video", stub},
		{"is_rewarded_video_ready", stub},
		{"load_offerwall", stub},
		{"show_offerwall", stub},
		{"is_offerwall_ready", stub},
		{"load_more_apps", stub},
		{"show_more_apps", stub},
		{"is_more_apps_ready", stub},
		{"load_native", stub},
		{"get_native", stub},
		{"is_native_ready", stub},
		{"native_trigger_display", stub},
		{"native_trigger_click", stub},
		{NULL, NULL}
	};

	luaL_openlib(params->m_L, EXTENSION_NAME_STRING, lua_functions, 1);
	return dmExtension::RESULT_OK;
}

dmExtension::Result UPDATE(dmExtension::Params* params) {
	return dmExtension::RESULT_OK;
}

dmExtension::Result FINALIZE(dmExtension::Params* params) {
	return dmExtension::RESULT_OK;
}

DECLARE_DEFOLD_EXTENSION

#endif
#endif

#132

Can you add some instruction about engine customization(stripping)? Which libs supports and so on, pls!


#133

Of course!
I got so excited about the release I had forgot to prepare my notes… ^^

Customizing the engine build

Apart from specifying your own new extensions, you can also enable/disable libraries via the "App Manifest"
This is a feature that has very little documentation yet (none?).
The basic idea is that it should work very closely to how the extension manifest works (and also our master config for the server).
And although this config design isn’t fully nailed down, we think it’s beneficial your you to get access to this alpha feature so you can
start playing with it (or release with it!).

Config

There are a few new keywords, in perticular: excludeLibs, excludeSymbols, excludeJars which allow you to remove libraries and C++ symbols and also .jar files.
Using the libs keyword, you can add engine libraries, and using symbols you can add engine symbols

Future

Currently, there are not a whole lot of options for you to play with, and to be honest, we’d like to improve on this a lot.
It’s not extremely user friendly to modify a build like this. We’d like more.
What we’d like, is to categorize the engine into more extensions (or features), and allow you to select those features you actually need.
Or, perhaps we could detect this as well: removing components or script modules you don’t use.

How to

Below, you’ll find the three most asked for build variants.
Enabling these is straightforward, albeit a little hiddeen:

  1. Copy an app manifest file to your project (e.g. game_nophysics.appmanifest)
  2. Add a reference to it in your game.project file (edit it as text)
[native_extension]
app_manifest = /game_nophysics.appmanifest
  1. Build or bundle!

Example files

game_release.appmanifest :

# Release build
platforms:
    x86_64-linux:
        context:
            excludeLibs: ["engine"]
            libs: ["engine_release"]

    x86_64-osx:
        context:
            excludeLibs: ["engine"]
            libs: ["engine_release"]

    js-web:
        context:
            excludeLibs: ["engine"]
            libs: ["engine_release"]

    x86-win32:
        context:
            excludeLibs: ["libengine"]
            libs: ["libengine_release.lib"]

    x86_64-win32:
        context:
            excludeLibs: ["libengine"] 
            libs: ["libengine_release.lib"]

    armv7-android:
        context:
            excludeLibs: ["engine"]
            libs: ["engine_release"]

    armv7-ios:
        context:
            excludeLibs: ["engine"]
            libs: ["engine_release"]
            
    arm64-ios:
        context:
            excludeLibs: ["engine"]
            libs: ["engine_release"]

game_headless.appmanifest :

# Release build
platforms:
    x86_64-linux:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null"]

    x86_64-osx:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null"]

    js-web:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null"]

    armv7-android:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null"]

    armv7-ios:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null"]
            
    arm64-ios:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null"]

    x86-win32:
        context:
            excludeLibs: ["libgraphics", "libsound", "librecord", "libvpx", "libtremolo", "libhid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["libgraphics_null.lib","libsound_null.lib", "librecord_null.lib", "libhid_null.lib"]

    x86_64-win32:
        context:
            excludeLibs: ["libgraphics", "libsound", "librecord", "libvpx", "libtremolo", "libhid"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["libgraphics_null.lib","libsound_null.lib", "librecord_null.lib", "libhid_null.lib"]
            

game_nophysics.appmanifest :

# Release + No: Physics + Record + Profiler
platforms:
    x86_64-osx:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics", "record", "vpx", "engine", "profilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["engine_release", "physics_null", "record_null"]

    x86_64-linux:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics", "record", "vpx", "engine", "profilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["engine_release", "physics_null", "record_null"]

    js-web:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics", "record", "vpx", "engine", "profilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["engine_release", "physics_null", "record_null"]

    x86-win32:
        context:
            excludeLibs: ["libBulletDynamics", "libBulletCollision", "libLinearMath", "libBox2D", "libphysics", "librecord", "libvpx", "libengine", "libprofilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["libengine_release.lib", "libphysics_null.lib", "librecord_null.lib"]

    x86_64-win32:
        context:
            excludeLibs: ["libBulletDynamics", "libBulletCollision", "libLinearMath", "libBox2D", "libphysics", "librecord", "libvpx", "libengine", "libprofilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["libengine_release.lib", "libphysics_null.lib", "librecord_null.lib"]

    armv7-android:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics", "record", "vpx", "engine", "profilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["engine_release", "physics_null", "record_null"]

    armv7-ios:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics", "record", "vpx", "engine", "profilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["engine_release", "physics_null", "record_null"]
            
    arm64-ios:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics", "record", "vpx", "engine", "profilerext"]
            excludeSymbols: ["FacebookExt", "ProfilerExt"]
            libs: ["engine_release", "physics_null", "record_null"]
            

EDIT: Upon request, here is a headless release config as well.

game_headless_release.appmanifest:

# Release build
platforms:
    x86_64-linux:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid", "engine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null", "engine_release"]

    x86_64-osx:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid", "engine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null", "engine_release"]

    js-web:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid", "engine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null", "engine_release"]

    armv7-android:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid", "engine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null", "engine_release"]

    armv7-ios:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid", "engine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null", "engine_release"]
            
    arm64-ios:
        context:
            excludeLibs: ["graphics", "sound", "record", "vpx", "tremolo", "hid", "engine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["graphics_null","sound_null", "record_null", "hid_null", "engine_release"]

    x86-win32:
        context:
            excludeLibs: ["libgraphics", "libsound", "librecord", "libvpx", "libtremolo", "libhid", "libengine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["libgraphics_null.lib","libsound_null.lib", "librecord_null.lib", "libhid_null.lib", "libengine_release.lib"]

    x86_64-win32:
        context:
            excludeLibs: ["libgraphics", "libsound", "librecord", "libvpx", "libtremolo", "libhid", "libengine"]
            excludeSymbols: ["DefaultSoundDevice", "AudioDecoderWav", "AudioDecoderStbVorbis", "AudioDecoderTremolo"]
            libs: ["libgraphics_null.lib","libsound_null.lib", "librecord_null.lib", "libhid_null.lib", "libengine_release.lib"]
            

I hope this will at least get you started! We will add proper docs soon! :slight_smile:


Is Defold can really make small size Android APK?
Dmengine headless release (DEF-3002)
State of Extensions for mobile?
Is Defold can really make small size Android APK?
Compiling native extension lib for Windows
Defold on Instant Games
#134

Good point! I believe I’m failing in this area in some of my extensions. I’ll take a look at this tomorrow.


#135

One issue that will arise more and more regarding adding extensions, is getting link errors due to duplicate symbols. This is not an uncommon problem but it’s fairly easy to remedy if you have full access to all steps in a compile pipeline.

However, since this isn’t possible in a closed system, we have to use other means to resolve it.

Currently, the engine only has a few composite libraries, which include parts of other libs (e.g. some crypto functions). This makes it impossible to remove “just that part” from the engine. Instead, you’ll have to instead rename your incoming symbols. In effect, you have to rename all colliding functions in that library, and recompile that library before using it. A common trick is to rename from “apiFunction()” to “apiFunction2()”, and then you use apiFunction2() in your code.

Of course, that means more work for you users, and we want to make it easier, so we are going to look into splitting our larger libraries, so you can exclude more parts of it, in favor of your new(er) versions.


#136

Is it possible to use two different appmanifest:
one for release build and other for debiug build?


#137

The easiest way is probably to do it in your build script. Very simple to do in python for example

f = "path/to/game.project"
config = configparser.ConfigParser()
config.read(f)
config.set("project", "title", "DEBUG_TITLE")

with open(f, "w") as fp:
    config.write(fp)

#138

I tried stripping only the physics out to see the implications on memory and package size. May as well dump my findings here.

Because I didn’t want to spend too much time I only tested on macOS builds, the memory could differ from device to device though so keep that in mind. I built each version for macOS and got the memory with profiler.get_memory_usage(). I restarted the whole game after each sample and I used 9 samples. Testes done with engine version 1.2.117 and in release mode.

TLDR; The package size decrease is nice but memory implication is pretty meh.

appmanifest
# Release + No: Physics
platforms:
    x86_64-osx:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics"]
            libs: ["engine_release", "physics_null"]
 
    x86_64-linux:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics"]
            libs: ["engine_release", "physics_null"]
 
    js-web:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics"]
            libs: ["engine_release", "physics_null"]
 
    x86-win32:
        context:
            excludeLibs: ["libBulletDynamics", "libBulletCollision", "libLinearMath", "libBox2D", "libphysics"]
            libs: ["libengine_release.lib", "libphysics_null.lib"]
 
    x86_64-win32:
        context:
            excludeLibs: ["libBulletDynamics", "libBulletCollision", "libLinearMath", "libBox2D", "libphysics"]
            libs: ["libengine_release.lib", "libphysics_null.lib"]
 
    armv7-android:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics"]
            libs: ["engine_release", "physics_null"]
 
    armv7-ios:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics"]
            libs: ["engine_release", "physics_null"]
             
    arm64-ios:
        context:
            excludeLibs: ["BulletDynamics", "BulletCollision", "LinearMath", "Box2D", "physics"]
            libs: ["engine_release", "physics_null"]

Memory

Data of an empty project, with physics

Empty 5 Collections from file 5 Collection Proxies 5 Collection Proxies - Loaded
Average MB 38.9 38.8 38.7 40.5
Average Bytes 38884693 38763633 38673066 40482588

The data collected indicates that each collection proxy adds 0.36 MB of memory.

Data of an empty project, without physics

Empty 5 Collections from file 5 Collection Proxies 5 Collection Proxies - Loaded
Average MB 38.6 38.4 38.6 40.2
Average Bytes 38600704 38420024 38642574 40194048

Interestingly the data we get now for 5 collection proxies loaded is 1MB lower compared to having it with physics, but it is also still 1.8 MB over the other values. The memory added per collection is 0.36, meaning a 0.09 difference between with and without physics.

Package size

With Without Diff Diff -MB
Android 2801489 2491918 -309571 -0.3
iOS 2619459 2263253 -356206 -0.35
macOS 5408039 4230099 -1177940 -1.2

Other observations

profiler.get_memory_usage() is broken, doesn’t indicate that memory is released and only counts up. Making it only really reliable on build/app start.

If you have physics objects in your build and strips physics out the build will not be able to start but will not give any errors as far I noticed.

I should (but most likely won’t) test it out on android and/or iPhone to investigate if it is comparable with macOS.


#139

Prompted by the other thread I made a github repo with the existing appmanifest files for easy access and to collect others made over time.

I will do some tests too to collect data and create other useful appmanifest files.


#140

Or may be these could be also useful if put to the docs?
Summoning @sicher in case he has an opinion =]


#141

I have a couple little questions/clarifications regarding appmanifest options:

  1. By default, are both 3D and 2D physics engines included in all projects?
    If yes, I guess it makes sense for all 2D projects to exclude 3D physics, and vice versa, so…

  2. Which libs correspond to 3D physics, 2d physics, or both?

    • 2a. I assume “BulletDynamics” and “BulletCollision” for 3D physics and “Box2D” for 2D?
    • 2b. What about “LinearMath” and “physics”?
  3. “vpx” is just for the built-in video recorder, right?