Great news!
The Learn OpenGL ES website recently switched its licensing to Creative Commons BY-SA 3.0 
http://www.learnopengles.com/announcing-the-new-qa-and-forums-and-a-roundup/
It provides tutorials for OpenGL ES using Java/Android and WebGL, and is focusing on a more community-oriented creative process. Give them cheers!
Meritous is a nice, addictive action-adventure dungeon crawl game. Each new game is unique since the dungeon is built in a semi-random fashion. Last but not least, the engine, graphics and sound effects are GPL'd
The game is based on SDL 1.2, which has an unofficial Android variant, so I decided to try and port it on my cell phone!
The port was surprinsingly smooth and only non-SDL fixes (move big stack allocation to heap) were necessary.
Who said it was difficult to program in C on Android? 
It was also an opportunity to study the build system for F-Droid, an app market for free software apps, where APKs are rebuilt from source. The spec-like file is here.
The game packaging is also being ressurected for Debian but is being distressfully held hostage in the NEW queue for 2 weeks!
You can download the very first (aka beta) Android version:
Comments welcome!
The OpenGL ES port of FreeGLUT is progressing
Now we have:
Basic Android/EGL port
Full X11/EGL port (using Mesa EGL), so we can test GLES on desktop
Geometry functions: upgrade from glBegin to glVertexPointer and GLES compatibility (triangulation). We also plan to provide shaders-compatible (OpenGL >= 2) geometry functions.
In addition, the work is available in the official repository! http://freeglut.svn.sourceforge.net/viewvc/freeglut/trunk/freeglut/freeglut/
Question: Mesa and Android ship GLES 1&2 in separate libraries. So at first glance, we'll have to ship 3 FreeGLUT builds:
freeglut.so / .a
freeglut-gles2.so / .a with -DFREEGLUT_GLES2 (-lGLESv2 + GLES2/gl2.h)
freeglut-gles1.so / .a with -DFREEGLUT_GLES1 (-lGLESv1_CM + GLES/gl.h)
Though, EAGL (on iPhone) can initialize either GLES 1 or 2 at run-time. Maybe it's possibly to do that by dlopen'ing the GLES library dynamically, but this won't work for static builds - and make distro packagers cringe unless I'm mistaken
Do you think there's a way to provide a unified version?
I'm working on porting FreeGLUT for Android, and FreeGLUT is switching to CMake.
I'm more familiar with the GNU Autotools myself, and I'm used to cross-compile with a simple:
./configure --host=arm-linux-androideabi
Can we do that with CMake? Well, it's not well-documented, but yes :) Let's see how to do that for Android (smartphones) and MinGW (.exe for windows).
The principle is:
write a "toolchain" CMake script that defines the cross-compiler,
mention you're using a "GNU" compiler (a.k.a. GCC) so CMake automatically looks for prefixed cross-compilers tools such as
arm-linux-androideabi-cpporarm-linux-androideabi-ld.pass the toolchain script to CMake using the predefined
CMAKE_TOOLCHAIN_FILEvariable.REMOVE all the CMake-generated files when you change anything, CMake does not rebuild its cache when the toolchain script or PATH is modified, this creates misleading errors. Hence, building in a subdirectory is crucial.
Here's a simple toolchain script:
SET(CMAKE_SYSTEM_NAME Linux) # Tell CMake we're cross-compiling include(CMakeForceCompiler) # Prefix detection only works with compiler id "GNU" # CMake will look for prefixed g++, cpp, ld, etc. automatically CMAKE_FORCE_C_COMPILER(arm-linux-androideabi-gcc GNU) SET(ANDROID TRUE)
Note: SET(ANDROID TRUE) is not mandatory for CMake, it's just used to detect an Android build in the particular case of FreeGLUT development.
Here's how to invoke it:
PATH=/usr/src/ndk-standalone-9/bin:$PATH cd /usr/src/freeglut-3.0.0/ mkdir cross-android/ && cd cross-android/ cmake \ -D CMAKE_TOOLCHAIN_FILE=../android_toolchain.cmake \ -D CMAKE_INSTALL_PREFIX=/freeglut \ .. make -j4 make install DESTDIR=$(pwd)
Now here's a slightly more complex toolchain for MinGW.
The main issue with MinGW is that there are at least 4 possible prefixes depending on which version and which distro you're using. So I ask the user to specify it with GNU_HOST:
SET(CMAKE_SYSTEM_NAME Windows) include(CMakeForceCompiler) IF("${GNU_HOST}" STREQUAL "") SET(GNU_HOST i586-mingw32msvc) ENDIF() # Prefix detection only works with compiler id "GNU" CMAKE_FORCE_C_COMPILER(${GNU_HOST}-gcc GNU) # CMake doesn't automatically look for prefixed 'windres', do it manually: SET(CMAKE_RC_COMPILER ${GNU_HOST}-windres)
I wanted to print an error when GNU_HOST is not specified, but the toolchain script is loaded multiple times, and the command-line variables are not always set (CMake is not super-clean in that regard). So I defined a default, that works.
Sample invocation:
apt-get install mingw-w64 mkdir cross-woe/ && cd cross-woe/ cmake \ -D GNU_HOST=x86_64-w64-mingw32 \ -D CMAKE_TOOLCHAIN_FILE=../mingw_cross_toolchain.cmake \ -D CMAKE_INSTALL_PREFIX=/freeglut \ .. make -j4 make install DESTDIR=$(pwd)
I used this technique to cross-compile my projects, or other projects that use CMake. mingw-cross-env uses this technique (abeilt with explicit definition of all compiler tools) to provide pre-built windows libraries without altering the existing CMake scripts.
Do you people have tips or a better technique to cross-compile with CMake?
Today, there were events all around Europe to block ACTA.
In Paris, the protest started at Place de la Bastille :
APRIL was present, with in particular its president Lionel Allorge, and two members who wore the traditional anti-DRM suit :
Jérémie Zimmermann from La Quadrature du Net gave a speech and urged people to contact their legal representatives, in addition to protesting in the street :
The protest was cheerful and free of violence :
It got decent media coverage :
Notable places it crossed include Place des Victoires :
and Palais Royal, where it ended :
Next protest is in 2 weeks, on March 10th. Update your agenda!
I recently faced an environment where there is no MTA.
WTF? The reason is that people who work there get security audits on a regular basis, and the security people are usually mo...deratly skilled guys who blindly run a set of scripts, e.g. by ordering to disable Apache modules that "where seen enabled in /etc/apache2/mods-available/"...
To avoid spending days arguing with them and nitpicking with non-technical managers, the system is trimmed to the minimum - and there is no MTA. No MTA, so no cron output, so difficulty to understand why last night's cron job failed miserably.
Since it was not my role to reshape the whole business unit, I decided to hack a super-light, but functional way to get my cron output:
cat <<'EOF' > /usr/sbin/sendmail
#!/bin/bash
(
echo "From me $(LANG=C date)"
cat
echo
) >> /var/mail/all
EOF
chmod 755 /usr/sbin/sendmail
It works!
There is a companion logrotate script, to avoid filling the file system:
cat <<'EOF' > /etc/logrotate.d/mail-all
/var/mail/all {
daily
rotate 10
compress
delaycompress
notifempty
create 622 root mail
}
EOF
Bootstrap with:
touch /var/mail/all
logrotate -f /var/mail/all
You now can check your sys-mails with:
mutt -f /var/mail/all
I'm working on porting FreeGLUT to Android!
Since I don't have access so the repository (I'm not a regular contributor), and since it will be a BIG patch, I thought I'd try a git-svn branch. So this won't be a post on OpenGL for once
I'm not an expert at managing Git branch but here's how I set it up.
In this case, let's forget about importing tags: they don't have the same directory branch point in the hierarchy (sometimes the freeglut/ module, sometimes the parent directory), and git-svn only correctly supports set of sane tags that track the same initial directory.
SVN is SLOW, especially remotely. I suggest you make a rsync copy of the repository first, it will greatly speed up the import :
rsync -avHSP freeglut.svn.sourceforge.net::svn/freeglut/ freeglut.svn/
Then start the import with git-svn :
git svn clone --trunk=trunk/freeglut/freeglut file://$(pwd)/freeglut.svn/ freeglut-git/
And edit .git/config to point to https://freeglut.svn.sourceforge.net/svnroot/freeglut :
[svn-remote "svn"]
url = https://freeglut.svn.sourceforge.net/svnroot/freeglut
fetch = trunk/freeglut/freeglut:refs/remotes/trunk
I work with 2 branches:
- master : the SVN on-going sync - may be rebased to push with
git svn dcommit - android : my feature branch - not rebased and hence trackable by contributors
Here's how I synchronize the upstream repository and merge it regularly with my feature branch:
git svn fetch
git checkout master
git merge remotes/trunk
git checkout android # my feature branch
git merge master
# if conflict
git add .../sthing.c
git commit -m "Merge master"
git push
Any better way?
The ongoing work is available at https://gitorious.org/freeglut/android
If you ever get this cryptic error when loading an Android native app:
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{org.wikibooks.OpenGL/android.app.NativeActivity}: java.lang.IllegalArgumentException: Unable to load native library: /data/data/org.wikibooks.OpenGL/lib/libnative-activity.so
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784)
at android.app.ActivityThread.access$1500(ActivityThread.java:123)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3835)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: Unable to load native library: /data/data/org.wikibooks.OpenGL/lib/libnative-activity.so
at android.app.NativeActivity.onCreate(NativeActivity.java:199)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1722)
... 11 more
This may mean that Java couldn't find the ANativeActivity_onCreate function in your code, because it was stripped by the compiler.
If you use the native_app_glue NDK module, you may have noticed this strange code:
// Make sure glue isn't stripped. app_dummy();
Let's experiment what happens with and without this line:
Calling app_dummy:
$ arm-linux-androideabi-objdump -T libs/armeabi/libnative-activity.so | grep ANativeActivity_onCreate
000067fc g DF .text 000000f8 ANativeActivity_onCreate
Not calling app_dummy :
$ arm-linux-androideabi-objdump -T libs/armeabi/libnative-activity.so | grep ANativeActivity_onCreate
$ # nothing
native_app_glue mainly defines Android callbacks. Since none of them are called directly by your code, the compiler strips the android_native_app_glue.o module entirely. If you use app_dummy however, it embeds it. Fortunately the compiler cannot strip the module on a per-function basis
That's why you need to call app_dummy when using the native_app_glue NDK module.
This looks like a ugly work-around though - isn't there a cleaner way?
If you want to use FreeType in your native C/C++ Android app, you'll need to cross-compile it. The Android system uses FreeType internally but it doesn't expose it to native apps.
First, prepare the cross-compiler from the NDK:
/usr/src/android-ndk-r7/build/tools/make-standalone-toolchain.sh \ --platform=android-9 \ --install-dir=/usr/src/ndk-standalone-9 PATH=/usr/src/ndk-standalone-9/bin:$PATH
Then use it to cross-compile freetype:
tar xf freetype-2.4.8.tar.bz2 cd freetype-2.4.8/ CFLAGS="-std=gnu99" ./configure --host=arm-linux-androideabi --prefix=/freetype \ --without-zlib make make install DESTDIR=$(pwd)
See this discussion for the --std option.
--without-zlib uses the internal copy of zlib inside freetype rather than one independently recompiled for Android. Otherwise you'd get errors such as:
./obj/local/armeabi/libfreetype.a(ftgzip.o): In function `ft_gzip_file_init':
ftgzip.c:(.text+0x3c4): undefined reference to `inflateInit2_'
./obj/local/armeabi/libfreetype.a(ftgzip.o): In function `ft_gzip_file_done':
ftgzip.c:(.text+0x43c): undefined reference to `inflateEnd'
./obj/local/armeabi/libfreetype.a(ftgzip.o): In function `ft_gzip_file_reset':
ftgzip.c:(.text+0x514): undefined reference to `inflateReset'
./obj/local/armeabi/libfreetype.a(ftgzip.o): In function `ft_gzip_file_fill_output':
ftgzip.c:(.text+0x780): undefined reference to `inflate'
Then write an Android.mk file in the new freetype/ directory:
##### LOCAL_PATH:= $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE := freetype LOCAL_SRC_FILES := lib/libfreetype.a LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include $(LOCAL_PATH)/include/freetype2 include $(PREBUILT_STATIC_LIBRARY) #####
See docs/STANDALONE-TOOLCHAIN.html and docs/PREBUILTS.html in the NDK for details. The CLEAR_VARS bit is not documented, but is necessary to avoid mixed-up paths; it is used in the native_app_glue NDK module.
To use FreeType in your project, edit your Android.mk:
... LOCAL_STATIC_LIBRARIES := ... freetype ... $(call import-module,freetype)
You will need to specify the freetype directory location as well, using the NDK_MODULE_PATH variable.
For instance, you can copy freetype in your project directory and build using:
ndk-build NDK_MODULE_PATH=. ...
[Latest version of these instructions can be found at the OpenGL Wikibook]
I got myself a second-hand Samsung Galaxy S at last, and started hacking on it!
The very first thing I wanted to try was porting the OpenGL wikibook C++ samples, that we wrote with OpenGL ES 2 in mind.
I started writing a minimal GLUT-compatible wrapper to run the samples as-is, using the Android NDK, and I'm making progress :) The Android NDK is getting nicer with Android 2.3, though it still feels less supported than Java apps (e.g. the resize events seem buggy and the keycodes header is incomplete...). Nonetheless, it's nice to be able to write C++ portable apps.
You can see how to use the wrapper, and how it works internally, at:
http://en.wikibooks.org/wiki/OpenGL_Programming/Installation/Android
One of the limitations is that GLES2 is not a true subset of OpenGL 2.1, in particular:
- the shader version is declared differently (#version 100 vs. #version 120)
- GLES2 shaders require float precision hints, but OpenGL 2.1 doesn't support them at all
I needed to pre-process these differences away, checking on GL_ES_VERSION_2_0 in the C++ source code to define a GLES2 macro in the shaders:
#ifdef GLES2 varying lowp vec4 f_color; # else varying vec4 f_color; #endif
Is there a better way?
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