ds-hwang / gbm_es2_demo

Example OpenGL ES2 demo using GBM and DRM(KMS) modesetting

GBM ES2 Demo

• Example OpenGL ES2 demo using GBM and DRM (KMS) modesetting
• This shows how ChromeOS renders GLES2 contents on the screen.
• It uses OpenGL ES2/3 without X11 dependency, so it fits pretty good with the embedded devices world.

Build

• If you are on Ubuntu, first make sure you have the dependencies installed

> sudo apt-get install libgles2-mesa-dev libgbm-dev

> mkdir build; cd build
> cmake ../
> make

Run

• I have successfully ran it on Ubuntu, ChromeOS and Yocto.

Ubuntu

• Go to tty1 with Ctrl + Alt + F1
• Kill gdm or lightdm because they are DRM master now. This demo has to be DRM master.

> sudo service lightdm stop

• Run the demo

> gbm_es2_demo
or
> gbm_es2_demo -M # mmap test

Yocto

• The easiest way to build embedded linux image is to use Yocto.
• I make Yocto recipes to make standalone emebeded OpenGL ES2 demo image.
• Check Yocto GBM ES2 Demo
• Enjoy building Linux image from the scratch.

Demo detail

gbm_es2_demo

• Show how to glue DRM, GBM and EGL
• Show how to swap buffer and vsync
• Show how to implement GLES2 app

gbm_es2_demo -M

• Same to gbm_es2_demo except for updating cube surface using dma_buf mmap
• It's very nice demo to show how Chromium zero-copy texture upload works. Chromium doesn't use glTexImage2D to update texture thank to new dma_buf mmap API. For more Chromium detail, check the chrome issue
• After Linux kernel v4.6, you can use following code. (currently only Intel Architecture supports it)
• Tiago Vignatti made this change in kernel.

  void* data = mmap(dma_buf_fd)
  update contents on |data|
  munmap(data)

Code style

• The style complying with Chromium’s style guide
• Before submitting a patch, always run clang-format

> clang-format-5.0 -i `find . -name "*.cpp" -o -name "*.h"`

Reference

• overview by jbarnes
• My mesa-demo
• My ChromeOS dma-test demo
• greatest drm tutorial by dvdhrm
• kmscube by robclark

gbm_es2_demo's Issues

error: 'GBM_BO_USE_LINEAR' was not declared in this scope

Any idea how to fix?

 # cmake ../
-- The C compiler identification is GNU 7.3.0
-- The CXX compiler identification is GNU 7.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29")
-- Checking for module 'libdrm'
--   Found libdrm, version 2.4.74
-- Checking for module 'gbm'
--   Found gbm, version 10.4.0
-- Checking for module 'egl'
--   Found egl, version 7.10
-- Checking for module 'glesv2'
--   Found glesv2, version
ged links drmgbmEGLGLESv2
gbm_es2_demo links ged
dma_buf_mmap_demo links ged
-- Configuring done
-- Generating done
-- Build files have been written to: /mnt/src/gbm_es2_demo/build
armhf ch root /mnt/src/gbm_es2_demo/build > # make
Scanning dependencies of target ged
[ 12%] Building CXX object ged_lib/CMakeFiles/ged.dir/drm_modesetter.cpp.o
[ 25%] Building CXX object ged_lib/CMakeFiles/ged.dir/egl_drm_glue.cpp.o
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp: In member function 'bool ged::{anonymous}::StreamTextureImpl::Initialize(gbm_device*)':
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:147:46: error: 'GBM_BO_USE_LINEAR' was not declared in this scope
                         GBM_FORMAT_ARGB8888, GBM_BO_USE_LINEAR);
                                              ^~~~~~~~~~~~~~~~~
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:147:46: note: suggested alternative: 'GBM_BO_USE_WRITE'
                         GBM_FORMAT_ARGB8888, GBM_BO_USE_LINEAR);
                                              ^~~~~~~~~~~~~~~~~
                                              GBM_BO_USE_WRITE
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:164:50: warning: narrowing conversion of '((ged::{anonymous}::StreamTextureImpl*)this)->ged::{anonymous}::StreamTextureImpl::dimension_.ged::StreamTexture::Dimension::width' from 'size_t {aka unsigned int}' to 'EGLint {aka int}' inside { } [-Wnarrowing]
                                       dimension_.width,
                                       ~~~~~~~~~~~^~~~~
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:166:50: warning: narrowing conversion of '((ged::{anonymous}::StreamTextureImpl*)this)->ged::{anonymous}::StreamTextureImpl::dimension_.ged::StreamTexture::Dimension::height' from 'size_t {aka unsigned int}' to 'EGLint {aka int}' inside { } [-Wnarrowing]
                                       dimension_.height,
                                       ~~~~~~~~~~~^~~~~~
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:170:50: warning: narrowing conversion of '((ged::{anonymous}::StreamTextureImpl*)this)->ged::{anonymous}::StreamTextureImpl::dimension_.ged::StreamTexture::Dimension::stride' from 'size_t {aka unsigned int}' to 'EGLint {aka int}' inside { } [-Wnarrowing]
                                       dimension_.stride,
                                       ~~~~~~~~~~~^~~~~~
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp: In member function 'bool ged::EGLDRMGlue::Impl::CreateFramebuffer(size_t, size_t, ged::EGLDRMGlue::Impl::Framebuffer&)':
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:478:47: warning: narrowing conversion of 'width' from 'size_t {aka unsigned int}' to 'EGLint {aka int ' inside { } [-Wnarrowing]
                                       EGL_NONE};
                                               ^
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:478:47: warning: narrowing conversion of 'height' from 'size_t {aka unsigned int}' to 'EGLint {aka int}' inside { } [-Wnarrowing]
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:478:47: warning: narrowing conversion of 'stride' from 'uint32_t {aka unsigned int}' to 'EGLint {aka int}' inside { } [-Wnarrowing]
/mnt/src/gbm_es2_demo/ged_lib/egl_drm_glue.cpp:478:47: warning: narrowing conversion of 'offset' from 'uint32_t {aka unsigned int}' to 'EGLint {aka int}' inside { } [-Wnarrowing]
ged_lib/CMakeFiles/ged.dir/build.make:75: recipe for target 'ged_lib/CMakeFiles/ged.dir/egl_drm_glue.cpp.o' failed
make[2]: *** [ged_lib/CMakeFiles/ged.dir/egl_drm_glue.cpp.o] Error 1
CMakeFiles/Makefile2:85: recipe for target 'ged_lib/CMakeFiles/ged.dir/all' failed
make[1]: *** [ged_lib/CMakeFiles/ged.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2

Segmentation fault on Ubuntu16.04

The demo was failing with segmentation fault on ubuntu16.04 because of this line:
egl_.display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
If it is changed to
egl_.display = eglGetDisplay((EGLNativeDisplayType)gbm_);
is working.

Why it works only when chrom running?

It write "failed to initialize
failed to initialize EGL
" when it is not running. In joone C demo.
In this demo it write "using card: '/dev/card0': Success
" and it show nothing. Rust demo works fine.