Making enjalot script on OpenCL-OpenGL interoperability

notes_on_starting_with_opencl-opengl-interoperability.md

The code: https://github.com/enjalot/adventures_in_opencl/tree/master/part2/

From the README:

We demonstrate OpenCL and OpenGL context sharing by making a simple particle system.

Build: make a build directory and build the tutorial

 mkdir build
 cd build
 cmake ..
 make

execute the example program

 ./part2.x

On cmake .. had:

CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
...
GLEW_INCLUDE_PATH
...
GLEW_LIBRARY

According to ubuntuforum from 2009 changed GLEW_LIBRARY to GLEW_LIBRARIES in the CMakeLists.txt. The plural ending of the variable was present at all the rest of GET_... variables in TARGET_LINK_LIBRARIES. Similar irregularity was present in GLEW_INCLUDE_PATH -- the rest of INCLUDE_DIRECTORIES had ..._DIR instead of ...PATH on the end. Corrected that. cmake .. worked fine.

make reported missing fatal error: GL/glew.h: No such file or directory. Found them (apt-file search GL/glew.h) in libglew-dev. Installed it. Now make has lots of undefined reference to __glewBindBuffer and alike.

Looking at title "Could NOT find GLEW (missing: GLEW_INCLUDE_DIR GLEW_LIBRARY)" of the issue, and getting that headers were found, but the function definitions were not, changed GLEW_LIBRARIES back to GLEW_LIBRARY in CMakeLists.txt.

Compiled!

Some window pops and disapears.
o_O how is it supposed to run?
Adding a getchar() at the end of main does not stop anything.

The crash point:

cl_vbos.push_back(cl::BufferGL(context, CL_MEM_READ_WRITE, p_vbo, &err));

btw without root everything breaks with fish: Job 1, “./part2.x ” terminated by signal SIGSEGV (Address boundary error)

#define NUM_PARTICLES 2 instead of 20000 does not help.

Put printf("p_vbo = %d", p_vbo); before cl_vbos.push_back(... p_vbo,...); -- the print breaks. p_vbo is not set.

Now the print works for some reason.
But cl_vbos.push_back( cl::BufferGL(context, CL_MEM_READ_WRITE, p_vbo, &err)); does not.
std::vector<cl::Memory> cl_vbos;

Yap

>>> gpu
<pyopencl.Device 'Intel(R) HD Graphics IvyBridge M GT2' on 'Intel Gen OCL Driver' at 0x7ff612fefdc0>
>>> gpu.extensions
'cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_byte_addressable_store cl_khr_icd'
>>> 'sharing' in gpu.extensions
False

no cl_khr_gl_sharing on HD4000

But!

>>> amd_cpu
<pyopencl.Device 'Intel(R) Core(TM) i5-3317U CPU @ 1.70GHz' on 'AMD Accelerated Parallel Processing' at 0x1689bd0>
>>> amd_cpu.extensions
'cl_khr_fp64 cl_amd_fp64 cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_int64_base_atomics cl_khr_int64_extended_atomics cl_khr_3d_image_writes cl_khr_byte_addressable_store cl_khr_gl_sharing cl_ext_device_fission cl_amd_device_attribute_query cl_amd_vec3 cl_amd_printf cl_amd_media_ops cl_amd_media_ops2 cl_amd_popcnt '
>>> 'cl_khr_gl_sharing' in amd_cpu.extensions
True

(clinfo btw)

Ok, now the it runs.

$ ./part2.x 
Hello, OpenCL
Initialize OpenCL object and context
cl::Platform::get(): CL_SUCCESS
platforms.size(): 3
getDevices: CL_SUCCESS
devices.size(): 1
type: device: 2 CL_DEVICE_TYPE_CPU: 2 
(X) Before defining OS-specific context properties.
(X) Defining OS-specific context properties after Win32 if branch (final else, must be Linux?).
(X) Create command queue.
load the program
kernel size: 408
build program
done building program
Build Status: 0
Build Options:  
Build Log:   
Creating VBO
created VBO, activated, uploaded the data
checked the data is the same as in the input
bound buffer, id = 1
Creating VBO
created VBO, activated, uploaded the data
checked the data is the same as in the input
bound buffer, id = 2
gl interop!
LKAJFA
p_vbo = 1
c_vbo = 2
aaaaaaaaaaaaaa
created OpenCL buffer from GL VBO 1
created OpenCL buffer from GL VBO 2
create OpenCL only arrays
Pushing data to the GPU
push our CPU arrays to the CPU
in popCorn

But no particles in the window.
Does OpenGL run on CPU now?