OpenGL backend (stage 1) (#535)

* [skip ci] basic start up for opengl

[skip ci] test inout data[3] success

[skip ci] try to pass kernel arguments

* [skip ci] use a struct_metal style struct compiler

* [skip ci] basic allocator

* [skip ci] basic read/write tensor

fix bug x[4] -> x[4 >> 2] = x[1]

* adding f32&f64 support for opengl

remove opengl from all_archs to prevent test

* Update test_abs.py

* Update TaichiCore.cmake for TI_WITH_OPENGL

optional TI_WITH_OPENGL ON (detect auto OFF)

TI_WITH_OPENGL guard opengl_api.cpp

fix typo

* merge g1 with master fix: x86_64 -> x64

Update profiler.cpp

* replace opengl_unary_op_type_symbol with unary_op_type_name

* snode_io_arch -> snode_accessor_arch

* use GLEW_LIBRARY_DIR

TI_WITH_OPENGL=OFF by default

TI_WITH_OPENGL default to ON

* no more USE_GLEW macro

* no more mallocs in SSBO

* remove opengl_backend.py, add comment in mpm99 for ti.opengl

* fix memory leakage using std::vector

* better cmake: find GLFW and glfw3

* support arch: uncomment with_opengl

* initialize_opengl in materialize_layout

fix typo

Co-authored-by: Yuanming Hu <[email protected]>

cmake/TaichiCore.cmake

@@ -24,6 +24,8 @@ endif()
 
 option(USE_STDCPP "Use -stdlib=libc++" OFF)
 option(TI_WITH_CUDA "Build with CUDA support" OFF)
+option(TI_WITH_OPENGL "Build with OpenGL backend" ON)
+option(GLEW_USE_STATIC_LIBS OFF)
 
 include_directories(${CMAKE_SOURCE_DIR})
 include_directories(external/xxhash)
@@ -53,6 +55,29 @@ if (TI_WITH_CUDA)
     endif()
 endif()
 
+if (TI_WITH_OPENGL)
+  if(NOT GLEW_VERSION)
+    set(GLEW_VERSION 2.0.0)
+  endif()
+  find_package(GLEW ${GLEW_VERSION})
+  if (GLEW_FOUND)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DTI_WITH_OPENGL")
+    message("Building with GLEW ${GLEW_VERSION}")
+    message("Using GLEW: ${GLEW_LIBRARIES}")
+    target_include_directories(${LIBRARY_NAME} PUBLIC ${GLEW_INCLUDE_DIRS})
+    target_link_libraries(${LIBRARY_NAME} ${GLEW_LIBRARIES} GLEW)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DGLEW_STATIC")
+    find_package(glfw3 REQUIRED)
+    if (NOT glfw3_FOUND)
+      message(FATAL_ERROR "glfw3 not found.")
+    endif()
+    message("Building with glfw ${glfw3_VERSION}")
+    target_link_libraries(${LIBRARY_NAME} glfw)
+  else()
+    message(WARNING "GLEW not found, ignoring TI_WITH_OPENGL.")
+  endif()
+endif()
+
 # http://llvm.org/docs/CMake.html#embedding-llvm-in-your-project
 find_package(LLVM REQUIRED CONFIG 8.0)
 message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")

examples/mpm99.py

@@ -1,5 +1,5 @@
 import taichi as ti
-ti.init(arch=ti.cuda) # Try to run on GPU
+ti.init(arch=ti.cuda) # Try to run on GPU. Use arch=ti.opengl on old GPUs
 quality = 1 # Use a larger value for higher-res simulations
 n_particles, n_grid = 9000 * quality ** 2, 128 * quality
 dx, inv_dx = 1 / n_grid, float(n_grid)

python/taichi/lang/__init__.py

@@ -29,6 +29,7 @@
 x64 = core.x64
 cuda = core.cuda
 metal = core.metal
+opengl = core.opengl
 profiler_print = lambda: core.get_current_program().profiler_print()
 profiler_clear = lambda: core.get_current_program().profiler_clear()
 profiler_start = lambda n: core.get_current_program().profiler_start(n)
@@ -222,6 +223,8 @@ def supported_archs():
     archs.append(cuda)
   if ti.core.with_metal():
     archs.append(metal)
+  if ti.core.with_opengl():
+    archs.append(opengl)
   return archs
 
 class _ArchCheckers(object):