Refactor the rendering context flags to not be a combo box.

This way in the future it is easier to make currently mutually exclusive
compile options be all enabled at the same time.

CMake/VTKmConfig.cmake.in

@@ -61,7 +61,9 @@ set(VTKm_BUILD_SHARED_LIBS "@BUILD_SHARED_LIBS@")
 set(VTKm_ENABLE_CUDA "@VTKm_ENABLE_CUDA@")
 set(VTKm_ENABLE_TBB "@VTKm_ENABLE_TBB@")
 set(VTKm_ENABLE_RENDERING "@VTKm_ENABLE_RENDERING@")
-set(VTKm_RENDERING_BACKEND "@VTKm_RENDERING_BACKEND@")
+set(VTKm_ENABLE_GL_CONTEXT "@VTKm_ENABLE_GL_CONTEXT")
+set(VTKm_ENABLE_OSMESA_CONTEXT "@VTKm_ENABLE_OSMESA_CONTEXT")
+set(VTKm_ENABLE_EGL_CONTEXT "@VTKm_ENABLE_EGL_CONTEXT")
 set(VTKm_ENABLE_MPI "@VTKm_ENABLE_MPI@")
 
 # Load the library exports, but only if not compiling VTK-m itself
@@ -79,7 +81,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${VTKm_CMAKE_MODULE_PATH})
 include(VTKmWrappers)
 
 if(VTKm_ENABLE_RENDERING)
-  include(VTKmRenderingBackends)
+  include(VTKmRenderingContexts)
 endif()
 
 check_required_components(vtkm)

CMake/VTKmRenderingContexts.cmake

@@ -85,11 +85,11 @@ function(vtkm_find_gl)
 endfunction()
 
 #-----------------------------------------------------------------------------
-if(TARGET vtkm_rendering_backend)
+if(TARGET vtkm_rendering_gl_context)
   return()
 endif()
 
-add_library(vtkm_rendering_backend INTERFACE)
+add_library(vtkm_rendering_gl_context INTERFACE)
 if(NOT VTKm_RENDERING_BACKEND STREQUAL "None")
   vtkm_find_gl(REQUIRED GL GLEW
                OPTIONAL
@@ -97,18 +97,18 @@ if(NOT VTKm_RENDERING_BACKEND STREQUAL "None")
 endif()
 
 #-----------------------------------------------------------------------------
-if(VTKm_RENDERING_BACKEND STREQUAL "OpenGL")
+if(VTKm_ENABLE_GL_CONTEXT)
   if(TARGET OpenGL::GLX)
-    target_link_libraries(vtkm_rendering_backend
+    target_link_libraries(vtkm_rendering_gl_context
                           INTERFACE OpenGL::OpenGL OpenGL::GLX GLEW::GLEW)
   elseif(TARGET OpenGL::GL)
-    target_link_libraries(vtkm_rendering_backend
+    target_link_libraries(vtkm_rendering_gl_context
                           INTERFACE OpenGL::GL GLEW::GLEW)
   endif()
-elseif(VTKm_RENDERING_BACKEND STREQUAL "OSMesa")
-  target_link_libraries(vtkm_rendering_backend
+elseif(VTKm_ENABLE_OSMESA_CONTEXT)
+  target_link_libraries(vtkm_rendering_gl_context
                         INTERFACE OpenGL::GL GLEW::GLEW)
-elseif(VTKm_RENDERING_BACKEND STREQUAL "EGL")
-  target_link_libraries(vtkm_rendering_backend
+elseif(VTKm_ENABLE_EGL_CONTEXT)
+  target_link_libraries(vtkm_rendering_gl_context
                         INTERFACE OpenGL::OpenGL OpenGL::EGL GLEW::GLEW)
 endif()

CMakeLists.txt

@@ -105,13 +105,9 @@ extract_version_components("${version_txt}" "VTKm")
 # Get the version from git if we can
 determine_version(${VTKm_SOURCE_DIR} ${GIT_EXECUTABLE} "VTKm")
 
-# Create an "interface" target library. This is not a real library but rather
-# holds CMake configuration that is required for CXX targets that use VTK-m
-# headers. In particular, it makes sure the appropriate C++11 version is being
-# used. (The cxx_constexpr and cxx_auto_type features happen to force C++11.
-# Directly asking for C++11 with this interface is not supported in CMake 3.3.)
-# This is also exported so that dependent CMake projects can load the same
-# configuration.
+# Create vtkm_compiler_flags library. This is an interface library that
+# holds all the C++ compiler flags that are needed for consumers and
+# when building VTK-m.
 include(VTKmCompilerFlags)
 include(VTKmWrappers)
 include(VTKmCPUVectorization)
@@ -245,7 +241,7 @@ install(
   FILES
     ${VTKm_SOURCE_DIR}/CMake/VTKmWrappers.cmake
     ${VTKm_SOURCE_DIR}/CMake/VTKmBackends.cmake
-    ${VTKm_SOURCE_DIR}/CMake/VTKmRenderingBackends.cmake
+    ${VTKm_SOURCE_DIR}/CMake/VTKmRenderingContexts.cmake
     ${VTKm_SOURCE_DIR}/CMake/VTKmExportHeaderTemplate.h.in
   DESTINATION ${VTKm_INSTALL_CMAKE_MODULE_DIR}
   )

examples/rendering/CMakeLists.txt

@@ -25,7 +25,7 @@ project(Rendering CXX)
 #Find the VTK-m package
 find_package(VTKm REQUIRED QUIET)
 
-if(NOT TARGET vtkm_rendering OR NOT VTKm_RENDERING_BACKEND STREQUAL "OpenGL")
+if(NOT TARGET vtkm_rendering OR NOT VTKm_ENABLE_GL_CONTEXT)
   return()
 endif()
 

vtkm/interop/testing/CMakeLists.txt

@@ -34,17 +34,17 @@ if(NOT TARGET GLUT::GLUT)
 endif()
 
 # rendering can only have a single backend so we need to
-if(VTKm_RENDERING_BACKEND STREQUAL "OSMesa" AND TARGET vtkm_rendering)
+if(VTKm_ENABLE_OSMESA_CONTEXT AND TARGET vtkm_rendering)
   list(APPEND unit_tests
     UnitTestTransferOSMesa.cxx
     UnitTestFancyTransferOSMesa.cxx
   )
-elseif(VTKm_RENDERING_BACKEND STREQUAL "EGL" AND TARGET vtkm_rendering)
+elseif(VTKm_ENABLE_EGL_CONTEXT AND TARGET vtkm_rendering)
   list(APPEND unit_tests
     UnitTestTransferEGL.cxx
     UnitTestFancyTransferEGL.cxx
   )
-elseif(VTKm_RENDERING_BACKEND STREQUAL "OpenGL" AND TARGET vtkm_rendering)
+elseif(VTKm_ENABLE_GL_CONTEXT AND TARGET vtkm_rendering)
   list(APPEND unit_tests
      UnitTestTransferGLUT.cxx
      UnitTestFancyTransferGLUT.cxx

vtkm/rendering/CMakeLists.txt

@@ -21,19 +21,23 @@
 if(NOT VTKm_ENABLE_RENDERING)
   return()
 endif()
-# determine what backend for rendering we want to build
 
-set(default_backend "None")
-if(NOT VTKm_RENDERING_BACKEND)
-  message(STATUS "Setting rendering backend to '${default_backend}' as none was specified.")
-  set(VTKm_RENDERING_BACKEND "${default_backend}" CACHE
-      STRING "Choose the backend for vtkm rendering." FORCE)
-  # Set the possible values of rendering backend types for cmake-gui
-  set(extra_backends )
-  if(UNIX AND NOT APPLE)
-    list(APPEND extra_backends "OSMesa" "EGL")
-  endif()
-  set_property(CACHE VTKm_RENDERING_BACKEND PROPERTY STRINGS "None" "OpenGL" ${extra_backends})
+# determine what context(s) for rendering we want to build
+option(VTKm_ENABLE_GL_CONTEXT "Enable GL context for vtkm rendering" OFF)
+if(UNIX AND NOT APPLE)
+  option(VTKm_ENABLE_OSMESA_CONTEXT "Enable OSMesa context for vtkm rendering" OFF)
+  option(VTKm_ENABLE_EGL_CONTEXT "Enable EGL context for vtkm rendering" OFF)
+  mark_as_advanced(VTKm_ENABLE_OSMESA_CONTEXT)
+  mark_as_advanced(VTKm_ENABLE_EGL_CONTEXT)
+endif()
+if(VTKm_ENABLE_GL_CONTEXT AND VTKm_ENABLE_OSMESA_CONTEXT)
+  message(FATAL_ERROR "VTK-m GL and OSMesa contexts are mutually exclusive")
+endif()
+if(VTKm_ENABLE_GL_CONTEXT AND VTKm_ENABLE_EGL_CONTEXT)
+  message(FATAL_ERROR "VTK-m GL and EGL contexts are mutually exclusive")
+endif()
+if(VTKm_ENABLE_EGL_CONTEXT AND VTKm_ENABLE_OSMESA_CONTEXT)
+  message(FATAL_ERROR "VTK-m EGL and OSMesa contexts are mutually exclusive")
 endif()
 
 set(headers
@@ -175,13 +179,13 @@ vtkm_library(
   WRAP_FOR_CUDA ${device_sources}
   )
 
-if(VTKm_RENDERING_BACKEND STREQUAL "OpenGL")
+if(VTKm_ENABLE_GL_CONTEXT)
   vtkm_declare_headers(${opengl_headers})
   target_sources(vtkm_rendering PRIVATE ${opengl_sources})
-elseif(VTKm_RENDERING_BACKEND STREQUAL "OSMesa")
+elseif(VTKm_ENABLE_OSMESA_CONTEXT)
   vtkm_declare_headers(${opengl_headers} ${osmesa_headers})
   target_sources(vtkm_rendering PRIVATE ${opengl_sources} ${osmesa_sources})
-elseif(VTKm_RENDERING_BACKEND STREQUAL "EGL")
+elseif(VTKm_ENABLE_EGL_CONTEXT)
   vtkm_declare_headers(${opengl_headers} ${egl_headers})
   target_sources(vtkm_rendering PRIVATE ${opengl_sources} ${egl_sources})
 endif()
@@ -194,9 +198,9 @@ if(UNIX AND NOT APPLE)
 endif()
 
 #-----------------------------------------------------------------------------
-include(VTKmRenderingBackends)
-target_link_libraries(vtkm_rendering PUBLIC vtkm_rendering_backend)
-  install(TARGETS vtkm_rendering_backend
+include(VTKmRenderingContexts)
+target_link_libraries(vtkm_rendering PUBLIC vtkm_rendering_gl_context)
+  install(TARGETS vtkm_rendering_gl_context
     EXPORT ${VTKm_EXPORT_NAME}
     )
 

vtkm/rendering/testing/CMakeLists.txt

@@ -35,13 +35,13 @@ set(unit_tests
 
 vtkm_unit_tests(SOURCES ${unit_tests} LIBRARIES vtkm_rendering)
 
-if(VTKm_RENDERING_BACKEND STREQUAL "OpenGL")
+if(VTKm_ENABLE_GL_CONTEXT)
   # message(STATUS "rendering testing/glfw needs a FindGLFW")
   # message(STATUS "rendering testing/glut needs compile corrections")
   # add_subdirectory(glfw)
   # add_subdirectory(glut)
-elseif(VTKm_RENDERING_BACKEND STREQUAL "OSMesa")
+elseif(VTKm_ENABLE_OSMESA_CONTEXT)
   add_subdirectory(osmesa)
-elseif(VTKm_RENDERING_BACKEND STREQUAL "EGL")
+elseif(VTKm_ENABLE_EGL_CONTEXT)
   add_subdirectory(egl)
 endif()