Removed support for using GLEW

Use of GLEW has been deprecated since v3.4.3 (April 2020) when OpenSubdiv
was updated to use an internal namespace protected GL loader.

Client code is of course free to continue using GLEW or any other GL loader,

WIP PixarAnimationStudios#913 internal issue #OSD-139

CMakeLists.txt

@@ -313,7 +313,6 @@ add_definitions(${OSD_COMPILER_FLAGS})
 set(CMAKE_SUPPRESS_REGENERATION TRUE)
 
 option(PTEX_LOCATION "Path to Ptex" "")
-option(GLEW_LOCATION "Path to GLEW" "")
 option(GLFW_LOCATION "Path to GLFW" "")
 
 option(NO_LIB "Disable the opensubdiv libs build (caveat emptor)" OFF)
@@ -332,7 +331,6 @@ option(NO_METAL "Disable Metal support" OFF)
 option(NO_DX "Disable DirectX support")
 option(NO_TESTS "Disable all tests")
 option(NO_GLTESTS "Disable GL tests")
-option(NO_GLEW "Disable use of GLEW" ON)
 option(NO_GLFW "Disable components depending on GLFW" OFF)
 option(NO_GLFW_X11 "Disable GLFW components depending on X11" OFF)
 option(NO_MACOS_FRAMEWORK "Disable generation of framework on macOS" OFF)
@@ -386,18 +384,7 @@ if (OPENGL_FOUND AND NOT IOS)
     add_definitions(
         -DOPENSUBDIV_HAS_OPENGL
     )
-    if (NOT NO_GLEW)
-        if (APPLE)
-            find_package(GLEW)
-        else()
-            find_package(GLEW REQUIRED)
-        endif()
-    endif()
-    if(GLEW_FOUND)
-        add_definitions( -DOSD_USES_GLEW )
-    else()
-        add_definitions( -DOSD_USES_INTERNAL_GLAPILOADER )
-    endif()
+    add_definitions( -DOSD_USES_INTERNAL_GLAPILOADER )
 endif()
 
 if (WIN32 AND NOT NO_DX)
@@ -484,18 +471,7 @@ macro(osd_detect_gl_version header)
 
 endmacro()
 
-if(GLEW_FOUND AND GLEW_INCLUDE_DIR)
-
-    osd_detect_gl_version(${GLEW_INCLUDE_DIR}/GL/glew.h)
-    set(OPENGL_LOADER_INCLUDE_DIRS
-        ${GLEW_INCLUDE_DIR}
-        ${PROJECT_SOURCE_DIR}/glLoader)
-    set(OPENGL_LOADER_LIBRARIES
-        ${GLEW_LIBRARY}
-        OpenGL::GL
-        ${CMAKE_DL_LIBS})
-
-elseif(OPENGL_FOUND)
+if(OPENGL_FOUND)
 
     osd_detect_gl_version(${PROJECT_SOURCE_DIR}/glLoader/glApi.h)
     set(OPENGL_LOADER_INCLUDE_DIRS
@@ -657,13 +633,6 @@ else()
 endif()
 
 if (WIN32)
-    if ("${GLEW_LIBRARY}" MATCHES "glew32s(d|)")
-        # Link against the static version of GLEW
-        add_definitions(
-            -DGLEW_STATIC
-        )
-    endif()
-
     if (DXSDK_FOUND AND NOT NO_DX)
         add_definitions(
             -DOPENSUBDIV_HAS_DX11SDK

glLoader/glLoader.cpp

@@ -36,41 +36,14 @@ namespace GLLoader {
 bool
 applicationInitializeGL()
 {
-#if defined(OSD_USES_INTERNAL_GLAPILOADER)
     // -- GLAPILOADER
     return OpenSubdiv::internal::GLApi::glApiLoad();
-
-#elif defined(OSD_USES_GLEW)
-    // -- GLEW
-#define CORE_PROFILE
-#ifdef CORE_PROFILE
-    // this is the only way to initialize GLEW (before GLEW 1.13)
-    // correctly under core profile context.
-    glewExperimental = true;
-#endif
-    GLenum status = glewInit();
-    if (status != GLEW_OK) {
-        printf("Failed to initialize glew. Error = %s\n",
-               glewGetErrorString(status));
-        return false;
-    }
-#ifdef CORE_PROFILE
-    // clear GL errors which were generated during glewInit()
-    glGetError();
-#endif
-#endif
-    return true;
 }
 
 bool
 libraryInitializeGL()
 {
-#if defined(OSD_USES_INTERNAL_GLAPILOADER)
     return OpenSubdiv::internal::GLApi::glApiLoad();
-#else
-    // otherwise do nothing
-    return true;
-#endif
 }
 
 

glLoader/glLoader.h

@@ -142,13 +142,6 @@
     #include "glApi.h"
 
     #define OSD_OPENGL_HAS(token) (GLAPILOADER_GL_##token)
-
-#elif defined(OSD_USES_GLEW)
-    // -- GLEW
-    #include <GL/glew.h>
-
-    #define OSD_OPENGL_HAS(token) (GLEW_##token)
-
 #endif
 
 namespace OpenSubdiv {

opensubdiv/osd/opengl.h

@@ -30,11 +30,7 @@
     #if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR
         #include <OpenGLES/ES2/gl.h>
     #else
-        #if defined(OSD_USES_GLEW)
-            #include <GL/glew.h>
-        #else
-            #include <OpenGL/gl3.h>
-        #endif
+        #include <OpenGL/gl3.h>
     #endif
 #elif defined(ANDROID)
     #include <GLES2/gl2.h>
@@ -43,11 +39,7 @@
         #define WIN32_LEAN_AND_MEAN
         #include <windows.h>
     #endif
-    #if defined(OSD_USES_GLEW)
-        #include <GL/glew.h>
-    #else
-        #include <GL/gl.h>
-    #endif
+    #include <GL/gl.h>
 #endif
 
 #endif  // OPENSUBDIV3_OSD_OPENGL_H