Support older 2.x series of glbinding as loader for OpenGL3

For the moment I have only the older 2.x series available on my system
which uses slightly different header filenames and initialisation, so
as a slight variation of the 3.x series support recently implemented
here the glue needed to make 2.x series work as well.

As having a versioned and a unversioned definition is deemed to
confusing we use the unversioned definition for auto-detection on
supporting compilers and add two versioned definitions for explicit
requests.

References: ocornut#2870, 5e2329b

examples/example_glfw_opengl3/Makefile

@@ -44,6 +44,10 @@ CXXFLAGS += -I../libs/gl3w -DIMGUI_IMPL_OPENGL_LOADER_GL3W
 ## Using OpenGL loader: glbinding
 ## (This assumes a system-wide installation)
 # CXXFLAGS += -lglbinding -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING
+## If autodetection fails for some reason you can select one of
+## the supported versions explicitly with:
+# CXXFLAGS += -lglbinding -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING_2
+# CXXFLAGS += -lglbinding -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING_3
 
 ##---------------------------------------------------------------------
 ## BUILD FLAGS PER PLATFORM

examples/example_glfw_opengl3/main.cpp

@@ -17,9 +17,13 @@
 #include <GL/glew.h>    // Initialize with glewInit()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
 #include <glad/glad.h>  // Initialize with gladLoadGL()
-#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING)
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2) || defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3)
 #define GLFW_INCLUDE_NONE         // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
+#if defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2)
+#include <glbinding/Binding.h>    // Initialize with glbinding::Binding::initialize()
+#else
 #include <glbinding/glbinding.h>  // Initialize with glbinding::initialize()
+#endif
 #include <glbinding/gl/gl.h>
 using namespace gl;
 #else
@@ -79,7 +83,10 @@ int main(int, char**)
     bool err = glewInit() != GLEW_OK;
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
     bool err = gladLoadGL() == 0;
-#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING)
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2)
+    bool err = false;
+    glbinding::Binding::initialize();
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3)
     bool err = false;
     glbinding::initialize([](const char* name) { return (glbinding::ProcAddress)glfwGetProcAddress(name); });
 #else

examples/example_sdl_opengl3/Makefile

@@ -44,6 +44,10 @@ CXXFLAGS += -I../libs/gl3w -DIMGUI_IMPL_OPENGL_LOADER_GL3W
 ## Using OpenGL loader: glbinding
 ## (This assumes a system-wide installation)
 # CXXFLAGS += -lglbinding -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING
+## If autodetection fails for some reason you can select one of
+## the supported versions explicitly with:
+# CXXFLAGS += -lglbinding -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING_2
+# CXXFLAGS += -lglbinding -DIMGUI_IMPL_OPENGL_LOADER_GLBINDING_3
 
 ##---------------------------------------------------------------------
 ## BUILD FLAGS PER PLATFORM

examples/example_sdl_opengl3/main.cpp

@@ -19,8 +19,12 @@
 #include <GL/glew.h>    // Initialize with glewInit()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
 #include <glad/glad.h>  // Initialize with gladLoadGL()
-#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING)
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2) || defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3)
+#if defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2)
+#include <glbinding/Binding.h>    // Initialize with glbinding::Binding::initialize()
+#else
 #include <glbinding/glbinding.h>  // Initialize with glbinding::initialize()
+#endif
 #include <glbinding/gl/gl.h>
 using namespace gl;
 #else
@@ -73,9 +77,12 @@ int main(int, char**)
     bool err = glewInit() != GLEW_OK;
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
     bool err = gladLoadGL() == 0;
-#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING)
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2)
+    bool err = false;
+    glbinding::Binding::initialize();
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3)
     bool err = false;
-    glbinding::initialize([](const char* name) { return (glbinding::ProcAddress)SDL_GL_GetProcAddress(name); });
+    glbinding::initialize([](const char* name) { return (glbinding::ProcAddress)glfwGetProcAddress(name); });
 #else
     bool err = false; // If you use IMGUI_IMPL_OPENGL_LOADER_CUSTOM, your loader is likely to requires some form of initialization.
 #endif

examples/imgui_impl_opengl3.cpp

@@ -87,13 +87,17 @@
 #undef IMGUI_IMPL_OPENGL_LOADER_GLEW
 #undef IMGUI_IMPL_OPENGL_LOADER_GLAD
 #undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING
+#undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2
+#undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3
 #undef IMGUI_IMPL_OPENGL_LOADER_CUSTOM
 #elif defined(__EMSCRIPTEN__)
 #define IMGUI_IMPL_OPENGL_ES2           // Emscripten    -> GL ES 2, "#version 100"
 #undef IMGUI_IMPL_OPENGL_LOADER_GL3W
 #undef IMGUI_IMPL_OPENGL_LOADER_GLEW
 #undef IMGUI_IMPL_OPENGL_LOADER_GLAD
 #undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING
+#undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2
+#undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3
 #undef IMGUI_IMPL_OPENGL_LOADER_CUSTOM
 #endif
 #endif
@@ -118,9 +122,13 @@
 #include <GL/glew.h>    // Needs to be initialized with glewInit() in user's code
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
 #include <glad/glad.h>  // Needs to be initialized with gladLoadGL() in user's code
-#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING)
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2) || defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3)
 #include <glbinding/gl/gl.h>  // Initialize with glbinding::initialize()
+#if defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2)
+#include <glbinding/Binding.h>
+#else
 #include <glbinding/glbinding.h>
+#endif
 using namespace gl;
 #else
 #include IMGUI_IMPL_OPENGL_LOADER_CUSTOM
@@ -193,8 +201,10 @@ bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
     gl_loader = "GLEW";
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
     gl_loader = "GLAD";
-#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING)
-    gl_loader = "glbinding";
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2)
+    gl_loader = "glbinding2";
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3)
+    gl_loader = "glbinding3";
 #else // IMGUI_IMPL_OPENGL_LOADER_CUSTOM
     gl_loader = "Custom";
 #endif

examples/imgui_impl_opengl3.h

@@ -43,10 +43,26 @@ IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();
 // If auto-detection fails or doesn't select the same GL loader file as used by your application,
 // you are likely to get a crash in ImGui_ImplOpenGL3_Init().
 // You can explicitly select a loader by using '#define IMGUI_IMPL_OPENGL_LOADER_XXX' in imconfig.h or compiler command-line.
+#if defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING)
+    #if defined(__has_include)
+        #if __has_include(<glbinding/glbinding.h>)
+            #define IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3
+            #undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING
+        #elif __has_include(<glbinding/Binding.h>)
+            #define IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2
+            #undef IMGUI_IMPL_OPENGL_LOADER_GLBINDING
+        #else
+            #error "Cannot auto-detect GLBinding version as expected headers are not present!"
+        #endif
+    #else
+        #error "Cannot auto-detect GLBinding version as your compiler does not provide a method of header detection!"
+    #endif
+#endif
 #if !defined(IMGUI_IMPL_OPENGL_LOADER_GL3W) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLEW) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLAD) \
- && !defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING) \
+ && !defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2) \
+ && !defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
     #if defined(__has_include)
         #if __has_include(<GL/glew.h>)
@@ -55,8 +71,10 @@ IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();
             #define IMGUI_IMPL_OPENGL_LOADER_GLAD
         #elif __has_include(<GL/gl3w.h>)
             #define IMGUI_IMPL_OPENGL_LOADER_GL3W
-        #elif __has_include(<glbinding/gl/gl.h>)
-            #define IMGUI_IMPL_OPENGL_LOADER_GLBINDING
+        #elif __has_include(<glbinding/glbinding.h>)
+            #define IMGUI_IMPL_OPENGL_LOADER_GLBINDING_3
+        #elif __has_include(<glbinding/Binding.h>)
+            #define IMGUI_IMPL_OPENGL_LOADER_GLBINDING_2
         #else
             #error "Cannot detect OpenGL loader!"
         #endif