Backends: OpenGL3: Add glad 2 to OpenGL loaders. (#3330)

examples/example_glfw_opengl3/Makefile

@@ -42,6 +42,10 @@ CXXFLAGS += -I../libs/gl3w -DIMGUI_IMPL_OPENGL_LOADER_GL3W
 # SOURCES += ../libs/glad/src/glad.c
 # CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD
 
+## Using OpenGL loader: glad2
+# SOURCES += ../libs/glad/src/gl.c
+# CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD2
+
 ## Using OpenGL loader: glbinding
 ## This assumes a system-wide installation
 ## of either version 3.0.0 (or newer)

examples/example_glfw_opengl3/main.cpp

@@ -17,6 +17,8 @@
 #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_GLAD2)
+#include <glad/gl.h>            // Initialize with gladLoadGL(...) or gladLoaderLoadGL()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
 #define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
 #include <glbinding/Binding.h>  // Initialize with glbinding::Binding::initialize()
@@ -84,6 +86,8 @@ 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_GLAD2)
+    bool err = gladLoadGL(glfwGetProcAddress) == 0; // glad docs recommend using the windowing library loader instead of the (optionally) bundled one.
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
     bool err = false;
     glbinding::Binding::initialize();

examples/example_sdl_opengl3/Makefile

@@ -42,6 +42,10 @@ CXXFLAGS += -I../libs/gl3w -DIMGUI_IMPL_OPENGL_LOADER_GL3W
 # SOURCES += ../libs/glad/src/glad.c
 # CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD
 
+## Using OpenGL loader: glad2
+# SOURCES += ../libs/glad/src/gl.c
+# CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD2
+
 ## Using OpenGL loader: glbinding
 ## This assumes a system-wide installation
 ## of either version 3.0.0 (or newer)

examples/example_sdl_opengl3/main.cpp

@@ -19,6 +19,8 @@
 #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_GLAD2)
+#include <glad/gl.h>            // Initialize with gladLoadGL(...) or gladLoaderLoadGL()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
 #define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
 #include <glbinding/Binding.h>  // Initialize with glbinding::Binding::initialize()
@@ -79,6 +81,8 @@ 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_GLAD2)
+    bool err = gladLoadGL((GLADloadfunc) SDL_GL_GetProcAddress) == 0; // glad docs recommend using the windowing library loader instead of the (optionally) bundled one.
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
     bool err = false;
     glbinding::Binding::initialize();

examples/imgui_impl_opengl3.cpp

@@ -13,6 +13,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2020-07-01: OpenGL: Added support for glad2 OpenGL loader.
 //  2020-05-08: OpenGL: Made default GLSL version 150 (instead of 130) on OSX.
 //  2020-04-21: OpenGL: Fixed handling of glClipControl(GL_UPPER_LEFT) by inverting projection matrix.
 //  2020-04-12: OpenGL: Fixed context version check mistakenly testing for 4.0+ instead of 3.2+ to enable ImGuiBackendFlags_RendererHasVtxOffset.
@@ -101,6 +102,8 @@
 #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_GLAD2)
+#include <glad/gl.h>            // Needs to be initialized with gladLoadGL(...) or gladLoaderLoadGL() in user's code.
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
 #ifndef GLFW_INCLUDE_NONE
 #define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
@@ -189,6 +192,8 @@ 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_GLAD2)
+    gl_loader = "GLAD2";
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
     gl_loader = "glbinding2";
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)

examples/imgui_impl_opengl3.h

@@ -49,6 +49,7 @@ IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GL3W) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLEW) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLAD) \
+ && !defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
@@ -68,6 +69,8 @@ IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();
     #define IMGUI_IMPL_OPENGL_LOADER_GLEW
 #elif __has_include(<glad/glad.h>)
     #define IMGUI_IMPL_OPENGL_LOADER_GLAD
+#elif __has_include(<glad/gl.h>)
+    #define IMGUI_IMPL_OPENGL_LOADER_GLAD2
 #elif __has_include(<GL/gl3w.h>)
     #define IMGUI_IMPL_OPENGL_LOADER_GL3W
 #elif __has_include(<glbinding/glbinding.h>)