imgui_impl_opengl3: Advertised as a ES2/ES3 renderer. Defaults to ES3…

… on Android. Default on "#version 300 es" on ES 3. (#2002, #1873)

README.md

@@ -125,7 +125,7 @@ Languages: (third-party bindings)
 - Swift [swift-imgui](https://github.com/mnmly/Swift-imgui)
 
 Frameworks:
-- Renderers: DirectX 9, DirectX 10, DirectX 11, DirectX 12, Metal, OpenGL2, OpenGL3+, Vulkan: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
+- Renderers: DirectX 9, DirectX 10, DirectX 11, DirectX 12, Metal, OpenGL2, OpenGL3+/ES2/ES3, Vulkan: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
 - Platform: GLFW, SDL, Win32, OSX, Freeglut: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
 - Framework: Allegro 5, Marmalade: [examples/](https://github.com/ocornut/imgui/tree/master/examples)
 - Unmerged PR: SDL2 + OpenGLES + Emscripten: [#336](https://github.com/ocornut/imgui/pull/336)

examples/README.txt

@@ -111,7 +111,7 @@ List of Renderer Bindings in this repository:
     imgui_impl_dx12.cpp       ; DirectX12
     imgui_impl_metal.mm       ; Metal (with ObjC)
     imgui_impl_opengl2.cpp    ; OpenGL2 (legacy, fixed pipeline <- don't use with modern OpenGL context)
-    imgui_impl_opengl3.cpp    ; OpenGL3 (modern programmable pipeline)
+    imgui_impl_opengl3.cpp    ; OpenGL3, OpenGL ES 2, OpenGL ES 3 (modern programmable pipeline)
     imgui_impl_vulkan.cpp     ; Vulkan
 
 List of high-level Frameworks Bindings in this repository: (combine Platform + Renderer)
@@ -185,7 +185,7 @@ example_glfw_opengl2/
     = main.cpp + imgui_impl_glfw.cpp + imgui_impl_opengl2.cpp
 
 example_glfw_opengl3/
-    GLFW (Win32, Mac, Linux) + OpenGL3+ example (programmable pipeline, binding modern functions with GL3W).
+    GLFW (Win32, Mac, Linux) + OpenGL3+/ES2/ES3 example (programmable pipeline, binding modern functions with GL3W).
     This uses more modern OpenGL calls and custom shaders. 
     Prefer using that if you are using modern OpenGL in your application (anything with shaders).
     = main.cpp + imgui_impl_glfw.cpp + imgui_impl_opengl3.cpp
@@ -206,7 +206,7 @@ example_sdl_opengl2/
     = main.cpp + imgui_impl_sdl.cpp + imgui_impl_opengl2.cpp
 
 example_sdl_opengl3/
-    SDL2 (Win32, Mac, Linux, etc.) + OpenGL3+ example.
+    SDL2 (Win32, Mac, Linux, etc.) + OpenGL3+/ES2/ES3 example.
     This uses more modern OpenGL calls and custom shaders. 
     Prefer using that if you are using modern OpenGL in your application (anything with shaders).
     = main.cpp + imgui_impl_sdl.cpp + imgui_impl_opengl3.cpp

examples/imgui_impl_opengl3.cpp

@@ -1,4 +1,4 @@
-// ImGui Renderer for: OpenGL3 (modern OpenGL with shaders / programmatic pipeline)
+// ImGui Renderer for: OpenGL3 / OpenGL ES2 / OpenGL ES3 (modern OpenGL with shaders / programmatic pipeline)
 // This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)
 // (Note: We are using GL3W as a helper library to access OpenGL functions since there is no standard header to access modern OpenGL functions easily. Alternatives are GLEW, Glad, etc..)
 
@@ -11,6 +11,7 @@
 
 // CHANGELOG 
 // (minor and older changes stripped away, please see git history for details)
+//  2018-08-09: OpenGL: Default to OpenGL ES 3 on iOS and Android. GLSL version default to "#version 300 ES".
 //  2018-07-30: OpenGL: Support for GLSL 300 ES and 410 core. Fixes for Emscripten compilation.
 //  2018-07-10: OpenGL: Support for more GLSL versions (based on the GLSL version string). Added error output when shaders fail to compile/link.
 //  2018-06-08: Misc: Extracted imgui_impl_opengl3.cpp/.h away from the old combined GLFW/SDL+OpenGL3 examples.
@@ -61,13 +62,20 @@
 #include "TargetConditionals.h"
 #endif
 
-#if (defined(__APPLE__) && TARGET_OS_IOS) || (defined(__EMSCRIPTEN__))
+// iOS, Android and Emscripten can use GL ES 3
+// Call ImGui_ImplOpenGL3_Init() with "#version 300 es"
+#if (defined(__APPLE__) && TARGET_OS_IOS) || (defined(__ANDROID__)) || (defined(__EMSCRIPTEN__))
+#define USE_GL_ES3
+#endif
+
+#ifdef USE_GL_ES3
+// OpenGL ES 3
 #include <GLES3/gl3.h>  // Use GL ES 3
 #else
-// About OpenGL function loaders:
-// Modern OpenGL requires individual functions to be loaded manually. Helper libraries are often used for this purpose.
-// Here we are using gl3w.h, which requires a call to gl3wInit(). 
-// You may use another any other loader/header of your choice, such as glew, glext, glad, glLoadGen, etc.
+// OpenGL Regular
+// (About OpenGL function loaders: modern OpenGL doesn't have a standard header file and requires individual functions to be loaded manually. 
+//  Helper libraries are often used for this purpose! Here we are using gl3w.h, which requires a call to gl3wInit(). 
+//  You may use another any other loader/header of your choice, such as glew, glext, glad, glLoadGen, etc.)
 #include <GL/gl3w.h>
 //#include <glew.h>
 //#include <glext.h>
@@ -86,8 +94,13 @@ static unsigned int g_VboHandle = 0, g_ElementsHandle = 0;
 bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
 {
     // Store GLSL version string so we can refer to it later in case we recreate shaders. Note: GLSL version is NOT the same as GL version. Leave this to NULL if unsure.
+#ifdef USE_GL_ES3
+    if (glsl_version == NULL)
+        glsl_version = "#version 300 es";
+#else
     if (glsl_version == NULL)
         glsl_version = "#version 130";
+#endif
     IM_ASSERT((int)strlen(glsl_version) + 2 < IM_ARRAYSIZE(g_GlslVersionString));
     strcpy(g_GlslVersionString, glsl_version);
     strcat(g_GlslVersionString, "\n");

examples/imgui_impl_opengl3.h

@@ -1,4 +1,4 @@
-// ImGui Renderer for: OpenGL3 (modern OpenGL with shaders / programmatic pipeline)
+// ImGui Renderer for: OpenGL3 / OpenGL ES2 / OpenGL ES3 (modern OpenGL with shaders / programmatic pipeline)
 // This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)
 // (Note: We are using GL3W as a helper library to access OpenGL functions since there is no standard header to access modern OpenGL functions easily. Alternatives are GLEW, Glad, etc..)
 
@@ -15,8 +15,9 @@
 // You may use another any other loader/header of your choice, such as glew, glext, glad, glLoadGen, etc.
 
 // About GLSL version:
-// The 'glsl_version' initialization parameter defaults to "#version 130" if NULL.
-// Only override if your GL version doesn't handle this GLSL version (see table at the top of imgui_impl_opengl3.cpp). Keep NULL if unsure!
+// The 'glsl_version' initialization parameter should be NULL (default) or a "#version XXX" string.
+// On computer platform the GLSL version default to "#version 130". On OpenGL ES 3 platform it defaults to "#version 300 es"
+// Only override if your GL version doesn't handle this GLSL version. See GLSL version table at the top of imgui_impl_opengl3.cpp.
 
 IMGUI_IMPL_API bool     ImGui_ImplOpenGL3_Init(const char* glsl_version = NULL);
 IMGUI_IMPL_API void     ImGui_ImplOpenGL3_Shutdown();

imgui.cpp

@@ -13929,8 +13929,9 @@ void ImGui::EndDragDropTarget()
 //-----------------------------------------------------------------------------
 
 #if defined(_WIN32) && !defined(_WINDOWS_) && (!defined(IMGUI_DISABLE_WIN32_DEFAULT_CLIPBOARD_FUNCTIONS) || !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS))
-#undef WIN32_LEAN_AND_MEAN
+#ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
+#endif
 #ifndef __MINGW32__
 #include <Windows.h>
 #else