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Backends: OpenGL3: Attempt to automatically detect default GL loader by using __has_include. Followup to 44cd8e3 (#2798)

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This commit is contained in:
omar
2019-09-22 23:19:04 +02:00
parent 44cd8e39da
commit 97691643b7
5 changed files with 70 additions and 35 deletions
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33
examples/imgui_impl_opengl3.cpp
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@ -1,5 +1,5 @@
// dear imgui: Renderer for modern OpenGL with shaders / programmatic pipeline
// - Desktop GL: 3.x 4.x
// - Desktop GL: 2.x 3.x 4.x
// - Embedded GL: ES 2.0 (WebGL 1.0), ES 3.0 (WebGL 2.0)
// This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)
@ -13,6 +13,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2019-09-22: OpenGL: Detect default GL loader using __has_include compiler facility.
// 2019-09-16: OpenGL: Tweak initialization code to allow application calling ImGui_ImplOpenGL3_CreateFontsTexture() before the first NewFrame() call.
// 2019-05-29: OpenGL: Desktop GL only: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
// 2019-04-30: OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
@ -79,12 +80,21 @@
// Auto-detect GL version
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3)
#if (defined(__APPLE__) && (TARGET_OS_IOS || TARGET_OS_TV)) || (defined(__ANDROID__))
#define IMGUI_IMPL_OPENGL_ES3 // iOS, Android -> GL ES 3, "#version 300 es"
#define IMGUI_IMPL_OPENGL_ES3 // iOS, Android -> GL ES 3, "#version 300 es"
#undef IMGUI_IMPL_OPENGL_LOADER_GL3W
#undef IMGUI_IMPL_OPENGL_LOADER_GLEW
#undef IMGUI_IMPL_OPENGL_LOADER_GLAD
#undef IMGUI_IMPL_OPENGL_LOADER_CUSTOM
#elif defined(__EMSCRIPTEN__)
#define IMGUI_IMPL_OPENGL_ES2 // Emscripten -> GL ES 2, "#version 100"
#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_CUSTOM
#endif
#endif
// GL includes
#if defined(IMGUI_IMPL_OPENGL_ES2)
#include <GLES2/gl2.h>
#elif defined(IMGUI_IMPL_OPENGL_ES3)
@ -149,6 +159,23 @@ bool ImGui_ImplOpenGL3_Init(const char* glsl_version)
strcpy(g_GlslVersionString, glsl_version);
strcat(g_GlslVersionString, "\n");
// Dummy construct to make it easily visible in the IDE and debugger which GL loader has been selected.
// The code actually never uses the 'gl_loader' variable! It is only here so you can read it!
// 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 below.
// You can explicitly select a loader by using '#define IMGUI_IMPL_OPENGL_LOADER_XXX' in imconfig.h or compiler command-line.
const char* gl_loader = "Unknown";
IM_UNUSED(gl_loader);
#if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
gl_loader = "GL3W";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
gl_loader = "GLEW";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
gl_loader = "GLAD";
#else IMGUI_IMPL_OPENGL_LOADER_CUSTOM
gl_loader = "Custom";
#endif
// Make a dummy GL call (we don't actually need the result)
// IF YOU GET A CRASH HERE: it probably means that you haven't initialized the OpenGL function loader used by this code.
// Desktop OpenGL 3/4 need a function loader. See the IMGUI_IMPL_OPENGL_LOADER_xxx explanation above.