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Backends: OpenGL3: Embed our own minimal GL loader based on gl3w and use it in SDL/GLFW examples. (#4445)

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Loader repository at https://github.com/dearimgui/gl3w_stripped
Removed support for using custom loaders in examples/opengl3 backend
This commit is contained in:
Rokas Kupstys
2021-08-19 12:42:15 +03:00
committed by ocornut
parent 7bbf8f2ab0
commit 459de65477
15 changed files with 775 additions and 7393 deletions
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72
backends/imgui_impl_opengl3.cpp
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@ -111,33 +111,14 @@
#else
// About Desktop OpenGL function loaders:
// Modern desktop OpenGL doesn't have a standard portable header file to load OpenGL function pointers.
// Helper libraries are often used for this purpose! Here we are supporting a few common ones (gl3w, glew, glad).
// Helper libraries are often used for this purpose! Here we are using our own minimal custom loader based on gl3w.
// You may use another loader/header of your choice (glext, glLoadGen, etc.), or chose to manually implement your own.
#if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
#include <GL/gl3w.h> // Needs to be initialized with gl3wInit() in user's code
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
#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.
#endif
#include <glbinding/Binding.h> // Needs to be initialized with glbinding::Binding::initialize() in user's code.
#include <glbinding/gl/gl.h>
using namespace gl;
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)
#ifndef GLFW_INCLUDE_NONE
#define GLFW_INCLUDE_NONE // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
#endif
#include <glbinding/glbinding.h>// Needs to be initialized with glbinding::initialize() in user's code.
#include <glbinding/gl/gl.h>
using namespace gl;
#else
#include IMGUI_IMPL_OPENGL_LOADER_CUSTOM
#endif
// If you happen to be developing a new feature for this backend, you may want to get a unstripped version of
// imgui_impl_opengl3_loader.h from https://github.com/dearimgui/gl3w_stripped/releases/ and use that temporarily.
// When done, changes using new APIs should be accompanied by regenerated stripped loader version (instructions in
// gl3w_stripped README.rst).
#define IMGL3W_IMPL 1
#include "imgui_impl_opengl3_loader.h"
#endif
// Vertex arrays are not supported on ES2/WebGL1 unless Emscripten which uses an extension
@ -207,6 +188,14 @@ bool ImGui_ImplOpenGL3_Init(const char* glsl_version)
ImGuiIO& io = ImGui::GetIO();
IM_ASSERT(io.BackendRendererUserData == NULL && "Already initialized a renderer backend!");
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3)
if (imgl3wInit() != 0)
{
fprintf(stderr, "Failed to initialize OpenGL loader!\n");
return false;
}
#endif
// Setup backend capabilities flags
ImGui_ImplOpenGL3_Data* bd = IM_NEW(ImGui_ImplOpenGL3_Data)();;
io.BackendRendererUserData = (void*)bd;
@ -252,37 +241,6 @@ bool ImGui_ImplOpenGL3_Init(const char* glsl_version)
strcpy(bd->GlslVersionString, glsl_version);
strcat(bd->GlslVersionString, "\n");
// Debugging 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";
#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)
gl_loader = "glbinding3";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
gl_loader = "custom";
#else
gl_loader = "none";
#endif
// Make an arbitrary 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.
GLint current_texture;
glGetIntegerv(GL_TEXTURE_BINDING_2D, &current_texture);
// Detect extensions we support
bd->HasClipOrigin = (bd->GlVersion >= 450);
#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_EXTENSIONS