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Backends: OpenGL3: Embed our own minimal GL loader (amends). (#4445)

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ocornut
2021-08-19 15:27:22 +02:00
parent 459de65477
commit e3988a84db
15 changed files with 41 additions and 75 deletions
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26
backends/imgui_impl_opengl3.cpp
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@ -14,6 +14,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2021-08-19: OpenGL: Embed and use our own minimal GL loader (imgui_impl_opengl3_loader.h), removing requirement and support for third-party loader.
// 2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
// 2021-06-25: OpenGL: Use OES_vertex_array extension on Emscripten + backup/restore current state.
// 2021-06-21: OpenGL: Destroy individual vertex/fragment shader objects right after they are linked into the main shader.
@ -108,16 +109,15 @@
#else
#include <GLES3/gl3.h> // Use GL ES 3
#endif
#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 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 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
#elif !defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
// 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 using our own minimal custom loader based on gl3w.
// In the rest of your app/engine, you can use another loader of your choice (gl3w, glew, glad, glbinding, glext, glLoadGen, etc.).
// If you happen to be developing a new feature for this backend (imgui_impl_opengl3.cpp):
// - You may need to regenerate imgui_impl_opengl3_loader.h to add new symbols. See https://github.com/dearimgui/gl3w_stripped
// - You can temporarily use an unstripped version. See https://github.com/dearimgui/gl3w_stripped/releases
// Changes to this backend using new APIs should be accompanied by a regenerated stripped loader version.
#define IMGL3W_IMPL
#include "imgui_impl_opengl3_loader.h"
#endif
@ -188,6 +188,7 @@ bool ImGui_ImplOpenGL3_Init(const char* glsl_version)
ImGuiIO& io = ImGui::GetIO();
IM_ASSERT(io.BackendRendererUserData == NULL && "Already initialized a renderer backend!");
// Initialize our loader
#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3)
if (imgl3wInit() != 0)
{
@ -241,6 +242,11 @@ bool ImGui_ImplOpenGL3_Init(const char* glsl_version)
strcpy(bd->GlslVersionString, glsl_version);
strcat(bd->GlslVersionString, "\n");
// Make an arbitrary GL call (we don't actually need the result)
// IF YOU GET A CRASH HERE: it probably means the OpenGL function loader didn't do its job. Let us know!
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

5
backends/imgui_impl_opengl3.h
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@ -12,11 +12,6 @@
// If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
// Read online: https://github.com/ocornut/imgui/tree/master/docs
// 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).
// You may use another loader/header of your choice (glext, glLoadGen, etc.), or chose to manually implement your own.
// About GLSL version:
// 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"