Backends: OpenGL2, OpenGL3: ImGui_ImplOpenGL3_NewFrame() recreates font texture if it has been destroyed by ImGui_ImplOpenGL3_DestroyFontsTexture(). (#7748)

Analogous to change to Vulkan backend in 1.90.

backends/imgui_impl_opengl2.cpp

@@ -22,6 +22,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-06-28: OpenGL: ImGui_ImplOpenGL2_NewFrame() recreates font texture if it has been destroyed by ImGui_ImplOpenGL2_DestroyFontsTexture(). (#7748)
 //  2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11.
 //  2021-12-08: OpenGL: Fixed mishandling of the ImDrawCmd::IdxOffset field! This is an old bug but it never had an effect until some internal rendering changes in 1.86.
 //  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).
@@ -113,6 +114,8 @@ void    ImGui_ImplOpenGL2_NewFrame()
 
     if (!bd->FontTexture)
         ImGui_ImplOpenGL2_CreateDeviceObjects();
+    if (!bd->FontTexture)
+        ImGui_ImplOpenGL2_CreateFontsTexture();
 }
 
 static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height)

backends/imgui_impl_opengl3.cpp

@@ -22,6 +22,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-06-28: OpenGL: ImGui_ImplOpenGL3_NewFrame() recreates font texture if it has been destroyed by ImGui_ImplOpenGL3_DestroyFontsTexture(). (#7748)
 //  2024-05-07: OpenGL: Update loader for Linux to support EGL/GLVND. (#7562)
 //  2024-04-16: OpenGL: Detect ES3 contexts on desktop based on version string, to e.g. avoid calling glPolygonMode() on them. (#7447)
 //  2024-01-09: OpenGL: Update GL3W based imgui_impl_opengl3_loader.h to load "libGL.so" and variants, fixing regression on distros missing a symlink.
@@ -402,6 +403,8 @@ void    ImGui_ImplOpenGL3_NewFrame()
 
     if (!bd->ShaderHandle)
         ImGui_ImplOpenGL3_CreateDeviceObjects();
+    if (!bd->FontTexture)
+        ImGui_ImplOpenGL3_CreateFontsTexture();
 }
 
 static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height, GLuint vertex_array_object)

docs/CHANGELOG.txt

@@ -90,6 +90,8 @@ Other changes:
 - Debug Tools: Metrics/Debugger: Browsing a Storage perform hover lookup on identifier.
 - Viewports: Backported 'void* ImGuiViewport::PlatformHandle' from docking branch for
   use by backends.
+- Backends: OpenGL2, OpenGL3: ImGui_ImplOpenGL3_NewFrame() recreates font texture if it
+  has been destroyed by ImGui_ImplOpenGL3_DestroyFontsTexture(). (#7748) [@mlauss2]
 - Backends: SDL3: Update for API removal of keysym field in SDL_KeyboardEvent. (#7728)
 - Backends: SDL3: Update for SDL_StartTextInput()/SDL_StopTextInput() API changes. (#7735)
 - Backends: Vulkan: Remove Volk/ from volk.h #include directives. (#7722, #6582, #4854)