SDL alpha bleeds into the imgui windows

[RosculescuCiprian]

Version: 1.73 (17300)
Branch: master

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_opengl3.cpp + imgui_impl_sdl.cpp
Compiler: Visual Studio 2019 (MSVC)
Operating System: Windows 10 Home (1809)

My Issue/Question:

When setting windows opacity for an sdl window then the opacity is transferred through the imgui windows. I am using only the examples from the github examples folder

Result

The expected result is just the imgui windows to be opaque

NOTE
This issue is the sdl equivalent for #2764 but the solutions that have worked there do not work here. See the examples

Standalone, minimal, complete and verifiable example:

These are the options that i tried from the examples in the repository

All the variants from imgui_impl_opengl3.cpp

function ImGui_ImplOpenGL3_SetupRenderState

glEnable(GL_BLEND); //glBlendEquation(GL_FUNC_ADD); glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX); glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA); //glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glEnable(GL_BLEND); //glBlendEquation(GL_FUNC_ADD); glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX); glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glEnable(GL_BLEND); glBlendEquation(GL_FUNC_ADD); //glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX); //glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glEnable(GL_BLEND); glBlendEquation(GL_FUNC_ADD); //glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX); glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA); //glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

In the main.cpp
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8); SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI); SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags); SDL_GLContext gl_context = SDL_GL_CreateContext(window); SDL_SetWindowOpacity(window, 0.8f);

Any help with this issue is welcome.
Thank you.

[ocornut]

Linking to #2764, #2693 in case they may be related (note, haven't checked the issue in details at all).

[ocornut]

Hello @RosculescuCiprian

Went through a bunch of backends and examples yesterday.
Fixed this with bda12e5 and 6a161b8 (we have 7 open issues related to this).