[Bug] Build error on system with GLES3: use of undeclared identifier `GL_SRC1_COLOR`

[leha-bot]

Operating System

Linux

What's the issue you encountered?

The file <GLES3/gl3.h> used here:

ImHex/lib/third_party/imgui/backend/source/imgui_impl_opengl3.cpp

Line 175 in 03dd20c

#include <GLES3/gl3.h> // Use GL ES 3

- doesn't contain this GLES identifier (it seems GLES doesn't support the Dual-Source blending, as WebGL (and Emscripten) doesn't support it either). I think the possible fix is to disable this patch for GLES2/3 at this line:

ImHex/lib/third_party/imgui/backend/source/imgui_impl_opengl3.cpp

Line 486 in 03dd20c

#if !defined(__EMSCRIPTEN__)

I'll make a PR with this fix.

How can the issue be reproduced?

1. Set IMGUI_IMPL_OPENGL_ES3 #define to 1 (e.g., via CMake, or build on specific Linux-like environment (e.g., termux)
2. Try to build
3. Get this error:

Building CXX object lib/third_party/imgui/backend/CMakeFiles/imgui_backend.dir/source/imgui_impl_opengl3.cpp.o
/data/data/com.termux/files/home/ImHex/lib/third_party/imgui/backend/source/imgui_impl_opengl3.cpp:488:29: error:
      use of undeclared identifier 'GL_SRC1_COLOR'
  488 |         glBlendFuncSeparate(GL_SRC1_COLOR, GL_ONE_MINUS_SRC1_COLOR,G...
      |                             ^~~~~
/data/data/com.termux/files/home/ImHex/lib/third_party/imgui/backend/source/imgui_impl_opengl3.cpp:488:44: error:
      use of undeclared identifier 'GL_ONE_MINUS_SRC1_COLOR'
  488 |         glBlendFuncSeparate(GL_SRC1_COLOR, GL_ONE_MINUS_SRC1_COLOR,G...
      |                                            ^~~~~~~
2 errors generated.
make[3]: *** [lib/third_party/imgui/backend/CMakeFiles/imgui_backend.dir/build.make:79: lib/third_party/imgui/backend/CMakeFiles/imgui_backend.dir/source/imgui_impl_opengl3.cpp.o] Error 1
make[2]: *** [CMakeFiles/Makefile2:3243: lib/third_party/imgui/backend/CMakeFiles/imgui_backend.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:3250: lib/third_party/imgui/backend/CMakeFiles/imgui_backend.dir/rule] Error 2
make: *** [Makefile:524: imgui_backend] Error 2

ImHex Version

1.39.0.WIP (hash: 03dd20c)

ImHex Build Type

• Nightly or built from sources

Installation type

build from source

Additional context?

No response

[paxcut]

AFAIK gles3 is not supported in ImHex so you shouldn't be having this error.

[leha-bot]

Agreed, but this error, unfortunately, exists if you ,e.g., build ImHex on Android itself

[paxcut]

To run ImHex on a phone you need to use the Emscripten version because webgl is probably going to have lots of problems if you try to run it. That is my understanding at least but i could be wrong.

[iTrooz]

@leha-bot Hey, please don't hesitate to join the discord, I'd love to know more about what you are doing

[iTrooz]

I could see the OS_WEB / __EMSCRIPTEN__ macros being replaced by USE_GLES3, since (if I understand correctly ?) we already use GLES3 on the web version

[WerWolv]

Using #if defined(IMGUI_IMPL_OPENGL_ES2) || defined(IMGUI_IMPL_OPENGL_ES3) instead of #if defined(__EMSCRIPTEN__) would be absolutely fine with me. That should make it all work with other systems too that only support GLES

[iTrooz]

GLES2 ? I thought ImHex needed OpenGL3 minimum ?

[WerWolv]

I thought the web version used GLES2 but maybe I'm wrong. If it's using GLES3 then #if defined(IMGUI_IMPL_OPENGL_ES3) only is fine

[paxcut]

Why do we even need to support GLES 2 or 3 directly? Isn't using Emscripten to build the web app allow ImHex to run on any browser?

[iTrooz]

Yeah, but changing the macro isn't hard for us, so why not if it can help people

[WerWolv]

Yeah, the more support the better :) Especially when it requires basically no effort from our side to do it

[paxcut]

Are these macros provided by the ImGui GLES implementation and the Emscripten compiler or are they macros we have crated to separate the different types of builds we do? If we support Gles 2 or 3 why don't we use the macros for it already? Nobody asked before?

[WerWolv]

They're provided by ImGui, I simply didn't know about them until now