Imgui: glfw dependency not needed for SDL examples

[acda]

Hi.

I like ImGui being free of unnecessary dependencies. But the Makefile of the SDL samples (gl2, gl3) hint that I need that lib.

In fact, they work nicely without as SDL provides all it needs.

Without changing anything in the source codes, and without installing glfw, I compiled and launched the samples with this single command-line:

gl3-example:
g++ -o sdl_opengl3_example -I../../ -I../libs/gl3w -I/usr/include/SDL2 -Wall -Wformat main.cpp imgui_impl_sdl_gl3.cpp ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp ../libs/gl3w/GL/gl3w.c -lSDL2 -ldl -lwayland-client -lasound -lGL -lpthread

gl2-example:

g++ -o sdl_opengl2_example -I../../ -I../libs/gl3w -I/usr/include/SDL2 -Wall -Wformat main.cpp imgui_impl_sdl.cpp ../../imgui.cpp ../../imgui_demo.cpp ../../imgui_draw.cpp ../libs/gl3w/GL/gl3w.c -lSDL2 -ldl -lwayland-client -lasound -lGL -lpthread

sorry I don't know makefiles so I could not provide a patch/fix for the makefile.

Would be cool to remove the dependencies to make it easier to build.

I used dynamic linking because SDL2 wants asound lib, and my Debian does not provide a static-link asound lib. only an .so

(note that I had to add -I/usr/include/SDL2 . why??)

[ebachard]

@acda

Looks like you're right : either glfw is used, or SDL2
About the SDL2 use : the advised way is to use sdl2-config --cflags --libs

Last, about the -I /usr/include/SDL2 is probably because there is #include and it the above -I is not used, the preprocessor will never resolve the #include . BTW, sdl2-config --cflagssolves this issue.

@ocornut

As solution (tested on my machine), I'd suggest what follows :

diff --git a/examples/sdl_opengl3_example/Makefile b/examples/sdl_opengl3_example/Makefile
index e4aee57..a237c1d 100644
--- a/examples/sdl_opengl3_example/Makefile
+++ b/examples/sdl_opengl3_example/Makefile
@@ -22,9 +22,9 @@ UNAME_S := $(shell uname -s)

 ifeq ($(UNAME_S), Linux) #LINUX
        ECHO_MESSAGE = "Linux"
-       LIBS = -lGL `pkg-config --static --libs glfw3`
+       LIBS = -lGL -ldl `sdl2-config --libs`

-       CXXFLAGS = -I../../ -I../libs/gl3w `pkg-config --cflags glfw3`
+       CXXFLAGS = -I../../ -I../libs/gl3w `sdl2-config --cflags`
        CXXFLAGS += -Wall -Wformat
        CFLAGS = $(CXXFLAGS)
 endif

My 2 cents

[ebachard]

I forgot : please notice the additional:
-ldl
Without it - on my machine, needs to be confirmed- I got a build issue saying :
/usr/bin/ld: ../libs/gl3w/GL/gl3w.o: undefined symbol reference «dlclose@@GLIBC_2.2.5»
//lib/x86_64-linux-gnu/libdl.so.2: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status

[ocornut]

Well, looks like that Makefile that I merged recently was wrong (I didn't test it) because the PR only tested for MINGW and not the other blocks.

It comes from:
https://github.com/ocornut/imgui/pull/1209

Could somebody try and test the Mac block?

I am going to add those samples projects on the Travis build setup too.

[ocornut]

Added this project to Travis and made it work for both Linux and OSX. Should be all fixed!