OpenGL related build problems on master branch (Batocera / Buildroot)

[nuumio]

I tried bumping Amiberry to latest master on my own Batocera (buildroot based) build and ran into this:

/rk3399/host/bin/aarch64-buildroot-linux-gnu-g++ -march=armv8-a+crc+crypto -mcpu=cortex-a53 -pipe -Wno-shift-overflow -Wno-narrowing -O3  -std=gnu++17 -MD -MT guisan -MF guisan -I/rk3399/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../../usr/include/SDL2 -D_REENTRANT -Iexternal/libguisan/include -Isrc -Isrc/osdep -Isrc/threaddep -Isrc/include -Isrc/archivers -Isrc/floppybridge -DAMIBERRY -D_FILE_OFFSET_BITS=64 -DCPU_AARCH64 -I./include -I/rk3399/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../../usr/include/SDL2 -D_REENTRANT -MD -MT src/opengl/opengl.o -MF src/opengl/opengl.d  -c -o src/opengl/opengl.o src/opengl/opengl.cpp
/rk3399/host/bin/aarch64-buildroot-linux-gnu-g++ -march=armv8-a+crc+crypto -mcpu=cortex-a53 -pipe -Wno-shift-overflow -Wno-narrowing -O3  -std=gnu++17 -MD -MT guisan -MF guisan -I/rk3399/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../../usr/include/SDL2 -D_REENTRANT -Iexternal/libguisan/include -Isrc -Isrc/osdep -Isrc/threaddep -Isrc/include -Isrc/archivers -Isrc/floppybridge -DAMIBERRY -D_FILE_OFFSET_BITS=64 -DCPU_AARCH64 -I./include -I/rk3399/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../../usr/include/SDL2 -D_REENTRANT -MD -MT src/opengl/openglgraphics.o -MF src/opengl/openglgraphics.d  -c -o src/opengl/openglgraphics.o src/opengl/openglgraphics.cpp
In file included from ./include/guisan/opengl.hpp:61,
                 from src/opengl/opengl.cpp:61:
./include/guisan/opengl/openglimage.hpp:73:10: fatal error: GL/gl.h: No such file or directory
   73 | #include <GL/gl.h>
      |          ^~~~~~~~~
compilation terminated.
make[2]: *** [<builtin>: src/opengl/opengl.o] Error 1
make[2]: *** Waiting for unfinished jobs....
/rk3399/host/bin/aarch64-buildroot-linux-gnu-g++ -march=armv8-a+crc+crypto -mcpu=cortex-a53 -pipe -Wno-shift-overflow -Wno-narrowing -O3  -std=gnu++17 -MD -MT src/inputdevice.o -MF src/inputdevice.d -I/rk3399/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../../usr/include/SDL2 -D_REENTRANT -Iexternal/libguisan/include -Isrc -Isrc/osdep -Isrc/threaddep -Isrc/include -Isrc/archivers -Isrc/floppybridge -DAMIBERRY -D_FILE_OFFSET_BITS=64 -DCPU_AARCH64  -c -o src/inputdevice.o src/inputdevice.cpp
/rk3399/host/bin/aarch64-buildroot-linux-gnu-g++ -march=armv8-a+crc+crypto -mcpu=cortex-a53 -pipe -Wno-shift-overflow -Wno-narrowing -O3  -std=gnu++17 -MD -MT src/inputrecord.o -MF src/inputrecord.d -I/rk3399/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../../usr/include/SDL2 -D_REENTRANT -Iexternal/libguisan/include -Isrc -Isrc/osdep -Isrc/threaddep -Isrc/include -Isrc/archivers -Isrc/floppybridge -DAMIBERRY -D_FILE_OFFSET_BITS=64 -DCPU_AARCH64  -c -o src/inputrecord.o src/inputrecord.cpp
/rk3399/host/bin/aarch64-buildroot-linux-gnu-g++ -march=armv8-a+crc+crypto -mcpu=cortex-a53 -pipe -Wno-shift-overflow -Wno-narrowing -O3  -std=gnu++17 -MD -MT src/isofs.o -MF src/isofs.d -I/rk3399/host/aarch64-buildroot-linux-gnu/sysroot/usr/bin/../../usr/include/SDL2 -D_REENTRANT -Iexternal/libguisan/include -Isrc -Isrc/osdep -Isrc/threaddep -Isrc/include -Isrc/archivers -Isrc/floppybridge -DAMIBERRY -D_FILE_OFFSET_BITS=64 -DCPU_AARCH64  -c -o src/isofs.o src/isofs.cpp
src/opengl/openglgraphics.cpp:74:10: fatal error: GL/gl.h: No such file or directory
   74 | #include <GL/gl.h>
      |          ^~~~~~~~~
compilation terminated.

It seems that changes in b6e94d5 cause it. The reason why GL/gl.h is not found is that Mesa3d in buildroot provides libgl only "for a full xorg stack" (https://github.com/batocera-linux/buildroot/blob/br2-external/package/mesa3d/mesa3d.mk#L187) and Batocera doesn't use xorg.

Changing #include <OpenGL/gl.h> includes back to #include <SDL_opengl.h> fixes the build for me and Amiberry seems to work:

diff --git a/external/libguisan/include/guisan/opengl/openglimage.hpp b/external/libguisan/include/guisan/opengl/openglimage.hpp
index 485fea30..3df29c8d 100644
--- a/external/libguisan/include/guisan/opengl/openglimage.hpp
+++ b/external/libguisan/include/guisan/opengl/openglimage.hpp
@@ -70,7 +70,7 @@
 #elif defined (__APPLE__)
 #include <OpenGL/gl.h>
 #else
-#include <GL/gl.h>
+#include <SDL_opengl.h>
 #endif
 
 #include <string>
diff --git a/external/libguisan/src/opengl/openglgraphics.cpp b/external/libguisan/src/opengl/openglgraphics.cpp
index 700626d5..c2436a31 100644
--- a/external/libguisan/src/opengl/openglgraphics.cpp
+++ b/external/libguisan/src/opengl/openglgraphics.cpp
@@ -71,7 +71,7 @@
 #elif defined(__APPLE__)
 #include <OpenGL/gl.h>
 #else
-#include <GL/gl.h>
+#include <SDL_opengl.h>
 #endif
 
 #include "guisan/exception.hpp"

I don't really have experience with graphics stacks so I thought to ask advice here for resolving this. At the moment it seems to boil down to these options:

1. Change SDL_opengl.h include back like described above. We could add a new flag to Makefile for this keeping #include <GL/gl.h> is preferred (something like USE_SDL_OPENGL maybe). So GL/gl.h would be included by default and SDL_opengl.h if set so by the new flag. I can make a PR for this.
2. Add above patch to Batocera's build when they bump Amiberry version (probably after next Amiberry version release). This is, of course, job for Batocera devs or for me.

I'm good with either option 🙂 Any opinions or suggestions about this?

[midwan]

Ah, sorry about that. I've been trying to get some things harmonized with the openGL target I have as an experiment, in the dev branch. I'll change those references to SDL_opengl.h if there's no impact.

[midwan]

fixed with 6a97a01

[nuumio]

No worries 🙂 Just tried latest master again and I can verify that it works again. Thanks for the quick fix!