build: make sdl2 and rototiller bin optional

Now that there's a decoupled libtil usable by alternative
frontends by vendoring rototiller, the build should support
fb-less rototiller-less configurations.

In lieu of this change glimmer's build requires sdl2 despite not
actually utilizing sdl_fb.  Now that shouldn't be necessary,
should there be neither libdrm or sdl2 present we'll only produce
libtil and no rototiller binary at all.

3 files changed, 27 insertions, 16 deletions

diff --git a/configure.ac b/configure.ac
index 3abca76..974b33d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -8,29 +8,27 @@ AM_SILENT_RULES([yes])
 LT_INIT([disable-shared])
 
 PKG_CHECK_MODULES(DRM, libdrm,
-	AM_CONDITIONAL(ENABLE_DRM, true)
+	AM_CONDITIONAL(ENABLE_DRM, declare build_rototiller=true)
 	AC_DEFINE(HAVE_DRM, [1], [Define to 1 with drm present]),
 	AM_CONDITIONAL(ENABLE_DRM, false)
 )
 
-LIBS="$DRM_LIBS $LIBS"
-CFLAGS="$DRM_CFLAGS $CFLAGS"
+PKG_CHECK_MODULES(SDL, sdl2,
+	AM_CONDITIONAL(ENABLE_SDL, declare build_rototiller=true)
+	AC_DEFINE(HAVE_SDL, [1], [Define to 1 with sdl2 present]),
+	AM_CONDITIONAL(ENABLE_SDL, false)
+)
+
+AM_CONDITIONAL(ENABLE_ROTOTILLER, [test "x$build_rototiller" = xtrue])
+
+LIBS="$DRM_LIBS $SDL_LIBS $LIBS"
+CFLAGS="$DRM_CFLAGS $SDL_CFLAGS $CFLAGS"
 
 AX_PTHREAD
 LIBS="$PTHREAD_LIBS $LIBS"
-CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+CFLAGS="$PTHREAD_CFLAGS $CFLAGS"
 CC="$PTHREAD_CC"
 
-dnl Check for SDL
-SDL_VERSION=2.0
-AM_PATH_SDL2($SDL_VERSION,
-	:,
-	AC_MSG_ERROR([*** SDL version $SDL_VERSION not found!])
-)
-
-CFLAGS="$CFLAGS $SDL_CFLAGS"
-LIBS="$LIBS $SDL_LIBS"
-
 AC_CONFIG_FILES([
  Makefile
  src/Makefile
diff --git a/src/Makefile.am b/src/Makefile.am
index 6ca1d77..aa42c08 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -5,9 +5,14 @@ libtil_la_SOURCES = til_args.c til_args.h til_fb.c til_fb.h til_knobs.h til.c ti
 libtil_la_CPPFLAGS = -I@top_srcdir@/src
 libtil_la_LIBADD = modules/compose/libcompose.la modules/drizzle/libdrizzle.la modules/flui2d/libflui2d.la modules/julia/libjulia.la modules/meta2d/libmeta2d.la modules/montage/libmontage.la modules/pixbounce/libpixbounce.la modules/plasma/libplasma.la modules/plato/libplato.la modules/ray/libray.la modules/roto/libroto.la modules/rtv/librtv.la modules/snow/libsnow.la modules/sparkler/libsparkler.la modules/spiro/libspiro.la modules/stars/libstars.la modules/submit/libsubmit.la modules/swab/libswab.la modules/swarm/libswarm.la libs/grid/libgrid.la libs/puddle/libpuddle.la libs/ray/libray.la libs/sig/libsig.la libs/txt/libtxt.la libs/ascii/libascii.la libs/din/libdin.la
 
+if ENABLE_ROTOTILLER
 bin_PROGRAMS = rototiller
-rototiller_SOURCES = fps.c fps.h main.c sdl_fb.c setup.h setup.c til.h til_fb.c til_fb.h til_knobs.h til_settings.c til_settings.h til_threads.c til_threads.h til_util.c til_util.h
+rototiller_SOURCES = fps.c fps.h main.c setup.h setup.c til.h til_fb.c til_fb.h til_knobs.h til_settings.c til_settings.h til_threads.c til_threads.h til_util.c til_util.h
+if ENABLE_SDL
+rototiller_SOURCES += sdl_fb.c
+endif
 if ENABLE_DRM
 rototiller_SOURCES += drm_fb.c
 endif
 rototiller_LDADD = libtil.la -lm
+endif
diff --git a/src/main.c b/src/main.c
index c6b0362..c19b6b5 100644
--- a/src/main.c
+++ b/src/main.c
@@ -27,7 +27,11 @@
  * another page so we can begin rendering another frame before vsync.  With
  * just two pages we end up twiddling thumbs until the vsync arrives.
  */
+#ifdef HAVE_SDL
 #define DEFAULT_VIDEO	"sdl"
+#else
+#define DEFAULT_VIDEO	"drm"
+#endif
 
 extern til_fb_ops_t	drm_fb_ops;
 extern til_fb_ops_t	sdl_fb_ops;
@@ -68,7 +72,9 @@ static int setup_video(til_settings_t *settings, til_setting_t **res_setting, co
 #ifdef HAVE_DRM
 						"drm",
 #endif
+#ifdef HAVE_SDL
 						"sdl",
+#endif
 						NULL,
 					};
 		int			r;
@@ -96,13 +102,15 @@ static int setup_video(til_settings_t *settings, til_setting_t **res_setting, co
 		fb_ops = &drm_fb_ops;
 
 		return drm_fb_ops.setup(settings, res_setting, res_desc);
-	} else
+	}
 #endif
+#ifdef HAVE_SDL
 	if (!strcmp(video, "sdl")) {
 		fb_ops = &sdl_fb_ops;
 
 		return sdl_fb_ops.setup(settings, res_setting, res_desc);
 	}
+#endif
 
 	return -EINVAL;
 }