[client] egl: generate header file with #define for desktop shader

Instead of duplicating the #defines from the shader into the C code,
this commit adds a custom CMake rule that exports all the #defines
from a shader into a C header.

client/cmake/MakeObject.cmake

@@ -32,3 +32,11 @@ function(make_object out_var)
   set(${out_var}_OBJS "${result}"   PARENT_SCOPE)
   set(${out_var}_INCS "${result_h}" PARENT_SCOPE)
 endfunction()
+
+function(make_defines in_file out_file)
+  add_custom_command(OUTPUT ${out_file}
+    COMMAND grep "^#define" "${in_file}" > "${out_file}"
+    DEPENDS ${in_file}
+    COMMENT "Creating #defines from ${in_file}"
+  )
+endfunction()

client/renderers/EGL/CMakeLists.txt

@@ -34,6 +34,11 @@ make_object(
 	shader/splash_logo.frag
 )
 
+make_defines(
+	"${CMAKE_CURRENT_SOURCE_DIR}/shader/desktop_rgb.frag"
+	"${CMAKE_CURRENT_BINARY_DIR}/shader/desktop_rgh.def.h"
+)
+
 add_library(renderer_EGL STATIC
 	egl.c
 	egldebug.c
@@ -48,6 +53,7 @@ add_library(renderer_EGL STATIC
 	splash.c
 	alert.c
 	${EGL_SHADER_OBJS}
+	"${EGL_SHADER_INCS}/desktop_rgh.def.h"
 )
 
 target_link_libraries(renderer_EGL

client/renderers/EGL/desktop.c

@@ -33,9 +33,7 @@ Place, Suite 330, Boston, MA 02111-1307 USA
 // these headers are auto generated by cmake
 #include "desktop.vert.h"
 #include "desktop_rgb.frag.h"
-
-#define LG_SCALE_NEAREST 0
-#define LG_SCALE_LINEAR  1
+#include "desktop_rgh.def.h"
 
 struct DesktopShader
 {