Header containing GLSL source code is generated only after change of any of shader source files.

CMakeModules/Shaders.cmake

@@ -4,6 +4,19 @@
 # number of input files
 list( LENGTH inputFiles shadersNumber ) 
 
+# check if GLSL source files were updated since the last time
+set( update "FALSE" )
+foreach( inputFile ${inputFiles} )
+    if( ${inputFile} IS_NEWER_THAN ${outputFile} )
+        set( update "TRUE" )
+    endif( ${inputFile} IS_NEWER_THAN ${outputFile} )
+endforeach( inputFile ${inputFiles} )
+
+if( NOT update )
+    message( "Headers are up-to-date" )
+    return()
+endif( NOT update )
+
 # write header
 file( WRITE ${outputFile} "// Do not edit this file, it is autogenerated by CMake.
 
@@ -14,28 +27,27 @@ const unsigned int shaders_number = ${shadersNumber};
 const char *shaders_src[] = {\n" )
 
 foreach( inputFile ${inputFiles} )
-	# put the input file name into the output file
-	file( APPEND ${outputFile} "\n// ${inputFile}" )
-	
-	# process the input file
-	file( READ ${inputFile} contents )
-	
-	# remove /* */ comments
-	string( REGEX REPLACE "/\\*.*\\*/" "" contents "${contents}" )
-	# remove // comments
-	string( REGEX REPLACE "//[^\n]*" "" contents "${contents}" )
-	# remove whitespaces at the beginning of each line
-	string( REGEX REPLACE "\n([\t ])*" "\n" contents "${contents}" )
-	# remove unnecessary spaces
-	string( REGEX REPLACE " *([\\*/+&\\|,=<>\(\)]) *" "\\1" contents "${contents}" )
-	# remove empty lines & wrap every line in "" and add '\n' at the end of each line	
-	string( REGEX REPLACE "\n+" "\\\\n\"\n\"" contents "${contents}" )
-	# remove unnecessary " & \n from the beginning and the end of contents
-	string( REGEX REPLACE "^\\\\n\"" "" contents "${contents}" )
-	string( REGEX REPLACE "\"$" "," contents "${contents}" )
-
-	file( APPEND ${outputFile} "${contents}" )
-
+    # put the input file name into the output file
+    file( APPEND ${outputFile} "\n// ${inputFile}" )
+
+    # process the input file
+    file( READ ${inputFile} contents )
+
+    # remove /* */ comments
+    string( REGEX REPLACE "/\\*.*\\*/" "" contents "${contents}" )
+    # remove // comments
+    string( REGEX REPLACE "//[^\n]*" "" contents "${contents}" )
+    # remove whitespaces at the beginning of each line
+    string( REGEX REPLACE "\n([\t ])*" "\n" contents "${contents}" )
+    # remove unnecessary spaces
+    string( REGEX REPLACE " *([\\*/+&\\|,=<>\(\)]) *" "\\1" contents "${contents}" )
+    # remove empty lines & wrap every line in "" and add '\n' at the end of each line	
+    string( REGEX REPLACE "\n+" "\\\\n\"\n\"" contents "${contents}" )
+    # remove unnecessary " & \n from the beginning and the end of contents
+    string( REGEX REPLACE "^\\\\n\"" "" contents "${contents}" )
+    string( REGEX REPLACE "\"$" "," contents "${contents}" )
+
+    file( APPEND ${outputFile} "${contents}" )
 endforeach( inputFile ${inputFiles} )
 
 # write footer