minor refactor

src/coders/GLSLExtension.cpp

@@ -76,6 +76,14 @@ void GLSLExtension::undefine(const std::string& name) {
     }
 }
 
+void GLSLExtension::setDefined(const std::string& name, bool defined) {
+    if (defined) {
+        define(name, "TRUE");
+    } else {
+        undefine(name);
+    }
+}
+
 inline std::runtime_error parsing_error(
     const io::path& file, uint linenum, const std::string& message
 ) {

src/coders/GLSLExtension.hpp

@@ -22,6 +22,7 @@ public:
 
     void define(const std::string& name, std::string value);
     void undefine(const std::string& name);
+    void setDefined(const std::string& name, bool defined);
     void addHeader(const std::string& name, ProcessingResult header);
 
     const ProcessingResult& getHeader(const std::string& name) const;