Extract offset modifier to a variable

src/main.cc

@@ -42,6 +42,7 @@ struct App {
   // OpenGL refers to as element, hence the name Element Buffer Object
   GLuint        ebo;
 
+  float         offset_modifier;
   // offset value passed to shaders as uniform
   float         offset;
   // offset uniform index
@@ -119,6 +120,8 @@ int init(App &app) {
          glGetString(GL_SHADING_LANGUAGE_VERSION)
   );
 
+	app.offset_modifier = 0.02f;
+
   return EXIT_CODE_SUCCESS;
 }
 
@@ -216,9 +219,9 @@ void run_main_loop(App &app) {
         break;
       case SDL_KEYDOWN:
         if (app.event.key.keysym.sym == SDLK_UP) {
-          app.offset += 0.01f;
+          app.offset += app.offset_modifier;
         } else if (app.event.key.keysym.sym == SDLK_DOWN) {
-          app.offset -= 0.01f;
+          app.offset -= app.offset_modifier;
         }
       }
     }