diff -ur OpenCSG-1.4.2-pristine/example/example.pro OpenCSG-1.4.2/example/example.pro
--- OpenCSG-1.4.2-pristine/example/example.pro	2016-09-27 06:11:16.000000000 +0900
+++ OpenCSG-1.4.2/example/example.pro	2019-05-07 10:45:18.785251737 +0900
@@ -6,7 +6,9 @@
 INCLUDEPATH += ../include
 LIBS += -L../lib -lopencsg -lGLEW
 
-INSTALLDIR = /usr/local
+isEmpty(INSTALLDIR) {
+  INSTALLDIR = /usr/local
+}
 INSTALLS += target
 target.path = $$INSTALLDIR/bin
 
diff -ur OpenCSG-1.4.2-pristine/opencsg.pro OpenCSG-1.4.2/opencsg.pro
--- OpenCSG-1.4.2-pristine/opencsg.pro	2016-09-27 06:11:16.000000000 +0900
+++ OpenCSG-1.4.2/opencsg.pro	2019-05-07 10:44:50.578698165 +0900
@@ -1,2 +1,3 @@
 TEMPLATE = subdirs
 SUBDIRS  = src example
+CONFIG   += ordered