project file allow installation in another dir than "/usr"

E.g. this way I can build and install in "~/.local", or "/usr/local".

app/app.pro

@@ -19,20 +19,26 @@ RESOURCES += qml/resources.qrc
 ##              INSTALLS
 #########################################
 
-target.path += /usr/bin/
+PREFIX = $$(PREFIX) # Pass the make install PREFIX via environment variable. E.g. "PREFIX=/path/to/my/dir qmake".
+isEmpty(PREFIX) {
+    message(No prefix given. Using /usr.)
+    PREFIX=/usr
+}
+
+target.path = $$PREFIX/bin
 
 INSTALLS += target
 
 # Install icons
 unix {
     icon32.files = icons/32x32/cool-retro-term.png
-    icon32.path = /usr/share/icons/hicolor/32x32/apps
+    icon32.path = $$PREFIX/share/icons/hicolor/32x32/apps
     icon64.files = icons/64x64/cool-retro-term.png
-    icon64.path = /usr/share/icons/hicolor/64x64/apps
+    icon64.path = $$PREFIX/share/icons/hicolor/64x64/apps
     icon128.files = icons/128x128/cool-retro-term.png
-    icon128.path = /usr/share/icons/hicolor/128x128/apps
+    icon128.path = $$PREFIX/share/icons/hicolor/128x128/apps
     icon256.files = icons/256x256/cool-retro-term.png
-    icon256.path = /usr/share/icons/hicolor/256x256/apps
+    icon256.path = $$PREFIX/share/icons/hicolor/256x256/apps
 
     INSTALLS += icon32 icon64 icon128 icon256
 }

app/qml/ShaderTerminal.qml

@@ -247,6 +247,17 @@ Item {
              "  return outColor;
              }" +
 
+             //pseudo-random vector
+             //https://stackoverflow.com/a/10625698
+             "float random( vec2 p )
+             {
+                 vec2 K1 = vec2(
+                     23.14069263277926, // e^pi (Gelfond's constant)
+                     2.665144142690225 // 2^sqrt(2) (Gelfond-Schneider constant)
+                 );
+                 return fract( cos( dot(p,K1) ) * 12345.6789 );
+             }" +
+
              "void main() {" +
                  "vec2 cc = vec2(0.5) - qt_TexCoord0;" +
                  "float distance = length(cc);" +
@@ -285,7 +296,11 @@ Item {
                  : "") +
 
                  (jitter !== 0 || staticNoise !== 0 ?
-                     "vec4 noiseTexel = texture2D(noiseSource, scaleNoiseSize * coords + vec2(fract(time / 51.0), fract(time / 237.0)));"
+                 "vec4 noiseTexel = texture2D(
+                     noiseSource, scaleNoiseSize * coords
+                     + vec2(0.0, random(vec2(fract(time / 237.0), 822.9582)))
+                     + vec2(fract(time / 31.0), fract(time / 177.0))
+                 );"
                  : "") +
 
                  (jitter !== 0 ? "

cool-retro-term.pro

@@ -5,7 +5,17 @@ CONFIG += ordered
 SUBDIRS += qmltermwidget
 SUBDIRS += app
 
+#########################################
+##              INSTALLS
+#########################################
+
+PREFIX = $$(PREFIX) # Pass the make install PREFIX via environment variable. E.g. "PREFIX=/path/to/my/dir qmake".
+isEmpty(PREFIX) {
+    message(No prefix given. Using /usr.)
+    PREFIX=/usr
+}
+
 desktop.files += cool-retro-term.desktop
-desktop.path += /usr/share/applications
+desktop.path += $$PREFIX/share/applications
 
 INSTALLS += desktop