Add cool rainbow effects

core/src/main/kotlin/com/last/commit/ColorState.kt

@@ -0,0 +1,43 @@
+package com.last.commit;
+
+class ColorState {
+    public var red = 0f
+    private set;
+    
+    public var green = 0f
+    private set;
+
+    public var blue = 1f
+    private set;
+
+    private var state = 0
+    
+    public fun step(delta: Long) {
+        val diff = delta / 5000f
+
+        when (state) {
+            0 -> {
+                blue -= diff;
+                red += diff
+                if (red >= 1f) {
+                    state = 1
+                }
+            }
+            1 -> {
+                red -= diff
+                green += diff
+                if (green >= 1f) {
+                    state = 2
+                }
+            }
+            2 -> {
+                green -= diff
+                blue += diff
+                if (blue >= 1f) {
+                    state = 0
+                }
+            }
+        }
+    }
+    
+}

core/src/main/kotlin/com/last/commit/FirstScreen.kt

@@ -1,15 +1,22 @@
 package com.last.commit
 
+import com.badlogic.gdx.Gdx
 import com.badlogic.gdx.Screen
+import com.badlogic.gdx.graphics.GL20
 
 /** First screen of the application. Displayed after the application is created.  */
 class FirstScreen : Screen {
+    val state = ColorState();
+
     override fun show() {
         // Prepare your screen here.
     }
 
     override fun render(delta: Float) {
+        state.step((delta * 1000).toLong())
         // Draw your screen here. "delta" is the time since last render in seconds.
+        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT)
+        Gdx.gl.glClearColor(state.red, state.green, state.blue, 1f)
     }
 
     override fun resize(width: Int, height: Int) {

core/src/main/kotlin/com/last/commit/Game.kt

@@ -4,6 +4,7 @@ import com.badlogic.gdx.Game
 
 /** [com.badlogic.gdx.ApplicationListener] implementation shared by all platforms.  */
 class Game : Game() {
+
     override fun create() {
         setScreen(FirstScreen())
     }