From 270ba3e4a7247de502260b5053919ccef5309b3a Mon Sep 17 00:00:00 2001
From: Victor <melnikukr@mail.ru>
Date: Wed, 15 Jan 2014 21:50:25 +0200
Subject: [PATCH] Add stars background

---
 .../annimon/influencexxii/InfluenceXXII.java  |  7 +-
 src/com/annimon/influencexxii/Stars.java      | 64 +++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100644 src/com/annimon/influencexxii/Stars.java

diff --git a/src/com/annimon/influencexxii/InfluenceXXII.java b/src/com/annimon/influencexxii/InfluenceXXII.java
index 5966a90..05c3c46 100644
--- a/src/com/annimon/influencexxii/InfluenceXXII.java
+++ b/src/com/annimon/influencexxii/InfluenceXXII.java
@@ -13,6 +13,8 @@ public class InfluenceXXII implements ApplicationListener {
     
     private Pointer pointer;
     private EnemiesController enemies;
+    private Stars stars;
+    
     private ShapeRenderer renderer;
     private BitmapFont font;
     private SpriteBatch spriteBatch;
@@ -41,8 +43,8 @@ public class InfluenceXXII implements ApplicationListener {
 		for (int i = 0; i < 5; i++) {
 		    enemies.addEnemy();
 		}
-		
 		pointer.setEnemiesController(enemies);
+		stars = new Stars(width, height);
 	}
 
 	@Override
@@ -60,6 +62,9 @@ public class InfluenceXXII implements ApplicationListener {
 		Gdx.gl.glClearColor(background.r, background.g, background.b, 1f);
 		Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
 		
+		// Draw stars
+		stars.draw(renderer);
+		
 		// Draw enemies
 		enemies.draw(spriteBatch, renderer);
 		
diff --git a/src/com/annimon/influencexxii/Stars.java b/src/com/annimon/influencexxii/Stars.java
new file mode 100644
index 0000000..7685b0b
--- /dev/null
+++ b/src/com/annimon/influencexxii/Stars.java
@@ -0,0 +1,64 @@
+package com.annimon.influencexxii;
+
+import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
+import com.badlogic.gdx.graphics.glutils.ShapeRenderer.ShapeType;
+import com.badlogic.gdx.math.MathUtils;
+import com.badlogic.gdx.math.Vector3;
+
+/**
+ * Stars background
+ * @author aNNiMON
+ */
+public class Stars {
+
+    private static final int MAX_STARS = 200;
+    
+    private float screenWidth, screenHeight;
+    private Vector3[] stars;
+    private float step;
+    
+    public Stars(float width, float height) {
+        this.screenWidth = width;
+        this.screenHeight = height;
+        stars = new Vector3[MAX_STARS];
+        for (int i = 0; i < MAX_STARS; i++) {
+            Vector3 v = new Vector3();
+            newStar(v, false);
+            stars[i] = v;
+        }
+        step = MathUtils.random(-20f, 20f);
+    }
+    
+    public void draw(ShapeRenderer renderer) {
+        renderer.begin(ShapeType.Filled);
+        final float w2 = screenWidth * 2;
+        for (int i = 0; i < MAX_STARS; i++) {
+            Vector3 v = stars[i];
+            v.z += step;
+            if (v.z <= -200) {
+                newStar(v, false);
+            } else if (v.z >= 2000) {
+                newStar(v, true);
+                v.z = MathUtils.random(-200, 100);
+            }
+            if ( (v.x <= -w2) || (v.x >= w2) ) {
+                v.x = -v.x;
+            }
+            // Color
+            float sx = screenWidth / 2 + v.x * 200 / (v.z + 200);
+            float sy = screenHeight / 2 + v.y * 200 / (v.z + 200);
+            float col = 1f - 1f * (v.z + 200) / 1500;
+            col = MathUtils.clamp(col, 0f, 1f);
+            renderer.setColor(col, col, col, 0.8f);
+            renderer.rect(sx, sy, 2f, 2f);
+        }
+        renderer.end();
+    }
+    
+    private void newStar(Vector3 v, boolean backward) {
+        v.x = MathUtils.random(-screenWidth * 2, screenWidth * 2);
+        v.y = MathUtils.random(-screenHeight * 2, screenHeight * 2);
+        if (backward) v.z = MathUtils.random(-200, 100);
+        else v.z = MathUtils.random(1900);
+    }
+}
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