Merge pull request #19 from musabkilic/master

Added this.size to bird.js and improved the code for keeping the bird in the screen

Author: shiffman

bird.js

@@ -7,9 +7,12 @@ class Bird {
   constructor() {
     this.y = height/2;
     this.x = 64;
+    this.size = 32;
+    
     this.gravity = 0.6;
     this.lift = -15;
     this.velocity = 0;
+    
     this.icon = loadImage("graphics/train.png");
     this.width = 64;
     this.height = 64;
@@ -29,13 +32,13 @@ class Bird {
     this.velocity *= 0.9;
     this.y += this.velocity;
 
-    if (this.y >= height) {
-      this.y = height;
+    if (this.y >= height - this.size/2) {
+      this.y = height - this.size/2;
       this.velocity = 0;
     }
 
-    if (this.y < 0) {
-      this.y = 0;
+    if (this.y <= this.size/2) {
+      this.y = this.size/2;
       this.velocity = 0;
     }
   }