From 740803e50c513aef7833ad684c207e4959fbb947 Mon Sep 17 00:00:00 2001
From: Lars Borm <larsborm@hotmail.com>
Date: Sat, 11 Aug 2018 22:02:56 +0200
Subject: [PATCH] Added moving background

The background now moves slowly as if the ship is flying forward. The image is rolled by moving the bottom rows of pixels to the top ever Nth frame.
---
 Spacey.py | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/Spacey.py b/Spacey.py
index 651f91b..4d5174e 100644
--- a/Spacey.py
+++ b/Spacey.py
@@ -3,6 +3,27 @@
 import numpy as np
 
 
+class Background_scroll(pygame.sprite.Sprite):
+    def __init__(self, background_image):
+        pygame.sprite.Sprite.__init__(self)
+        self.image = background_image
+        self.n_pixel_roll = 2 # Number of rows to roll from bottom to top
+        self.update_speed = 2 # Roll ever n frames
+
+        gameDisplay.blit(self.image, (0,0))
+
+    def update(self):
+        if frame_count % self.update_speed == 0:
+            # Convert surface to numpy array
+            imgarr = pygame.surfarray.array3d(self.image)
+            # Roll the image array
+            imgarr = np.roll(imgarr, self.n_pixel_roll, axis=1)
+            # Convert numpy array back to pygame surface
+            self.image  = pygame.pixelcopy.make_surface(imgarr)
+
+        gameDisplay.blit(self.image, (0,0))
+
+
 class Explosion(pygame.sprite.Sprite):
     def __init__(self, frames, xcoord, ycoord, scale=1.5, update_n=1):
         pygame.sprite.Sprite.__init__(self)  # call Sprite initializer
@@ -16,6 +37,7 @@ def __init__(self, frames, xcoord, ycoord, scale=1.5, update_n=1):
         self.update_n = update_n
         self.update_counter = self.update_n
 
+
     def update(self):
         self.update_counter -= 1
         if self.frame >= len(self.frames) - 1:
@@ -417,7 +439,7 @@ def main_menu():
                     quit()
 
         # Update main menu
-        gameDisplay.blit(background, (0, 0))
+        gameDisplay.blit(background_img, (0, 0))
         startbutton = gameDisplay.blit(start_button, (button_x_center, display_height * 0.4))
         creditbutton = gameDisplay.blit(credit_button, (button_x_center, display_height * 0.5))
         quitbutton = gameDisplay.blit(quit_button, (button_x_center, display_height * 0.6))
@@ -443,6 +465,11 @@ def credit_loop():
 
 def game_loop():
 
+    # Instantiate background
+    global background_img, frame_count
+    frame_count = 0
+    background = Background_scroll(background_img)
+
     # Instantiate Ship & Meteor and create a group for lasersprites
     global ship, ship_group, meteors, lasers, score_count, enemies, fps, timer, enemy_lasers, score_count
     global boss_bomb, explosions, explosions_boss
@@ -568,7 +595,7 @@ def game_loop():
                 continue
 
         # Update display and sprites
-        gameDisplay.blit(background, (0, 0))
+        background.update()    
         ship.update()
 
         if len(meteors) < 1 and enemies_meteors_spawning:
@@ -702,6 +729,10 @@ def game_loop():
         # Set FPS
         clock.tick(fps)
 
+        #frame counter
+        frame_count += 1
+
+
 
 # Here we initialize pygame, set variables and start the actual game
 pygame.init()
@@ -780,7 +811,7 @@ def game_loop():
 missile = spritesheetspace2.subsurface(pygame.Rect(1093, 711, 19, 40))
 boss_image = spritesheetspace2.subsurface(pygame.Rect(276, 0, 172, 151))
 controlscheme = pygame.image.load('Textures/controlscheme.png')
-background = pygame.image.load('Textures/space_background.png').convert()
+background_img = pygame.image.load('Textures/space_background.png').convert()
 credit_background = pygame.image.load('Textures/credits.png').convert()
 
 # Load files used in the game