feat(examples): add parallax

https://www.reddit.com/r/RenPy/comments/1br72fr/ingame_parallax_like_in_slay_the_princess/

Author: remarkablemark

game/examples/parallax.rpy

@@ -0,0 +1,75 @@
+# https://www.reddit.com/r/RenPy/comments/1br72fr/ingame_parallax_like_in_slay_the_princess/
+
+init python:
+    class MouseParallax(renpy.Displayable):
+        def __init__(self, layer_info):
+            super(renpy.Displayable, self).__init__()
+            self.xoffset,self.yoffset = 0.0, 0.0
+            self.sort_layer = sorted(layer_info, reverse=True)
+            cflayer = []
+            masteryet = False
+            for m, n in self.sort_layer:
+                if (not masteryet) and (m < 41):
+                    cflayer.append("master")
+                    masteryet = True
+                cflayer.append(n)
+            if not masteryet:
+                cflayer.append("master")
+            cflayer.extend(["transient", "screens", "overlay"])
+            config.layers = cflayer
+            config.overlay_functions.append(self.overlay)
+
+        def render(self, width, height, st, at):
+            return renpy.Render(width, height)
+
+        def parallax(self, m):
+            func = renpy.curry(trans)(disp=self, m=m)
+            return Transform(function=func)
+
+        def overlay(self):
+            ui.add(self)
+            for m, n in self.sort_layer:
+                renpy.layer_at_list([self.parallax(m)], n)
+
+        def event(self, ev, x, y, st):
+            import pygame
+            if persistent.parallax_on:
+                if ev.type == pygame.MOUSEMOTION:
+                    self.xoffset, self.yoffset = ((float)(x) / (config.screen_width)) - 0.5, ((float)(y) / (config.screen_height)) - 0.5
+
+    def trans(d, st, at, disp=None, m=None):
+        d.xoffset, d.yoffset = int(round(m * disp.xoffset)), int(round(m * disp.yoffset))
+        return 0
+
+label parallax:
+
+    scene black
+
+    init python:
+        MouseParallax([
+            (40, "farback"),
+            (20, "01"),
+            (0, "02"),
+            (-20, "03"),
+            (-40, "04"),
+            (-60, "05"),
+            (-80, "06"),
+            (-100, "07"),
+            (-120, "08"),
+            (-140, "09"),
+        ])
+
+    scene bg sky onlayer farback at Position(ypos = 1080)
+    show 01 forest onlayer 01 at Position(ypos = 1200)
+    show 02 forest onlayer 02 at Position(ypos = 1140)
+    show 03 forest onlayer 03 at Position(ypos = 1120)
+    show 04 forest onlayer 04 at Position(ypos = 1080)
+    show 05 particles onlayer 05 at Position(ypos = 1200)
+    show 06 forest onlayer 06 at Position(ypos = 1140)
+    show 07 particles onlayer 07 at Position(ypos = 1120)
+    show 08 bushes onlayer 08 at Position(ypos = 1080)
+    show 09 mist onlayer 09 at Position(ypos = 1200)
+
+    pause
+
+    return

game/examples/start.rpy

@@ -33,6 +33,9 @@ label start:
         "Map":
             jump map
 
+        "Parallax":
+            jump parallax
+
         "Python":
             jump python_example