Added translucency.

robotgame/worldobject.py

@@ -24,6 +24,10 @@
 A generic world object.
 """
 
+import pygame
+import numpy
+import copy
+
 class WorldObject(object):
     def __init__(self, level, x, y, z=0, direction=(1, 0), speed=5,
                  tile_x=64, tile_y=48,
@@ -36,6 +40,9 @@ class WorldObject(object):
         self.holding = None
         self.holder = None
 
+        if hasattr(self, 'img'):
+            self.img = copy.copy(self.img)
+
     def set_init_pos(self):
         self.init_x, self.init_y = self.x, self.y
 
@@ -69,6 +76,17 @@ class WorldObject(object):
     def use(self):
         pass
 
+    def set_alpha(self, value):
+        """
+        Set the relative translucency of the per-pixel-alpha image.
+
+        Value between 0 - 1, where 0 is completely transparent and 1 is
+        completely opaque.
+        """
+        if hasattr(self, 'img') and hasattr(self, 'orig_alpha'):
+            alpha = pygame.surfarray.pixels_alpha(self.img)
+            alpha[:] = (self.orig_alpha * value).astype(numpy.uint8)
+
     def update(self, e, t, dt):
         if self.x > self.move_x:
             self.x -= min(self.speed * dt * self.tile_x,