Tweak mould rendering logic to have sane realtionship between image position and...

diff --git a/tabakrolletjie/enemies.py b/tabakrolletjie/enemies.py
index 7b26fed214ebb600a5366aa4d40c85b1eb6edcee..f668f1afe0f50fbf19a6655fd7a2bf3754af6816 100644 (file)
--- a/tabakrolletjie/enemies.py
+++ b/tabakrolletjie/enemies.py
@@ -31,6 +31,13 @@ class Mould(pymunk.Body):
         self._age = 0
         self._img = None
 
+    def pygame_pos(self, surface):
+        """Convert to pygame coordinates and offset position so
+           our position is the centre of the image."""
+        # The odd sign combination is because of the pymunk / pygame
+        # transform, but we do it this way to exploit Vec2d math magic
+        return pymunk.pygame_util.to_pygame(self.position + (-16, 16), surface)
+
     def get_image(self):
         if not self._img:
             name = random.choice(
@@ -88,11 +95,13 @@ class Mould(pymunk.Body):
 class Boyd(object):
 
     def __init__(self, gamestate, space):
-        seed = Mould(gamestate, space, (400, 400))
+        seed = Mould(gamestate, space, (350, 350))
         self._moulds = [seed]
         self._image = pygame.surface.Surface(SCREEN_SIZE)
         self._image.convert_alpha(pygame.display.get_surface())
         self._image.fill((0, 0, 0, 0))
+        self._image.blit(seed.get_image(),
+            seed.pygame_pos(self._image), None, pgl.BLEND_RGBA_ADD)
 
     def tick(self, gamestate, space):
         redraw = False
@@ -102,9 +111,8 @@ class Boyd(object):
         if redraw:
             self._image.fill((0, 0, 0, 0))
             for mould in self._moulds:
-                pos = pymunk.pygame_util.to_pygame(mould.position, self._image)
-                self._image.blit(mould.get_image(), pos, None,
-                                 pgl.BLEND_RGBA_ADD)
+                self._image.blit(mould.get_image(),
+                    mould.pygame_pos(self._image), None, pgl.BLEND_RGBA_ADD)
 
     def render(self, surface):
         """Draw ourselves"""