I think it would be easier to understand this if instead of assigning
the direction as an arbitrary number, you instead had separate x and y
directions, which could each have only the values -1, 0, or 1.
A naive directional algorithm (which assumes no obstacles between the
monster and the ninja) could be something like:
monster.x_dir = cmp(ninja.x, monster.x)
monster.y_dir = cmp(ninja.y, monster.y)
That avoids all of the if/elif messiness entirely, and would probably
simplify the update logic that actually moves the monster sprite as
well. Also rather than using the rect x and y, which ties the
algorithm to the vagaries of where the sprites are drawn, the x/y
values above could be tile coordinates. This means it would work
correctly even if you change the orientation of the tiles (e.g., use
an isometric layout).
FWIW, I think the bug might be fixed by changing the second 'if' to an
'elif', but I think it would be more worthwhile to simplify/abstract
out the approach.
hth,
-Casey
On Apr 27, 2007, at 9:53 AM, Samuel Mankins wrote:
I'm working on a sort of RPG/Roguelike game, and right now I'm have
problems with the monster's AI. It works just fine if the Ninja (The
player) is above, below, or to the left of the monster, but if it's
tot he right, the monster just goes up or down, but not right. Here's
the directional code, are there any problems people can see? (For the
monster's direction, 1 = right, 2 = up, 3 = left, and 4 = down)
if self.ninja.rect.x < monster.rect.x and monster.rect.x -
self.ninja.rect.x > monster.rect.y - self.ninja.rect.y:
monster.direction = 1
elif self.ninja.rect.x > monster.rect.x and monster.rect.x -
self.ninja.rect.x > monster.rect.y - self.ninja.rect.y:
monster.direction = 3
if self.ninja.rect.y < monster.rect.y and monster.rect.y -
self.ninja.rect.y > monster.rect.x - self.ninja.rect.x:
monster.direction = 2
elif self.ninja.rect.y > monster.rect.y and monster.rect.y -
self.ninja.rect.y > monster.rect.x - self.ninja.rect.x:
monster.direction = 4
elif self.ninja.rect.y < monster.rect.y and monster.rect.x ==
self.ninja.rect.x:
monster.direction = 2
elif self.ninja.rect.y > monster.rect.y and monster.rect.x ==
self.ninja.rect.x:
monster.direction = 4
elif self.ninja.rect.x < monster.rect.x and self.ninja.rect.y
== monster.rect.y:
monster.direction = 1
elif self.ninja.rect.x > monster.rect.x and self.ninja.rect.y
== monster.rect.y:
monster.direction = 3
If you can't see anything, thanks anyway!