Re: [pygame] AI bug

[Casey Duncan <casey@xxxxxxxxxxx>]

Actually if you use tile coordinates you shouldn't need to detect  
this ahead of time. Typically an "attack" is the same command as a  
move except that the destination square is occupied. So, you can just  
make it so that when the monster attempts to move into the ninja's  
square, it attacks the ninja. If the ninja survives, the monster  
stays in the starting square, but if he (or she ;^) dies then the  
monster might move into the now dead ninja's square to do a little  
victory dance or something 8^)

-Casey

On Apr 28, 2007, at 2:27 PM, Samuel Mankins wrote:

> Thanks, this works great!
> They do have a little trouble with obstacles, but I think I can fix  
> that. What I want to do now is detect when the Ninja is within a  
> block size of the monster, so it can stop and attack... Any ideas?
> Thanks!
>
> Casey Duncan wrote:
> > 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!