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 Help for my enemy chase  (Read 2101 times) 0 Members and 1 Guest are viewing this topic.
Graziano Mesina

Senior Newbie

 « Posted 2006-09-26 22:52:50 »

Hi, I've an enemy that chase my player on maze tile game.
I've implemented the bresenham algorithm, it draw a rect from the enemy to the player, if this rect collides with a tile, enemy can't see the player and false is returned, otherwise it can see and true is returned.

The bresenham algorithm work fine, but I've a problem on my chase method:

px and py are player's coordinates
x and y are enemy's coordinates
validLocation return true if my enemy can walk in that direction:

 1  2  3  4  5  6  7  8  9  10  11  12  13 `private void chase(float px, float py)    {        if(x < px && validLocation(x + velocità,y))             EAST;        else if(x > px && validLocation(x - velocità,y))             WEST;        else if(y < py && validLocation(x,y + velocità))             SOUTH;        else if(y > py && validLocation(x,y - velocità))             NOTH;                  super.incremen();    }`

obviously this method isn't correct, for example, when I've this situation:

my ghost enemy goes to EAST, but when x > px ot goes to WEST

how I've to change the controls??

-Montanelli-: Ma lei evadeva quasi sempre, no? <br /><br />-Mesina-: Sì, ho la fortuna di avere i polsi più grossi delle mani...
Graziano Mesina

Senior Newbie

 « Reply #1 - Posted 2006-09-27 07:59:49 »

I was thinking to give a priority when I check (x < or > player X) & (y < or > playerY)

like this:

 1  2  3  4 `if(Math.abs(x-px) > Math.abs(y-py)than check (x < or > player X)elsecheck (y < or > playerY) `

but it's still imperfect
any ideas?

-Montanelli-: Ma lei evadeva quasi sempre, no? <br /><br />-Mesina-: Sì, ho la fortuna di avere i polsi più grossi delle mani...
dishmoth
 « Reply #2 - Posted 2006-09-27 09:49:56 »

I was thinking to give a priority when I check (x < or > player X) & (y < or > playerY)

like this:

 1  2  3  4 `if(Math.abs(x-px) > Math.abs(y-py)than check (x < or > player X)elsecheck (y < or > playerY) `

That looks pretty close to the correct answer to me, but I think you need to add some logic so that if abs(x-px) > abs(y-py) then the code first checks (x < or > px), and if it turns out that the enemy cannot move in that direction (east or west) then it falls back to checking (y < or > py) so that the enemy has the chance of moving north or south instead.  (And similarly if abs(x-px) <= abs(y-py).  First check for movement north/south, and if that isn't possible then check for movement east/west.)

As an aside, if you look at maze games like Pacman (which I'm assuming is similar to what you're doing), then the enemies are usually programmed so that once they have chosen which direction to move in, they keep moving in that direction until they reach an intersection in the maze.  (Also, they never stay still, and often they prefer to turn left or right rather than reverse their direction.)  This helps to give the impression that the enemies are behaving intelligently.

Simon

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