sports game -need AI

[Christina]

er.. hi
this is my first post.

I'm making a remake of Ballistix, an old game by Psygnosis.
You control a pointer that shoots ammo towards a ball. The purpose is to score a goal against a slightly tilted game board.

Here's the file
http://www.filefactory.com/file/edbd2d/

I was wondering if anyone has any ideas/links/logical diagrams for a suitable AI; an enemy pointer that shoots ammo trying to score a goal as well. I'm guessing top-down soccer AI would be a good start.

thank you in advance.
christina

P.S. let me know if this game is crap.

[DavidN]

It's an interesting idea - I think it could benefit from using a movement extension, as you really need to be able to shoot in more than 32 directions. Having the trigger and the movement on different controllers felt awkward - I would move the fire button to the left mouse button.

As for AI, I'm really not sure... the Pathfinder object may help, as you would need to be able to find the shortest reasonable path to the top of the level. The difficulty is getting the enemy pointer to be able to shoot the ball to try and follow this path.

[Christina]

ah yes I forgot.
cursor keys -movement
space - trigger

I will definitely include a redefine option, plus mouse control, thanks a lot!

I'm not sure I want more than the 8 directions I've currently set it to shoot towards (original game). I'm afraid it will subtract from the predictability. I'll give it a shot though, thanks! I've already worked out the trigonometry for 32 directions, so it should be a breeze.

I think the enemy pointer doesn't need to get to the bottom of the level. Instead it needs to move in a way that will give it lots of lines of sight towards the player's goalpost at the bottom. hmmm

anyhow thanks a lot!

[Christina]

any more ideas?

[AllistairF]

The only thing I can say about AI is that you have to understand the sport and you have to think like the computer, in terms of cause and effect, or stimulus and action.

[vortex2]

The common approach to doing this would be to model each player as a Finite State Machine (FSM).

Each player would have their current state, and rules to transition from their current state to other states.

A better explaination can be found at AI Junkie

[Christina]

thanks alistairF and thanks a million vortex2, for the link!
It's exactly what I wanted.

here's my effort at AI before reading about FSM:

http://www.filefactory.com/file/ddccd5/

kisses,
christina

[Christina]

ok I need help!

Assuming the enemy arrow has
1.a targeting phase
2. a shooting phase

I want my targeting phase to be like this:

A test object ("Scout") that revolves around the ball like a satellite, with a radius of R. This object tests all positions around the ball for perfect linear alignment of: the "Scout", the "Ball" and the "Goalpost". Essentially it attempts to find the perfect line of sight from the Scout to the Goalpost, including the Ball.

I was thinking I could do it with 1-pixel ActiveObjects ("Particle") shot from the Scout towards the Ball. Everytime a "Particle" collides with the Goalpost, the X/Y coordinates of the position where it was shot from, are stored as a desirable position, and the Enemy Arrow attempts to go near it.

Also, the Scout will try other radii around the ball (R plus/minus 100 pixels), effectively testing all (or most) points around the Ball.

Is there any way MMF2 can check all of these points using only math? Is there any other line-of-sight algorithm I can use, without having to rely on shooting particles?

I'd appreciate an example, or a link to an article..

kisses

[vortex2]

Say you had two points P (Your player) and G (your goal post).

You want to find in between values from P to G.

To do that you can do : I.X=P.X+(G.X-P.*(Step/100.0) I.Y=P.Y+(G.Y-P.Y)*(Step/100.0) where step ranges from 0-100.

If you then set an object to I.X and I.Y and adjust the step between the 0-100 range you can get points between P and G :P. By then testing collisions for this object, you can tell if you have a clear line between P and G. If you get a collision then you know you have an obstacle in the way and it is not a clear line of sight.

[Christina]

vortex2 so this is essentially the same as shooting a DetectorParticle, only it doesn't have to pass from each and every point in its trajectory, because I can control the step. Do I get it right?

It's a splendid idea! Let's see how it goes.

Thanks!