Scratch

As Llama points out, this can be tricky.  You have to program that part yourself, using rules for what the "computer" should do in different situations.  The easy approach is to have the enemy just point toward the "player" and move, but this can get old pretty quickly.

I have a jet fighter game: http://scratch.mit.edu/projects/EdnaC/33613 that lets you choose "one player" mode in which you are up against the computer (sometimes called the "AI", for Artificial Intelligence).  A good bit of work was required to get the AI to appear to be "intelligent".   There is some additional discussion (and a description of the rules that define the AI in "StealthFighter") in this thread:

http://scratch.mit.edu/forums/viewtopic.php?pid=14956#p14956

-MrEd

A.I. is one of the toughest problems in software, and it varies quite a bit depending upon the project, as Mayhem suggests. Ednac's project is a good example. The best way to start is to turn off your computer, sit in a dimly lit room, and just concentrate on what you would expect a non-perfect player would do, then write it out on a blank sheet of paper in a messy fashion using words, arrows, etc. as high level concepts. THEN, when you've thought about it enough, convert your thoughts into computer code to implement the general idea. For example, in the case of pong, the general idea would be something like "move smoothly from current position to where the ball is going to intersect at some set speed that depends on the level, with a random mistake built into the y-coordinate, which also depends on the level."

In the case of a racing game that is top-down view, the general idea might be "make the car go around the track at an average speed that increases with level, such that it mistakenly hits the edges of the track from time to time, less often at higher levels." To implement this idea you could place a bunch of invisible (ghost = 100) sprites along the track that act as "waypoints" such that the car simply tries to connect the dots (more waypoints near the corners, just a couple on the straightaway.)  Each waypoint could invisibly move around its ideal (perfectly centered) position at a distance that decreases with level. If you want the computer car to occasionally bump into the player, you could make the waypoints ahead of the computer car move toward the player's car and adjust the speed slower or faster, depending.

Last edited by chalkmarrow (2008-02-05 13:29:22)

Read thru the second paragraph of Chalkmarrow's suggestion.  The idea is to use "random" (it's in the "numbers" blocks) when placing the waypoints.  Instead of having the waypoints go to fixed positions, you modify the position by adding a random number.

In Waypoint1

When (green flag or setup broadcast)
Go to x: 125 + Random (-10 to 10) Y: 90 + Random (-10 to 10)
Hide

This would give you a hidden sprite somewhere between

X 115 to 135 , Y 80 to 100

The range that random picks a number from can be tailored, say if at that waypoint, going less than 125 could make the car hit a wall, you could use "Random (0 to 20)".

-MrEd

Thanks for your help, I will try it out. Cheers again.

Freddie-few: That would definitely work.  Good idea. You could keep the red shell hidden until the player touches the box, then you could make it go to the location of the player until he shoots, then you could make it act like the AI until it makes a full circuit. The trick is making sure that the shell knows which waypoint to go to first. I haven't thought about how to do that, but I'm sure you could figure it out...

Ok - I've been trying for that last hour or two on the exact same thing. I can create the sprite, hide it and then show it when the computer kart touches the box, but then it just stays in the same place. I'll keep trying but just wondering if anyone has any useful tips. It should be quite easy to make the controls for the player kart.

Much appreciated.