User:AaronR/Arbitrary direction melee surfing

I mentioned on my talk page a movement idea I was thinking up. I was trying to come up with various ways of doing bullet dodging in melee, and this was the only idea I could think of that would make any sense. The problem is, I don't know if it's been done before. (I hardly pay any attention to melee.)

First of all, this method wouldn't be used at all unless there were about 5 or less bots on the battlefield--as ABC has said, melee bullet dodging is useless if you dodge yourself into the center of the battlefield and there's 9 bots firing at you.

That said, the idea works like this. First, the bot tries its best to scan all the enemies and see if they fired a wave in the last couple ticks. It tracks all the waves on the battlefield at once.

Then, rather than picking a large number of points to consider like in Minimum Risk Movement, the bot picks a small number of directions--possibly fixed directions, in which case you'd get something like Tron.

The bot then precise predicts how far it could move in each direction before any wave hits it. This gives it a point for each direction, as well as the wave that would hit the bot if it moved in that direction. The movement then calculates the GuessFactor danger in the normal way (using separate data for each opponent, of course). In a practical implementation, this danger would be summed with a typical Minimum Risk Movement point danger factor.

Finally, the bot would move by directions rather than goto. It would constantly recalculate the direction to move in, relying on a "don't stay in one place" heuristic to get it moving.

So, has something really similar been implemented before? I see something kind of like this on Talk:Melee Strategy from the old wiki, but it isn't this specific. Gameplay-wise, do you think it would actually work better than plain-old MR movement?

P.S. One more idea that I have is a way to fix the "assume everyone is firing at you" problem with the implementation I just described--since most bots target the closest opponent, throw out any waves that pass "x" number of other bots before you.

« AaronR « Talk « 08:23, 2 October 2009 (UTC)

To my knowledge I don't think any robots have implemented this yet. Unless you count what I have been developing for a while now. One point that I think differently that you, is the decision on which direction to move. I think of choosing the point exactly same as Minimum Risk Movement, then predict each point, simulate the wave, and add the danger for any waves hit/passed between you and your target point. With some risk at center of the battlefield, I think you can use this as main melee movement. About directional-base versus goto, many MR-robot changes its destination point on-the-fly, they won't actually reached the destination (except HawkOnFire). But this method could be awfully slow, since it involve at least a hundred precise predictions per tick.

To your PS, many melee top bots, which you will want to dodge better, doesn't choose target at all =) --Nat Pavasant 08:51, 2 October 2009 (UTC)

When I was thinking about this algorithm, I was explicitly trying to design it to be as fast as possible. That's why it only picks a small number of directions instead of a large number of points, and stops as soon as a single wave hits. Your idea would probably actually work better, though, because it would account for multiple waves. Also, I know that most MR movement bots don't reach their destination every time, but I wanted to emphasize that my design works almost entirely with directions instead of points.

As for the "top bots don't choose a target" bit--top bots may not choose a target explicitly, but the effect is somewhat similar. For example, last I heard Shadow's gun weights possible target angles on inverse distance. With your multiple-waves method, you could effect this in reverse by weighting predicted waves on inverse travel distance or inverse travel time. Then you wouldn't have to throw out any waves, but it might be crazy slow. « AaronR « Talk « 11:27, 2 October 2009 (UTC)

Garm does something like this. It has 4 differen movement directions (0,90,18, and 270 degree), yes like tron... It predicts its movement for about 20 ticks in each of this directions. You shuld be able to see this in garms debug graphics (take a version which was entered in melee rumble: Garm 0.9u). But it was more of an extension to the 1on1 Surfing and is horrible slow. Using a differend movement for the first half of a battle would surely increase speed and score... Old versions surf every wave, weighted on distance. The newest one only close waves. I focused on the 1on1 part during my movement code cleanup, i removed some bugs and changed some elementary things. Therefor the melee part technically works, but it needs some new tuning.

If you are intrested we could start a teamwork, we could start with Garm as a basis and extend or replace its current melee movement. Garms design is quite modular and supports melee wave detection, scancode etc. I havent looked at the (melee) gun for some while, but it should be ok for now. What do you think? --Krabb 13:03, 2 October 2009 (UTC)

Nice thoughts here. I know a couple people have some Melee bullet dodging in the works, but I'm not sure how similar their implementations are. My (unreleased) attempts at a Twin Duel surfer work a lot like you say here: precise prediction in 8 directions until a wave intercepts, like a variant of True Surfing. If we ever add a MegaBot division of Twin Duel, I think you could do some very effective Twin Surfing with something along these lines. --Voidious 14:01, 2 October 2009 (UTC)