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Author Topic:   Tanks
LDA
Administrator
posted June 04, 2001 03:08 PM            
I'll make a few comments about tank design to help clarify a few points in the discussions about tanks.

Except for the Mite <novelty tank> the tank stats were kept the same to help keep racing fair. Of course this doesn't apply much now that TM is becoming more focussed on deathmatch.

Mass determines how much the environment effects the tank...splash push....and is the key difference between liquid and steel tanks.

Top speed is not a fixed limit....It can be exceeded going down hill.

Add acceleration if your tank is too slow on hills or you are setting gravity higher... <larger negative number> to try for that WWII tank combat effect.

Armor is simply armor/hit points but with a damage gradient from front <strongest> to rear <weakest>.

Now that's pretty sketchy, so I'll comment on what creates the subtle differences that you observe.


All other stats being the same, it's the tank shape that counts.

On the bottom of each tank is a series of contact points. A contact points has to be touching the ground to drive the tank forward or turn....etc.

As for damage, the front can take the most damage and rear the least. There is a gradient around the tank. Given there more nebulous shape, a liquid tank might be taking a side hit when it appears to be taking a frontal hit.

When a tank takes splash/push it is temporarily disabled <out of control>, having lost most of its contact with the ground. And as you experienced players know, the key to the dirtball attack is bouncing the opponent in the air <out of control> That's why the dirtball was designed to just be reloading as the opponent is landing and regaining control...<tension and skill>

Control is the key <You can't drive, turn of fire with much effect if your tank is flopping around like a fish on a dock.> As soon as contact points touch down you can start regaining control, and that's where shape plays a major part.

The other major influence which is always changing and has a huge effect on tank performance is the terrain itself. As the terrain shape and roughness effects the ability of those contact points to be on the ground < to accelerate and turn the tank>, (and as no game has changeable terrain like Tread Marks) <gratuitous plug> ....the terain creates a constantly changing set of parameters for the player to factor into decisions.

Jim

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JVortex
Member
posted June 04, 2001 06:28 PM            
well thanks for that clairification jim. one thing tho; i assume that turrets behave in the same way as far as damage and so on go?

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LDA
Administrator
posted June 04, 2001 07:30 PM            
Yes, the turret is just calculated as part of the tank.

Jim

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The Weatherman
Member
posted June 04, 2001 08:17 PM         
So, the back of the turret is the back of the tank, no? Then my shooting test must have been really flawed... I saw that a main gun to the back fo a steel did 30 pts damage vs 40 pts to the platypus (both having an armor of 1 and using the same type of tank to shoot and be shot). My numbers for the front were 15 and 20 respectively. Is there no other variable that would account for this apparent difference in armor? Maybe a differece in the strength of the gun? Mass? Even just from game play I notice that the platy has weaker armor. Any thoughts?
Thanks.

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peeeto
Member
posted June 05, 2001 01:10 AM         
hmm... so contact with the ground isn't calculated with a simple bounding box? or are the "contact points" the corners, edges & sides of the bounding box?

that's interesting, as the "Skimmer" tank that RexR and i worked on was raised off of the ground by adding a small poly about 1 meter beneath the tank. i simply mapped the UV coord's off of the texture bitmap so that the poly became invisible. has anyone noticed the the skimmer is less maneuverable than other tanks?

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Karldar
Member
posted June 05, 2001 01:33 AM            
Yeah, I noticed that, peeeto. Actually, that's the main reason I don't use that tank that much . It seemed to me that it should turn much faster than it does. On the other hand, Voyager is really quick, but it seems to be raised off the ground too. Wonder how JV did that...hmmm *envisions thought bubble of an old mad scientist laboratory*

------------------
I like pie!

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LDA
Administrator
posted June 05, 2001 04:11 AM            
....contact points on the underside of a fairly simple bounding box.

The uneven terrain throws things off, as it is hard to get a odd shaped designs to maintain good ground contact.

Jim

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peeeto
Member
posted June 05, 2001 08:04 AM         
thanks for the input, jim. i remember past discussions about how collisions & contact are based in bounding boxes.

but i'm still not entirely clear (i tend to read too much into what people say, making it more complicated than it really is)...

when you say "fairly simple bounding box", do you mean
1) "simply one bounding box", as determined by the geometry of the tank body & turret?
or
2) a simple bounding shape made up of two bounding boxes: one for the body, and one for the turret?
or
3) some other type of fairly simple bounding envelope that may not actually be box-shaped?

again, sorry if i'm making this more complicated than it is - i just want to be entirely clear.

...if the bounding shape(s) is/are true box(es), the Skimmer should actually be one of the most stable & maneuverable tanks. it's length/width ratio is only slightly greater than 1.0 (i think i remember you saying that the "best" shape is length/width ~1).

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JVortex
Member
posted June 05, 2001 01:31 PM            
i agree w/ peeeto on that note of clarification. ive been tinkering w/ different shaped tanks and different center of gravity points and have noticed some dramatic differences, but i still dont completely understand what it is that im exactly doing to make these differences.

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coax
Administrator
posted June 06, 2001 02:24 PM            
lol, i was wrong. I thought you would never figure it out untill LDA told you apparently even when they do tell you. You guys still can't figure it out. Not like bounding boxes make any sence to me though, I'll leave the modding to you guys.

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LDA
Administrator
posted June 06, 2001 08:44 PM            
Unfortunately the master (Seumas) isn't here to clarify the issue...

...and I don't think that Tom has had a chance to really dig into that area of the code yet....so more info will come out eventually.

As I understand it the Turret just extends the box upward and the gun object is ignored.

Jim

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JVortex
Member
posted June 07, 2001 01:31 AM            
oh, ok, gotcha...

thanks Jim

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