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[MrWiggles]

Reworking the catapults to fire with parabolic arcs - not to mention using the new impact code - feels like a real low hanging fruit at this point. Will any work be done to them?

I dont know if they're actually that low hanging. With the fabled army arc suppose to be introducing myriad of new siege tools, the work on catapults to include this may just be worthless time expenditure, when Sieges are overall redone. Toady stated what tentatively remains for this release, and also explictly stated that he wont be adding in more parabolic arcs to weapons, in particular to avoid the added dev time for working them in Adventure Mode weapons.

[NW_Kohaku]

There has to be a loss of energy as well from inertia, otherwise units would bounce around for ever. (actually; walls, etc. are 100% massive, so should cause a lot of momentum loss in collisions. translated into blunt trauma.) 

Technically, that depends on the elasticity of the collision. 

Hypothetically perfectly immovable objects like areas where all time has stopped, or say, walls in this game would have to hypothetically perfectly reflect all incoming force, as no force can be transferred into them.  They would be like a perfect mirror for all forces (and light).

It is then upon the carts to react to this reflection of force.  Provided they have the structural integrity to not crumple like a house of cards, they should actually just bounce backwards like a rubber ball, although they will probably toss unsecured cargo and lose plenty of energy to friction in the process.

[Cobbler89]

apart from the fact, that this is totally a suggestion and not a question which is not meant to be greened... using green instead of limegreen makes my eyes bleed!

Seconded, thirded, and fourthed. I've wanted to say this every time I saw the darker green text, and I did not because I felt that it's not in my place and that I'd be just a lone voice. I had to select the text to be able to read it.

Actually, thanks for pointing that out -- I hadn't noticed limegreen in the color list (or if I had, my brain probably ignored it because in most media lighter shades are the hard to read ones -- but then, that's usually not on a dark background, all of which didn't even consciously occur to me). Future reference, or should I go back and edit my questions for ease of reading?

As for suggestion vs. question... I'm a little unclear how half the things that get asked on this thread aren't borderline suggestion, although I guess a specific solution to a known problem could be taken to be more suggestive than most things; I guess I'll have to dig around the thread and learn better. 8^/ And maybe look into moving that quessuggesttion over to the suggestion forum if there hasn't already been talk there about the possible advantages of something in the raws similar to quality or decoration/encrusting (to be honest, the main reason I asked here was quite simply that I wondered if Toady had any plans for when/how he'd deal with it, having read a thousand comments about the elven problem but little to no reference to Toady's opinion of it; but maybe I'd find that if I kept digging).

[G-Flex]

Technically, that depends on the elasticity of the collision. 

Hypothetically perfectly immovable objects like areas where all time has stopped, or say, walls in this game would have to hypothetically perfectly reflect all incoming force, as no force can be transferred into them.  They would be like a perfect mirror for all forces (and light).

It is then upon the carts to react to this reflection of force.  Provided they have the structural integrity to not crumple like a house of cards, they should actually just bounce backwards like a rubber ball, although they will probably toss unsecured cargo and lose plenty of energy to friction in the process.

I don't see why walls have to be assumed to be perfectly, magically immobile. Sure, they don't move in-game, but it's not as if throwing a rock at a stone wall makes the wall move to any noticeable degree in real life either, even if the rock stops dead. This is a simulation; what matters are reasonable results, and a cart bouncing hilariously backward like a rubber ball off a cavern wall is not a reasonable result.

[NW_Kohaku]

I don't see why walls have to be assumed to be perfectly, magically immobile. Sure, they don't move in-game, but it's not as if throwing a rock at a stone wall makes the wall move to any noticeable degree in real life either, even if the rock stops dead. This is a simulation; what matters are reasonable results, and a cart bouncing hilariously backward like a rubber ball off a cavern wall is not a reasonable result.

It is all a matter of whether the impact should be elastic or not.

Real-life car with a steel chasis and plastic shell hits a solid reinforced concrete barrier?  Folds like an accordian because the steel can't hold up to the force of a one-ton vehicle decelerating at such incredible speeds.

Matchbox car made of some metal and plastic top hits a wall solid enough not to fracture or otherwise directly absorb much of the impact the way a plaster wall would?  Bounces off "hilariously like a rubber ball" because its internal structure is capable of withstanding the forces of the sudden changed direction of the forces at play.

Basically, physics says that either a high-speed cart has the structural integrity to bounce, or it should be smashed when it hits that wall.  (Barring the admission of walls taking structural damage.)

We already have the data for the forces required to fracture materials carts are made out of, so we can basically just test how much momentum a cart slams into a wall with to see if the material the cart is made of is capable of withstanding that much force. 

Of course, that would be involving the notion that carts can break.  If carts can't break, then physically, having them bounce off is the only thing even remotely physically reasonable is bouncing like a rubber ball.  Just plain stopping dead is even more physically impossible than merely bouncing.

[flabort]

Will we be able to hook animals to minecarts, and have them pull them along? Or have dwarves PULL (as opposed to push) minecarts at all?
It would be very useful for getting the carts up hills. Since mines often go down, down, into the ground, the uphill tracks to get stone and metal up hill would be hard to get a cart up without giving it energy from an outside source. I guess a dwarf pushing it works, but what if the dwarf tires out?
Will we be able to put any items in minecarts? Possibly including live animals?
Making a loop between the animal pen, the butcher, the tanner, and the leather workers, and putting a cart on those tracks would speed up the clothing industry fourfold. Any way to get more out of the industry would help.
Will we be able to make splits in the tracks, and send carts in different directions?
If in the above example, after the carts visited the butcher, half would go to the left, carrying any skins to the tanner, and the other half of the carts would go to the right, to the kitchens and food stocks. Both would eventually lead back to the start.

[G-Flex]

I don't see why walls have to be assumed to be perfectly, magically immobile. Sure, they don't move in-game, but it's not as if throwing a rock at a stone wall makes the wall move to any noticeable degree in real life either, even if the rock stops dead. This is a simulation; what matters are reasonable results, and a cart bouncing hilariously backward like a rubber ball off a cavern wall is not a reasonable result.

It is all a matter of whether the impact should be elastic or not.

Real-life car with a steel chasis and plastic shell hits a solid reinforced concrete barrier?  Folds like an accordian because the steel can't hold up to the force of a one-ton vehicle decelerating at such incredible speeds.

Matchbox car made of some metal and plastic top hits a wall solid enough not to fracture or otherwise directly absorb much of the impact the way a plaster wall would?  Bounces off "hilariously like a rubber ball" because its internal structure is capable of withstanding the forces of the sudden changed direction of the forces at play.

Basically, physics says that either a high-speed cart has the structural integrity to bounce, or it should be smashed when it hits that wall.  (Barring the admission of walls taking structural damage.)

We already have the data for the forces required to fracture materials carts are made out of, so we can basically just test how much momentum a cart slams into a wall with to see if the material the cart is made of is capable of withstanding that much force. 

Of course, that would be involving the notion that carts can break.  If carts can't break, then physically, having them bounce off is the only thing even remotely physically reasonable is bouncing like a rubber ball.  Just plain stopping dead is even more physically impossible than merely bouncing.

How elastic a collision is has to do with more than how much each object maintains its structure integrity, though; kinetic energy dissipates through other means. A bouncing ball loses energy on each bounce even if it isn't actually damaged.

Also, regardless of the elasticity of it, momentum can be transferred to the wall itself. This is obvious in the fact that if you toss something sticky (for example) at a wall, it stops dead even though  momentum needs to be conserved. The amount of momentum involved is usually just extremely small (from the wall's perspective) as to be unnoticeable.


In this case, the options aren't just "cart breaks" and "cart bounces off"; how well the cart bounces off relies on other factors.

[NW_Kohaku]

How elastic a collision is has to do with more than how much each object maintains its structure integrity, though; kinetic energy dissipates through other means. A bouncing ball loses energy on each bounce even if it isn't actually damaged.

Also, regardless of the elasticity of it, momentum can be transferred to the wall itself. This is obvious in the fact that if you toss something sticky (for example) at a wall, it stops dead even though  momentum needs to be conserved. The amount of momentum involved is usually just extremely small (from the wall's perspective) as to be unnoticeable.


In this case, the options aren't just "cart breaks" and "cart bounces off"; how well the cart bounces off relies on other factors.

In case you couldn't tell by now, G-Flex, the notion that walls in this game are "areas where time has completely stopped, and no energy can enter or leave" was a joke based upon the properties of the current game physics.  It's simply a reflection of how all energy must start and end in the cart unless it somehow flows outwards into the floor or heat energy or something else.

In the case of, say, throwing silly putty at a wall, it sticks because the material itself deforms quite readily.  Sticky things are really just highly viscous liquids that can deform and mold itself to the shape of its neighboring solids.  These are simply highly deformable substances that suffer no serious problems when they are deformed, unlike a cart, which needs structural rigidity.  That's still keeping the energy inside the projectile, and merely transforming its energy from whole-object kinetic energy into intra-object deformation.

Anyway, I'm not saying that loss of momentum should be completely negligible, but that if we have no deformity or significant friction loss, there is no Conservation of Energy justification for too much of the energy loss, and not modeling Conservation of Energy (as per those perpetual motion carts Toady had to nix) is much more breaking of the fundamental aspects of physics than a cart that bounces off more like a matchbox car than like a wad of silly putty.

That said, I still want to see friction heat capable of temporarily reducing the quality of cart wheels and leading to less efficient carts or brake failures or outright cart failures. 

[G-Flex]

In case you couldn't tell by now, G-Flex, the notion that walls in this game are "areas where time has completely stopped, and no energy can enter or leave" was a joke based upon the properties of the current game physics.  It's simply a reflection of how all energy must start and end in the cart unless it somehow flows outwards into the floor or heat energy or something else.

In the case of, say, throwing silly putty at a wall, it sticks because the material itself deforms quite readily.  Sticky things are really just highly viscous liquids that can deform and mold itself to the shape of its neighboring solids.  These are simply highly deformable substances that suffer no serious problems when they are deformed, unlike a cart, which needs structural rigidity.  That's still keeping the energy inside the projectile, and merely transforming its energy from whole-object kinetic energy into intra-object deformation.

You missed the point, actually. I was talking about momentum, which is always conserved, not kinetic energy, which sometimes is not. Also, things can hit another object and stick to it without deformation being necessarily involved. If I stick a heavy ball coated in velcro to a velcro-coated wall by throwing it at it, and it sticks, that's one example.

Anyway, I'm not saying that loss of momentum should be completely negligible, but that if we have no deformity or significant friction loss, there is no Conservation of Energy justification for too much of the energy loss, and not modeling Conservation of Energy (as per those perpetual motion carts Toady had to nix) is much more breaking of the fundamental aspects of physics than a cart that bounces off more like a matchbox car than like a wad of silly putty.

I'm not really sure what you mean here. The only aspect of "Friction loss" that wouldn't be appropriately modeled is whatever minor mechanical vibrations and heat would be generated, and those are often negligible even in the real world, and aren't simulated anywhere else in DF either (the engine doesn't care how much you heat up the ground when you land on it from a fall).

I'm just saying, it's perfectly valid simulation for a cart to hit a wall and bounce back with only a small portion of its original speed, without any kind of (significant or permanent) deformation or breakage being involved. This happens in the real world all the time, and anything being left out (like the conservation of momentum involved when something hits the ground/a wall, or heat due to friction/collision) is inconsequential anyway.

[Flaede]

Taking this in an antirely other direction:
Will dodging minecarts train dodging?

New addition to the danger room: a model train set!

[flabort]

You missed the point, actually. I was talking about momentum, which is always conserved, not kinetic energy, which sometimes is not. Also, things can hit another object and stick to it without deformation being necessarily involved. If I stick a heavy ball coated in velcro to a velcro-coated wall by throwing it at it, and it sticks, that's one example.

I would think that's the ball bouncing off, then the hooks catching on the loops, and the hooks and loops each bending and deforming, and pulling at the ball and wall. The hooks act as friction and deformation. IIRC. it deflects back to the wall, the hooks now deforming the other way when they hit the wall. It keeps going back and forth, faster than the eye can handle, until the energy is all dissipated elsewhere.

In other words, I think the velcro is deforming. Just... very little.

[Elone]

JEEEZ.

After the next version comes out, I will not build a cart for WEEKS while I instead use every other hauling improvement given.

The reason is all the minecart talk that I've seen in this thread so far, by now I've had enough of minecarts and minecart physics (which no one has seen yet but everyone knows everything about them) for the times to come.

Nothing personal, it's just the way I see it.

Regarding dwarves hauling multiple items in a bin/barrel, are we going to be able to set the distance which they will check, defining how 'nearby' is nearby? Can we set them to pick up an item, then only look in a 5 square radius for other items? Or 20 so that they check a fairly large area? Or 0 so that they would only get extra items from the same square? Or if not, how is 'nearby' defined?

[G-Flex]

I would think that's the ball bouncing off, then the hooks catching on the loops, and the hooks and loops each bending and deforming, and pulling at the ball and wall. The hooks act as friction and deformation. IIRC. it deflects back to the wall, the hooks now deforming the other way when they hit the wall. It keeps going back and forth, faster than the eye can handle, until the energy is all dissipated elsewhere.

In other words, I think the velcro is deforming. Just... very little.

The deformation isn't what actually matters, though. Yeah, there's generally going to be at least some deformation going on regardless of the example I use, but 1) that's not necessarily where the energy is going, 2) it's not a terribly necessary part of the process, and 3) momentum is always conserved anyway.

[Chthonic]

New addition to the danger room: a model train set!

Danger room?  Dining hall.

[h3lblad3]

New addition to the danger room: a model train set!

Danger room?  Dining hall.

Urist McDiner has eaten a masterful train recently.