Guest Big Time Software Posted May 20, 1999 Share Posted May 20, 1999 Lokesa's post pretty much says it all... Steve Link to comment Share on other sites More sharing options...
Thomm Posted May 21, 1999 Share Posted May 21, 1999 Hi again ! Okay, one last round before I go to sleep ! 1) My 2.5D statement and my column analogon were based on your emphasis on a 3D world. So, if I would use a tile system and I want to add a 3rd dimension I would interpret a wood tile as a 2 m times 2 m times e.g. 10 m prism. Thus I would know that this 2 x 2 area is covered with 10 m high trees. That means that I could look over the tile only if I climbed a very high hill. This is how I understand 3D LOS in combination with a tile system. 2) About the difference between "best" and "100 % realistic" you are right and I was wrong. From now on I will think of it as "the best LOS algorithm of a tile based strategy game of CMs scale". (Do we agree ?) 3) Quote: "Do not forget that CC is at a whole scale lower than Combat Mission". I have understood this and I think that I have mentioned it myself. 4) Quote: "CC is flat, 2D" Well aren't there elevation levels in CC ?! Can't you shoot over a two-storey building from a three storey building ? I would call this 3D LOS calculation ! What am I misunderstanding here ? I know about the flaws that Lokesa pointed out and I agree that Atomic was careless with the data and the implementation of their algorithm. I just want to make sure that I understand correctly how it is supposed to work. I would be shocked to learn that CC does not use the 3D LOS technique I thought it does, though buggy ! Of course you will not face problems like non-existing hills because of the 3D visualization of your terrain. To Moon: Your reply was very clear and understandable ! You made your (=BTS') point very well ! Thanks to everybody, maybe you will even write me more despite of the little misunderstandings we seem to have, though I think we are converging quite well ... Regards, Thomm P.S.: Do you use the A* algorithm as a pathfinder ? Link to comment Share on other sites More sharing options...
Guest Big Time Software Posted May 21, 1999 Share Posted May 21, 1999 <BLOCKQUOTE>quote:</font><HR>Hi again ! Okay, one last round before I go to sleep !<HR></BLOCKQUOTE> Ah, I remember when I had time for sleep <BLOCKQUOTE>quote:</font><HR>So, if I would use a tile system and I want to add a 3rd dimension I would interpret a wood tile as a 2 m times 2 m times e.g. 10 m prism. Thus I would know that this 2 x 2 area is covered with 10 m high trees. That means that I could look over the tile only if I climbed a very high hill. This is how I understand 3D LOS in combination with a tile system. <HR></BLOCKQUOTE> Now I see what you mean. The way you describe it is basically the way it works. A subtile with woods on it would, for example, be something like 2Lx2Wx10H. The calculations know about every single subtile's dimensions and calculate correctly for all of them in relation with each other. <BLOCKQUOTE>quote:</font><HR>About the difference between "best" and "100 % realistic" you are right and I was wrong. From now on I will think of it as "the best LOS algorithm of a tile based strategy game of CMs scale". (Do we agree ?)<HR></BLOCKQUOTE> Nope No matter what you think, we know that what we have is the best LOS algorithm of ANY commercially available (we have no idea what government military sims do!) wargame ever made, at any scale. You should understand that we don't boast about things that aren't true. We are very careful to not make claims that we can not back up. In this case we stand behind the data. Once you see CM for yourself we challenge you to find any game that can come even close to what we have. The only game you have brought up so far has been debunked as horribly flawed. <BLOCKQUOTE>quote:</font><HR>Quote: "CC is flat, 2D" Well aren't there elevation levels in CC ?! Can't you shoot over a two-storey building from a three storey building ? I would call this 3D LOS calculation ! What am I misunderstanding here ?<HR></BLOCKQUOTE> You simply can not do a true 3D LOS without a true 3D environment. CC uses the same system that old boardgames do. Each piece of terrain has a height attribute. These are used in a 2D way to simulate a 3D system. Basically, the LOS line draws from tile to tile. If the number of the next tile is, for example, greater than the tile before, LOS is blocked right there and then. Very crude, very imprecise, and very 2D. And as you see from various posts in this thread, and elsewhere, CC doesn't even get that right. A good example of how CM's system translates into more realistic 3D simulation is a simple Woods tile. Within that tile there can be any number of different heights, including a straight cliff of 80m. So while the tile is a tile, it can also be 20% 80m high, 60% 0m high, and 20% -20m high. The LOS system knows all of this and what that means in terms of being able to see from point A to B. In CC this would not be possible. [feature previously mentioned here deleted because Charles tells me it juuuust might not get into the first release <g>] <BLOCKQUOTE>quote:</font><HR>Of course you will not face problems like non-existing hills because of the 3D visualization of your terrain.<HR></BLOCKQUOTE> Exactly. This is the difference between a 2D approximation of 3D and a true representation of 3D. Our maps and data are built from the same thing. No chance of an error. <BLOCKQUOTE>quote:</font><HR>Thanks to everybody, maybe you will even write me more despite of the little misunderstandings we seem to have, though I think we are converging quite well ... <HR></BLOCKQUOTE> I think everything will become much clearer when you see Combat Mission for yourself. Until you have played it there is no really good way to explain the differences. Like I have said before, I have played pretty much every wargame out there AND Combat Mission, so I am in a very good position to be able to know what I am talking about. Since CM is the first 3D wargame ever, it is understandable that some of these concepts are a bit hard to understand. <BLOCKQUOTE>quote:</font><HR>Do you use the A* algorithm as a pathfinder ? <HR></BLOCKQUOTE> I'm not sure what you mean here. Steve [This message has been edited by Big Time Software (edited 05-20-99).] Link to comment Share on other sites More sharing options...
Marko Posted May 21, 1999 Share Posted May 21, 1999 Wow, this thread has ballooned! The A* algorithm is a pathfinding algorithm for units on a grid. It attempts to find the shortest path between two arbitrary points on such a grid. By shortest path, I mean that path which incurs the lowest movement cost, given that each element of the grid will in general have a different movement cost. There are more precise methods (which are slower) and more rudimentary methods (which are faster). I have a feeling that Charles (programmer guy at BTS) is grappling with this issue as we speak, because pathfinding is likely to be a big issue for the planning AI, which is still unfinished at this stage (correct me if I'm wrong). I find it amazing that we can speak of such things here on this forum. I've never heard of another company allowing the same (somewhat technical) public dialogue. Marko Health Warning: The above is the writings of an amateur, a dilettante! Treat with caution! Link to comment Share on other sites More sharing options...
Guest Big Time Software Posted May 21, 1999 Share Posted May 21, 1999 Yeah, I thought that's what it was. But since I'm not the programming geek I had to ask Charles (who is the programming geek <g>). He said that it he will not likely use this system as it is too simplistic. Beyond that all I can say is that pathfinding is nothing new to Charles. But yes, it tends to be a real CPU hog. Steve Link to comment Share on other sites More sharing options...
Thomm Posted May 21, 1999 Share Posted May 21, 1999 Hi Thomm, Yup, looks like you are just about ready to go back to your work Few minor corrections and I think this thread will indeed have run its course: <BLOCKQUOTE>quote:</font><HR> You use a grid of points to describe the terrain elevation. Distance between the points is 20 m. Elevation between grid points is calculated by interpolation.<HR></BLOCKQUOTE> Nearly on target. The tile itself is 20x20m, but the "distance between points" for elevation is actually smaller than that. Hard to give an exact number because a single 20x20 tile can have lots of different heights and patterns of heights within it. <BLOCKQUOTE>quote:</font><HR> Within the same 20 x 20 m grid you define "tiles" which you can assign a default terrain type (e.g. forest).<HR></BLOCKQUOTE> Correct. Each 20x20m tile is a specific terrain element, with possible additions (see below). <BLOCKQUOTE>quote:</font><HR> Additionally you use a grid with a ten times higher resolution (2x2 m) to add details like walls and hedges. They are abstracted as prisms with a 2x2 m base and a certain relative height. Absolute height of the (top of the) object is calculated by adding the interpolated terrain elevation. <HR></BLOCKQUOTE> Correct. Things like walls, building walls, roads, foxholes, shell craters, etc. are all done at this small 2x2m scale. Each has a defined height, which can (of course) be higher or lower than the one next to it. <BLOCKQUOTE>quote:</font><HR> Contrary to "walking" from (sub)tile to (sub)tile you use true VECTORS to calculate LOS. That is you calculate the actual intersection of the LOS with the actual terrain (I suppose one tile is split up into two triangles to do this). Some integer algorithm is used to determine which tiles (and subtiles) are crossed by the projection of the LOS on the horizontal plane such that you minimize the number of tiles you have to perform these calculations for, BUT the calculation itself is done in pure 3D geometry. <HR></BLOCKQUOTE> Right on the money. This is an area that 2D games simply can not touch. They use approximations for height and shape, not direct mathematical models. The smaller the scale of the 2D game the more that this matters (i.e. a squad level game is more affected by this than a divisional level game is). <BLOCKQUOTE>quote:</font><HR>Am I finally there ? Can we close this thread ? Can I go back to work ? Can I start the thread on pathfinding ?<HR></BLOCKQUOTE> Yup, time to go back to work! I would hold off on the pathfinding thing for a couple of weeks. We really haven't spent that much time on it at this point, so there isn't alot we can add to the discussion right now. Steve [This message has been edited by Big Time Software (edited 05-21-99).] Link to comment Share on other sites More sharing options...
Moon Posted May 21, 1999 Share Posted May 21, 1999 Hmmm? I don't know if the other people see the same, but I have a message right here in front of my eyes that say that Thomm is the author... but it's signed with Steve and it says "this message has been edited by Big Time Software"... Looks like something went wrong... (and I can't see Thomm's post also)... Link to comment Share on other sites More sharing options...
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