Does anybody know how the GetNearestWater function work?

Martin Gühmann · October 13, 2003, 18:14

Acording to the slic documentation it takes two arguments. I was able to verify this. Also according to the slic documentation both arguments are location variables. Unfortunatly if I give it two locations I get a bounce message windows box in SlicDebug mode: Wrong Type of Argument.

OK while I was writing I had to test something and I figured out something more, so my question is at least anwered partly:

If I use something like this I get the windows bounce messege:

location_t MGLoc;
GetNearestWater(army[0].location, MGLoc);

But if I use this, I don't get a bounce message:

location_t MGLoc;
GetNearestWater(army[0].location, MGLoc.location);

The only problem is the function know returns the distance to that tile but it doesn't fill the location variable.

-Martin

Peter Triggs · October 13, 2003, 19:53

You got further than me. My notes just say "Must be broken, keeps giving 'wrong type of argument' errors."

Martin Gühmann · October 14, 2003, 11:44

Well at least I can use it for determining the direction of the water tile. And it can be used to know whether the location is a water tile or not:

if(GetNearestWater(army[0].location, MGLoc.location) > 0){
// --> army[0].location is land
}
if(GetNearestWater(army[0].location, MGLoc.location) == 0){
// --> army[0].location is sea
}

-Martin

J Bytheway · October 15, 2003, 09:47

How do you determine the direction of the water tile? You said it returned the distance - did you mean that? If you can obtain the direction you can iterate to find the nearest water tile (or at least something close to it).

Martin Gühmann · October 15, 2003, 10:16

Quote:

Originally posted by J Bytheway
How do you determine the direction of the water tile? You said it returned the distance - did you mean that? If you can obtain the direction you can iterate to find the nearest water tile (or at least something close to it).

It does return the Distance as advertised. If you look on the distance of the neigbour tiles, you can find the direction, becaus ethe neighbor that lies in the same direction is close to the water tile. Well I already had before a function that can find the direction of one tile respective of another tile. So the function looks like this:

Code:

////////////////////////////////////////////////////////
//MG_GetWaterDirection                                //
//                                                    //
//Parameter: location_t startLoc                      //
//                                                    //
//Return Value:                                       //
//The direction in that the nearest water tile of     //
//startLoc lies. Or if startLoc is a water tile it    //
//returns 8.                                          //
//                                                    //
//Remarks:                                            //
//none                                                //
////////////////////////////////////////////////////////

int_f MG_GetWaterDirection(location_t startLoc){
	location_t MGLoc;
	location_t MGStartLoc;
	location_t MGDummyLoc;
	MGStartLoc = startLoc;
	int_t MGDistance;
	int_t MGNewDistance;
	int_t MGDirection;
	int_t j;
	//GetNearestWater should fill MGDummyLoc with location of the nearest water tile
	//but in fact it is not filled, the function returns only the distance of that tile.
	MGDistance = GetNearestWater(MGStartLoc.location, MGDummyLoc.location);
	if(MGDistance == 0){
		return 8;
	}
	for(j = 0; j < 8; j = j + 1){
		GetNeighbor(MGStartLoc, j, MGLoc);
		MGNewDistance = GetNearestWater(MGLoc.location, MGDummyLoc.location);
		if(MGNewDistance < MGDistance){
			MGDistance = MGNewDistance;
			MGDirection = j;
		}
	}
	return MGDirection;
}

-Martin

J Bytheway · October 15, 2003, 14:16

Clever

. So you can write a function to obtain a nearest water tile by repeating the above process until you reach water. Of course, this is likely to be relatively slow, but perhaps not too bad. You could of course save the information in an array for any tile you need to calculate so that you never repeat the calculation for that tile, but it probably wouldn't be worthwhile to.

Immortal Wombat · October 15, 2003, 14:17

Code:

location_t TheWatersEdge;

Functional_GetNearestWater(location_t startLoc)
{
// assuming there is water on the map...
location_t theLoc;
location_t theOtherLoc;
int_t i;
theLoc = startLoc;
     while(GetNearestWater(army[0].location, MGLoc.location) > 0){
         i = MG_GetWaterDirection(theLoc);
         GetNeighbor(theLoc,i,theOtherLoc);
         theLoc = theOtherLoc;
    }
    TheWatersEdge = theLoc;
}

Immortal Wombat · October 15, 2003, 14:20

x=-post

J Bytheway · October 15, 2003, 14:22

Indeed - I just came back to raise the question of what happens when there is no water, but you beat me to it

.

Martin Gühmann · October 16, 2003, 11:21

Quote:

Originally posted by J Bytheway
Indeed - I just came back to raise the question of what happens when there is no water, but you beat me to it

.

In that case GetNearestWater(army[0].location, MGLoc.location) returns 0 and not -1 as I expected. So it is not the best way to figure out wheather you have to do it with a land or a sea tile.

-Martin

Immortal Wombat · October 16, 2003, 18:21

Do a terrain check on a known land tile (like under a city) beforehand.

J Bytheway · October 17, 2003, 10:08

Under a city might not be the best choice - I can concieve of scenarios that start you with sea cities rather than land ones.

I thought that there was a function to check terrain types - I know I used one in CTP1, surely that must be a faster way to check whether a tile is water or not.

Martin Gühmann · October 17, 2003, 10:56

Quote:

Originally posted by J Bytheway
Under a city might not be the best choice - I can concieve of scenarios that start you with sea cities rather than land ones.

I thought that there was a function to check terrain types - I know I used one in CTP1, surely that must be a faster way to check whether a tile is water or not.

So there is such a function in CTP1. If this is true and the function is still in CTP2 than Peter and I weren't able to find it.

-Martin

J Bytheway · October 18, 2003, 07:02

If I were using my own computer I'd have a look now and see what it was, but I can't. I'll try and remeber to do so the next time I can and get back to you.

J Bytheway · October 19, 2003, 07:04

Yep, there was, and it was called TerrainType. e.g. I used

Code:

if (TerrainType(city.location) == 13)

to test for space cities. I doubt that you could have missed that if it still existed, though.

There was also an IsUnderseaCity(city) function, which might be useful if it still exists, and an IsSpaceCity - but that one didn't work - hence the above workaround.

Peter Triggs · October 19, 2003, 08:22

Ahh, now I remember:

Code:

int_f CTC_IsSeaTerrain(location_t theLoc){

    location_t tmpLoc;
    tmpLoc=theLoc;
    if ((9 < TerrainType(tmpLoc) && TerrainType(tmpLoc) < 17) 
|| TerrainType(tmpLoc)==22 || TerrainType(tmpLoc) ==23 ){
         return 1;
    }
    return 0;

}

Martin Gühmann · October 19, 2003, 10:10

Quote:

Originally posted by J Bytheway
Yep, there was, and it was called TerrainType. e.g. I used

Code:

if (TerrainType(city.location) == 13)

to test for space cities. I doubt that you could have missed that if it still existed, though.

Well here is my MG_IsLand function:

Code:

int_f MG_IsLand(location_t theLoc){
location_t MGLoc;
MGLoc = theloc;
	return((TerrainType(MGLoc)<=9)
	||((TerrainType(MGLoc)>=18)
	&& (TerrainType(MGLoc)<=21))
	);
}

As you can see I use the TerrainType as well. But that was not that I was looking for. For instance if I change the order of the terrains in the terrain.txt this function above wouldn't work.

Quote:

Originally posted by J Bytheway
There was also an IsUnderseaCity(city) function, which might be useful if it still exists, and an IsSpaceCity - but that one didn't work - hence the above workaround.

There is also a IsUnderSeaCity function and I think also a IsSpaceCity function. Well I haven't tested it. But I doubt that the IsUnderSeaCity function works, because whenever undersea tunnels are under a city the terrain is considered as land tile and therefore also the undersea cities, that's the cause of the sea city sprite bug. Well in that case even a build in IsLand function wouldn't work.

-Martin

J Bytheway · October 19, 2003, 12:36

Hmm... I see the problem.

Perhaps you should try GetNearestWater on a sea city tile and see whether it returns 1 or 0 - If it is being treated as land as you say then it might return 1 and then you can indeed test whether there is any water on the map by using GetNearestWater on the capital city.

Immortal Wombat · October 19, 2003, 17:12

You can in place of numbers use the DB-references in that function:

Code:

if(TerrainType(tmpLoc) == TerrainDB(TERRAIN_PLAINS)){

For instance. Although in fact the converse would be better, checking it's not a sea terrain rather than is a land terrain, because land terrains are more likely to be added as dummys in scenarios, and AFAIK nobody has ever published anything with an added sea terrain.

Martin Gühmann · October 28, 2003, 16:27

Looks like GetNearestWater scans the whole map for water tiles and returns finally the shortest distance.

-Martin