Finding a Position on a 2D Map that meets several criteria - c#

as my personal project i develop a game to which users can join at any time.
I have a tiled worldmap that is created from a simple Bitmap which has resources at random positions all over the map except for oceans.
When a player joins i want to create his starting position at a place that has at least 1 tile of each of the 4 resources in range (circle with a still to decide diameter, i think about 3-4 tiles) but no ocean tiles (Tile.Type != "ocean") and not conflicting with a field belonging to another player (Tile.Owner == null).
The map size can vary, currently it's 600x450 and it's implemented as a simple Array: Tile[][] with Tile.Resource being either null or having Tile.Resource.Type as a string of the resource name (as it's configurable by plaintext files to fit any scenery i want to put it in, so no built-in enums possible).
I currently have a loop that simple goes through every possible position, checks every field in range and counts the number of each resource field and discards it if there are none for one of them or if one of them belongs to a player or is an ocean field.
I would prefer if it finds a random position but thats not a requirement, mono-compatibility however is a requirement.
What would be the best way to implement an algorithm for that in C#?
Edit
The Area of players can and will increase/change and resources can be used up and may even appear randomly (=> "Your prospectors found a new goldmine") so pre-calculated positions will propably not work.

Instead of looping through all your positions, why don't you loop through all your resources? Your resources are likely to be more scant. Then pick one of the sets of resources that meet your clustering criterion.

You might consider simulated annealing ... it's not very complex to implement. You have a set of criteria with certain weight, and randomly "shake" the position at a certain "temperature" (the higher the temp, the greater the radius the position may randomly move within, from it's previous position), then when it "cools" you measure the value of the position based on the total weights and subtract negative things, like spawning too close to where they died, or next to other players, etc..., if the value is not within a certain range, you decrease the temperature, but "shake" the positions again, cool down, check weights and overall value, repeat until you get an acceptable solution.
Simulated annealing is used in map making, to label cities and features with maximum clarity, while staying within range and minimizing overlap. Since it's a heuristic approach there is no guarantee that there will be an optimal solution, so you keep "lowering the temp" and eventually just choose the best result.

Let's suppose that once your map is created you don't have to create a new one often.
Just add the following to each Tile and calculate them once after your map was generated:
-int NrOceanTiles
-int NrResourceA
-int ...
Now when you want to get a tile you can do it quite a bit faster:
IEnumerable<Tiles> goodTiles = tiles.Where(tile => tile.NrResourceA >= 1 && tile.NrResourceB >= 2);
Tile goodTile = goodTiles.ElementAt(randomI);

Predefined data would still be the best way forward.
As modifying the map size, and adding/losing resources would not happen as often, just update this data table when they do happen. Perhaps you could do the map/resource changes once per day, and have everything done in a daily database update.
In this way, finding a valid location would be far faster than any algorithm you implement to search all the tiles around it.

If the game isn't going to be designed for a huge number of players, most games implement "start spots" on the map. You'd hand-pick them and record the positions in your map somehow, probably similar to how you're implementing the map resources (i.e., on that spot, there exists an item you can pick up, but on top of the tile map).
Since the resources spawn at random, you could either not spawn resources on the start spots (which could be visible or not), or simply not spawn a player at a start spot on which there is a resource (or look within a 9-cell box to find a close alternate location).
Certainly you would want to hold the set of possible starting locations and update it as resources are created and consumed.

It seems like your best bet is to calculate open locations at map generation. Have your start location calculation function optionally take grid location and size or rectangle corners.
Have a list for Free locations and Occupied locations. Player occupies territory? Move resources in range to the Occupied list. Player gets crushed mercilessly? Move resources in range to the Free list. Resource eliminated? Delete any locations that used it in your Open/Occupied lists. Resource added? Recalculate using your effect radius to determine effected area. When your map area expands, just run the initial calculations on the new section of your grid + effect radius and add the new locations.
Then you just have to set the events up and pick a random Free value when someone joins.

Related

Indoor path-finding c# wpf

I am currently developing an indoor path-finding. I have multiple floors and different rooms. How will I be able to implement a* algorithm in the images of each floor using c# wpf?
I use spatial A* for the game I'm working on.
Spatial A* uses movement "cost" to work out the best route between two points. The cost mentions is supplied by an array. Usually a 2d array of number - float uint or whatever.
Moving through a square/cell at position x,y thus costs the number in that 2d array. EG costs[2,3] would be the cost of movement through the cell 2 cells across from the left and 3 down from the top of an imaginary grid projected onto your "room".
If the move is diagonal then there's also a multiplier to consider but that will be in whichever implementation you go with.
Hence you need a 2d costed array per floor.
You would need to somehow analyse your pictures and work out an appropriate size for a costed cell. This should match the smallest size of a significant piece of terrain in your floor.
You would then translate your picture into a costed array. You've not told us anywhere near enough to tell you specifically how to do that. Maybe that would have to be a manual process though.
Blocked cells get the max number, empty cells get 1. Depending on your requirements that might be that. Or alternatively you might have actors leaping tables and chairs etc.
You give the pathing algorithm start and target location (x,y), the appropriate costed array and it works out the cheapest route.

Generate hexagonal islands

I'd like to generate flat islands existing of multiple hexagons. So far I've been able to create hexagonal meshes with code, but can't figure out how to position them in groups, creating a randomly shaped island. (Any shape that's not a perfect circle, square etc.) I think I would need an algorithm, that places hexagon tiles next to multiple sides of an existing tile. If you can help me with an idea for an algorithm, then that would be great.
Are you looking for something like this?
Place 1 hexagon.
for i in (islandSize-1):
Scan all hexagons for open sides. Place open sides in a list named hexBorders
Choose a random index in hexBorders, attach a new hexagon there
That algorithm should give you a fairly roundish island, roughly centered on the original hex, because older hexes have more chances to get picked.
You can tune this shape by preferring either newer or older hexagons (e.g. you could include hexagon age in hexBorders, and adjust your random choice so it prefers younger hexes).
Recently I was also doing random map generator for tile based map and hit a wall while try to add more advanced features (in tile space) the realism of output was not good. I decided to create a 2D/3D image based map and then convert it to tile map. Still not finished with adding all the features I want but the result is already a magnitude better then before:
map generator
see my simple random map generator in C++. It is based on Diamond&Square algorithm with some tweaking to obtain island like maps.
conversion to tile-map
Simply map Cartesian pixel into your hexagonal grid layout. You can also compute the average of some area instead of using single pixel per cell/tile.
For 3D tile maps this will produce "voxel-ated" output so you need to add additional filtering see
How to procedurally generate tile map for some ideas.
Since is a pretty open ended question, this article by Red Blob Games about hexagonal data structures would be an excellent place to start. The author describes how you can use 2D arrays to store the hexagons, and how you can iterate through them.
Once you understand the relation of hexagons to one another you can start to iterate through them in interesting ways.
Probably the easiest way to generate an "island" would be with a SIR-type model, also known as an epidemic model. This is a model that is commonly used by researchers to simulate the spread of infectious disease, but I've found that you can also use it to generate pseudo-natural shapes (like an island!). SIR stands for Susceptible-Infectious-Recovered. Those are the three states of a "cell", or in this case hexagon. At any given step of the algorithm, an infected cell can infect a neighboring cell. Think about it like this: at the start of your algorithm, one hexagon is "infected" (land) and the rest are not (water). At each iteration of the algorithm, cells adjacent to an infected cell have a chance (say, 1 in 10) of being infected as well (turning into land). After many iterations, you'll find that the shape of the infected group of hexagons is pretty random looking, but they're all touching. For a grid-bsed example, here's some images I've uploaded to imgur. Pseudo-code for this algorithm is below.
cellsToDo = [originCell]
for 100 iterations:
for each cell in cellsToDo:
for each neighbor to the current cell:
if randomValueBetween(0, 10) == 1:
set the current cell as infected
add the current cell to the cellsToDo list
There are definitely other algorithms, but I'd start with learning how the hexagons are related to each other and can be stored.

How to randomly place objects as player move around in an infinity map without overlap?

I trying to make a game where player only move forward in an infinity map, and the path (just thing of them like points, the path is only the visual) is procedurally generated. I want those path to have different length (something like the tree of life, but only branches of the selected path are generated).
This is how I generate branches without overlap:
List<Vector3> everyPos; //predetermined position
public void Spawn(int amount)
{
List<Vector3> possiblePos = new List<Vector3>(everyPos);
for (int i = 0; i < amount; i++)
{
int index = Random(0, possiblePos.Count); //Find a random position
SpawnObjectAt(currentPosition+possiblePos[index]));//Create a point there
possiblePos.RemoveAt(index); //Remove that position from the list
}
}
The problem is , look at this image(I can't embed image yet):
Red is where player start, green is possible spawn position in the first move.
If there are 2 point spawned at 1 and 2, player choose point1, then the possible position in the second time will be a point in the black zone, which include point2, so if I keep continue there will eventually overlap.
How can I avoid this? I'm making a mobile game so I don't want to cache every single point. Any help would be really appreciated! Thanks!
This is a small web game that have somewhat similar mechanic to what I trying to achieve: newgrounds.com/portal/view/592325/
This is an attempt here to answer, but honestly, you need to provide more information.
Depending on the language you are writing in, you can handle this differently. You may need dynamic allocation, but for now lets assume, since your idea is quite small, that you can just do one large array predefined before compile time.
I assume you know how to make an array, so create one with say, 500 length to start. If you want to 'generate' a link like they did in that game, you simply need a random function, (there is a built in library in pretty much every language I think) and you need to do a little math.
Whatever language you use will surely have a built in graphics library, or you can use a popular easy to use one. I'll just draw a picture to make this clear.
There are a number of ways you can do this mathematically as shown in the image, using angles for example, the simplest way, however, is just to follow the boxes.
If you have worked with graphics before, you know what a vector is, if not, you will need to learn. The 9 vectors presented in this image (0,1) (1,0) (1,1) etc. can be created as vector objects, or even stored as individual ints.
To make your nodes 'move' into another path, you can simply do a rand 1-9 and then correlated the result to one of 9 possible vectors, and then add them to your position vector. It is easiest to do this in array and just use the rand int as the index. In most c derived languages you do that like this:
positionVector += changeVectorArray[rand(1,9)];
You then increment your position vector by one of the 9 vectors as shown above.
The simplest way of making the 'path' is to copy the position before you add the change vector, and then store all of the changes sequentially in another 'path' array.
To show the path on screen, simply draw a line between the first and second, second and third, third and forth elements of your path array. This formula (of joining lines) is discrete mathematics if I'm not mistaken, and you can do much more complicated path shapes if you want, but you get the gist.
That should at least start you off. Without more info I can't really help you.
I could go off on a tangent describe a bunch of different ways you can make this happen differently but its probably easier if you just ask for specifics.
EDIT>>>
Continuing with this answer, yes, looking at it now, the nodes can definitely overlap. To solve this problem you could use collision detection, every time you generate a new 'position', before adding it and drawing the line you have to loop through your array like this:
boolean copy = true;
for(int i = 0; i < getLength(pathArray); i++){
if( newVector == pathArray[i]){
copy=false;
}
}
Then of course, if copy still is true, copy the new position int the pathArray. NOTE: this whole solution is sloppy as hell, and as your array gets larger, your program is going to take longer and longer to search through that loop. This may not also guarantee that the path goes in one direction, but it is likely. And note that the lines will still be able to overlap each other, even though the position vectors can't be on top of one another.
All this considered, I think it will work, the optimization is up to you. I would suggest that there is probably a much more efficient solution using a discrete formula. You can also use such a formula to make the path go in particular directions and do other more complicated things.
You could also quite easily apply constraints on your random rolls if you want to make the path go in a particular direction. But there are so many ways of doing this I can't begin to explain. You could google path-finding algorithms for that.
Good luck.

Procedurally Generated Structures over large quantitys of chunks in 3D Terrain Generator

I am creating large scale worlds using 16*16*16 voxel chunks which are stacked up to 32*32*32 in dimensions and I have hit a bit of a Bump in the road so to speak.
I want to create large structures that span 20+*20+*20+ chunks in volume which are created from procedurally generated structures as well as using templates for some of the content. Now I have an issue. The visual render range is up to 32*32*32 chunks and while I have up to maybe 40*40*40 chunks held in memory at a time when possible.
The structures can be anything like towns, dungeons and roads. I was thinking something like perlin worms for roads and just lay them over the terrain in the x,z and then analyze the path for bridges etc..
The structures and collection of structures need to be pre-generated before the player is within visual range or work more like perlin noise does for heightmaps (best solution). (to avoid the players seeing the generator at work). They also need to be consistent with the world seed every time.
I have thought about this a bit and have 2 possible solutions.
1) Generate the structures based on a point of origin for the structure generator.
This causes several issues though as even if I generate from the center of the structure, the structures can easily cross into the potential visual range of the player.
2) Pre-Generate "unreachable" chunks and then page them in and out in order to generate the structures using the above method.
This also seems rather unnecessary.
Both methods need to analyze the terrain in large quantities for a valid location to spawn the structures.
I was hoping somebody might have a more organic solution or even just a simpler solution that doesn't require me to "Look" so far ahead.
Thank you in advance.
EDIT:
I had an idea for dungeon generation in which I generate point clouds/nodes for rooms.
Steps:
1) When the generator finds a "node" it creates an x, y and z size to create a box basing it from the originator point of the room** (centre or corner of the room) and the room type.
**x,y,z relative to 0,0,0 worldspace calculated like so new Vector3((chunkX*16)+voxelX,(chunkY*16)+voxelY,(chunkZ*16)+voxelZ)
2) Once a room size is calculated, check for overlaps and if one is found do one of several things.
If the room overlap is high up lower it down till either the roof or the floor are flush. If the roof is flush build a stairs up to the room and remove the walls that intersect.
3) Look Down, North and East for a room maybe with a small cone and attempt to create a hallway between them.
This would probably work somewhat, especially if the center of the dungeon is the main hall/boss room.
This would be different for towns, cities, and surface dungeons. Still seems a little choppy though. Any ideas?
I faced a similar problem for a Minecraft mod I am writing. I want to have a number of overlapping "empires" which each create structures. But I don't want the structures to step on each other.
So, for this, I broke the world into arbitrary sized tiles. (Compare to your 32x32x32 regions.) I also came up with a "radius of influence". This is how far from the center point that it could create structures. Each tile had an instance of a provider class assigned to it with a unique seed.
Two methods on this class were provided for structure generation.
First, was a function that would return where it wanted to create structures. But only to the resolution of chunks. (Compare to your 16x16x16 block sets.) Each provider class instance had a priority, so in the case of two providers trying to rezz a structure in the same chunks, the higher priority one would win.
The second function would be passed a world instance, and one of the data items returned by the first function and would be asked to actually create it.
Everything pieces together like this:
We get a request to resolve a certain chunk of the world. We work out the provider for the tile the chunk is in, and then all the providers for all the tiles that are within the maximum radius of that tile. We now have every provider that could influence this chunk. We call the first function on each of them, if they haven't been called already, and register what chunks each of them has claimed into a global map.
At this point, we've consulted everything that could have an influence on this chunk. We then ask that registry if someone has claimed this chunk. If so, we call back into that provider (method #2) with the chunk and the world instance and get it to draw the bits for this part of its structure.
Does that give you enough of an idea for a general approach to your problem?

Optimising movement on hex grid

I am making a turn based hex-grid game. The player selects units and moves them across the hex grid. Each tile in the grid is of a particular terrain type (eg desert, hills, mountains, etc) and each unit type has different abilities when it comes to moving over the terrain (e.g. some can move over mountains easily, some with difficulty and some not at all).
Each unit has a movement value and each tile takes a certain amount of movement based on its terrain type and the unit type. E.g it costs a tank 1 to move over desert, 4 over swamp and cant move at all over mountains. Where as a flying unit moves over everything at a cost of 1.
The issue I have is that when a unit is selected, I want to highlight an area around it showing where it can move, this means working out all the possible paths through the surrounding hexes, how much movement each path will take and lighting up the tiles based on that information.
I got this working with a recursive function and found it took too long to calculate, I moved the function into a thread so that it didn't block the game but still it takes around 2 seconds for the thread to calculate the moveable area for a unit with a move of 8.
Its over a million recursions which obviously is problematic.
I'm wondering if anyone has an clever ideas on how I can optimize this problem.
Here's the recursive function I'm currently using (its C# btw):
private void CalcMoveGridRecursive(int nCenterIndex, int nMoveRemaining)
{
//List of the 6 tiles adjacent to the center tile
int[] anAdjacentTiles = m_ThreadData.m_aHexData[nCenterIndex].m_anAdjacentTiles;
foreach(int tileIndex in anAdjacentTiles)
{
//make sure this adjacent tile exists
if(tileIndex == -1)
continue;
//How much would it cost the unit to move onto this adjacent tile
int nMoveCost = m_ThreadData.m_anTerrainMoveCost[(int)m_ThreadData.m_aHexData[tileIndex].m_eTileType];
if(nMoveCost != -1 && nMoveCost <= nMoveRemaining)
{
//Make sure the adjacent tile isnt already in our list.
if(!m_ThreadData.m_lPassableTiles.Contains(tileIndex))
m_ThreadData.m_lPassableTiles.Add(tileIndex);
//Now check the 6 tiles surrounding the adjacent tile we just checked (it becomes the new center).
CalcMoveGridRecursive(tileIndex, nMoveRemaining - nMoveCost);
}
}
}
At the end of the recursion, m_lPassableTiles contains a list of the indexes of all the tiles that the unit can possibly reach and they are made to glow.
This all works, it just takes too long. Does anyone know a better approach to this?
As you know, with recursive functions you want to make the problem as simple as possible. This still looks like it's trying to bite off too much at once. A couple thoughts:
Try using a HashSet structure to store m_lPassableTiles? You could avoid that Contains condition this way, which is generally an expensive operation.
I haven't tested the logic of this in my head too thoroughly, but could you set a base case before the foreach loop? Namely, that nMoveRemaining == 0?
Without knowing how your program is designed internally, I would expect m_anAdjacentTiles to contain only existing tiles anyway, so you could eliminate that check (tileIndex == -1). Not a huge performance boost, but makes your code simpler.
By the way, I think games which do this, like Civilization V, only calculate movement costs as the user suggests intention to move the unit to a certain spot. In other words, you choose a tile, and it shows how many moves it will take. This is a much more efficient operation.
Of course, when you move a unit, surrounding land is revealed -- but I think it only reveals land as far as the unit can move in one "turn," then more is revealed as it moves. If you choose to move several turns into unknown territory, you better watch it carefully or take it one turn at a time. :)
(Later...)
... wait, a million recursions? Yeah, I suppose that's the right math: 6^8 (8 being the movements available) -- but is your grid really that large? 1000x1000? How many tiles away can that unit actually traverse? Maybe 4 or 5 on average in any given direction, assuming different terrain types?
Correct me if I'm wrong (as I don't know your underlying design), but I think there's some overlap going on... major overlap. It's checking adjacent tiles of adjacent tiles already checked. I think the only thing saving you from infinite recursion is checking the moves remaining.
When a tile is added to m_lPassableTiles, remove it from any list of adjacent tiles received into your function. You're kind of doing something similar in your line with Contains... what if you annexed that if statement to include your recursive call? That should cut your recursive calls down from a million+ to... thousands at most, I imagine.
Thanks for the input everyone. I solved this by replacing the Recursive function with Dijkstra's Algorithm and it works perfectly.

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