#Without knowing anything about the

1 messages · Page 1 of 1 (latest)

strange dirge
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they're taken from a plane mesh

hardy crystal
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you'd have to analyze the particular mesh you are looking at

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there's no guarantee about vertex ordering etc.

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you'll have to do some analysis of the triangles to find the opposing triangles and pair them up

strange dirge
hardy crystal
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basically - the vertex array is not enough. You need the triangles too.

strange dirge
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i have both

hardy crystal
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this is some complicated math. What's the goal here?

strange dirge
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i need to create tiles/cells out of the quads of that mesh

hardy crystal
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seems backwards

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I'd probably start with a grid and then project that grid onto the existing mesh.

strange dirge
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the goal is to given a terrain mesh, create a path finding grid data

hardy crystal
strange dirge
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can't, the end result of the grid will be written to a specific file format so I can load into my game server

hardy crystal
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why does that preclude NavMesh?

strange dirge
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basically for each cell I need the 4 heights of its points + if its walkable or not

strange dirge
bronze nova
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given an initial vertex, you can find all the trinagles that use it. Then check which of those triangles contains the the next point from your vertex list. repeat.

hardy crystal
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Does slope etc matter?

strange dirge
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nope

hardy crystal
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Then it's basically just a graph of triangles. You can find adjacent triangles by those which share an edge

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then all standard graph algorithms can be used

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including A*, Djikstra's, etc...

strange dirge
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the game uses A* to calculate paths, problem im trying to overcome is to given any mesh create the data in the format it understands

hardy crystal
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How are you using A* without a graph

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I'm going to assume you mean the A* pathfinding asset rather than the A* algorithm?

strange dirge
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the algorithm

hardy crystal
strange dirge
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we are able to read the original game formats and those files have the graph

hardy crystal
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go through all the triangles, build up an adjacency list

bronze nova
strange dirge
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for context:
we load the cells this way

            for (int i = 0; i < width * height; i++)
            {
                Vector4 heights = new Vector4();
                heights[0] = data.ReadFloat() * 0.2f;         // height 1
                heights[1] = data.ReadFloat() * 0.2f;         // height 2
                heights[2] = data.ReadFloat() * 0.2f;         // height 3
                heights[3] = data.ReadFloat() * 0.2f;         // height 4
                cells[i].Heights = heights;
                cells[i].type = GAT.TYPE_TABLE[data.ReadUInt()];    // type
            }```
then we ask for a cell this way
    ```public GAT.Cell GetCell(double x, double y) {
        uint index = (uint) (Math.Floor(x) + Math.Floor(y) * gat.width);

        return gat.cells[index];
    }```
strange dirge
bronze nova
strange dirge
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Im confused... the adjacency thing going to be responsible for giving me what I need to create the cells so I can input that into my A*, is that right?

bronze nova
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yes, to go from mesh to cells. but also, in the A*, each cell needs to know which cells are its neighbors to compute the path.

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@strange dirgelet me ask.. do you really need to start with the mesh itself? What if you started with a plain ol' rectange of x,y cells, to use in A*, (where neighbors are defined by their x,y index). Then after the path is computed, when you want to draw it, use the cell index to compute the appropriate position of the cell, on the mesh (using only the offets between a few verticies to detemine the draw/map size of each cell).

strange dirge
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It makes sense

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What I wanted to achieve was this, after it loads the ground plane it goes over each cell, split it into 16*16 chunks and creates a mesh overlay on top of the terrain to display the cell types

image.png
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but it's only capable of doing that because the game files provides each cell 4 height points

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and I'm unsure how to reverse that once I don't have the cell data and I suck at math

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I dont really care about the mesh itself, I just need to be able to create a bunch of cells using the correct height data

bronze nova
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hmmm.. I guess this depends a bunch of the format of the height data. e.g. is it provided in a 2d array (easy), or in a single array, row by row/column by column, totally random...

strange dirge
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its in a 1 dimension array

strange dirge
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(idk if that's what you mean)

bronze nova
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yep, thats exactly what I mean.. looks like row by row. So good you know how to transform an x,y coordinate into an array index. So neighbors of x,y are just (x-1,y) (x+1,y) (x,y-1) (x,y+1).. (though obviously you'll need to add a boundry check in there)

strange dirge
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I see, how should I find the heights of each point then? I know cells are 1 unit each, so the centres are 0.5f offset to each corner

bronze nova
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wouldn't that be the data stored in the height array you are using?

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e.g. heightArray[ToIndex(x,y)].height?

strange dirge
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I need to create the height array from a random plane/mesh plane

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That’s the problem I’m trying to solve 🤣

bronze nova
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check out perlin noise for that. It allows you to specify a 2d coordinate, and get back a random value.. whats cool about this kinda noise is that it changes "smoothly" so you get smoothly changing hills and valleys as you traverse coordinates..