Right now I am trying to implement terrain generation. I am using msvc visual studio 2019. And when I got to decreasing level of details in my function, generation started to be very glitchy. Everything is fine when I am not using any of level of details decreasing values. But everything changes after 1 and more - generation starts to be glitchy and generates atifacts. Here is some examples.

This one is correct as it should be. In my function this stands for parameter 0 in LevelOfDetails.

And Incorect examples. LevelOfDetails=1:

LevelOfDetails=3-6:

This is a function for generating meshes:

static void
GenerateTerrainMesh(world* World, noise_map* NoiseMap, float HeightMultiplier, int LevelOfDetail)
{
    int Width  = NoiseMap->Width;
    int Height = NoiseMap->Height;
    //float TopLeftX = (Width - 1)  / (-2.0f);
    //float TopLeftZ = (Height - 1) / ( 2.0f);

    if(LevelOfDetail < 0) LevelOfDetail = 0;
    if(LevelOfDetail > 6) LevelOfDetail = 6;

    int SimplificationInc = (LevelOfDetail == 0) ? 1 : (LevelOfDetail * 2);
    int VerticesPerLineX  = (Width  - 1) / SimplificationInc   1;
    int VerticesPerLineY  = (Height - 1) / SimplificationInc   1;

    InitializeMeshTerrain(World, VerticesPerLineX, VerticesPerLineX);

    int VertIndex = 0;
    int TrigIndex = 0;
    for(int Y = 0; Y < Height; Y  = SimplificationInc)
    {
        for(int X = 0; X < Width; X  = SimplificationInc)
        {
            World->Terrain.Vertices[VertIndex] = V3((float)X, HeightMultiplier * HeightFlatten(World->NoiseMap.Values[Y*World->NoiseMap.Width   X]).y * HeightMultiplier, (float)Y);
            World->Terrain.UVs[VertIndex]      = V2(X/(float)Width, Y/(float)Height);

            if((X < (Width - 1)) && (Y < (Height - 1)))
            {
                AddTriangle(World, &TrigIndex, VertIndex, VertIndex   VerticesPerLineX   1, VertIndex   VerticesPerLineX);

                AddTriangle(World, &TrigIndex, VertIndex   VerticesPerLineX   1, VertIndex, VertIndex   1);
            }

            VertIndex  = 1;
        }
    }
}

And helper functions, but there should not be any errors:

static void
InitializeMeshTerrain(world* World, int Width, int Height)
{
    World->Terrain.VerticesCount = Width * Height;
    World->Terrain.FacesCount    = (Width - 1)*(Height - 1)*2;
    World->Terrain.UVCount       = Width * Height;

    World->Terrain.Faces    = (face*)malloc(sizeof(face)*World->Terrain.FacesCount);
    World->Terrain.Vertices = (v3*)malloc(sizeof(v3)*World->Terrain.VerticesCount);
    World->Terrain.UVs      = (v2*)malloc(sizeof(v2)*World->Terrain.UVCount);
}

static void
AddTriangle(world* World, int* Index, int a, int b, int c)
{
    World->Terrain.Faces[*Index].a = a;
    World->Terrain.Faces[*Index].b = b;
    World->Terrain.Faces[*Index].c = c;

    *Index  = 1;
}

What problem could be there? Thank you. UPD: I added some additional data to work with such as Mesh Data and Vertices Data for each LevelOfDetail:
Correct:
LevelOfDetail=0
Incorect 1:
Incorect LevelOfDetail=1
Incorect 4:
Incorect LevelOfDetail=4
Incorect 6:
Incorect LevelOfDetail=6

CodePudding user response：

Like PaulMcKenzie mentioned, seams that I just used Even Numbers instead of Odd numbers and that was entirely of the problem. And even more, sometimes It couldn't work correctly, because I used too small numbers for generating mesh grid like 90 or 100. So, for correct working of this mesh algorithm Width should be divisible on 1, 2, 4, 6, 8, 10 and 12, and then It should work pretty fine