static void smooth(DenseGrid2f grid, DenseGrid2f tmp, float alpha, int rounds)
{
if (tmp == null)
{
tmp = new DenseGrid2f(grid.ni, grid.nj, 0);
}
int ni = grid.ni, nj = grid.nj;
for (int k = 0; k < rounds; ++k)
{
tmp.assign_border(1, 1);
for (int j = 1; j < nj - 1; ++j)
{
for (int i = 1; i < ni - 1; ++i)
{
float avg = grid[i - 1, j] + grid[i - 1, j + 1]
+ grid[i, j + 1] + grid[i + 1, j + 1]
+ grid[i + 1, j] + grid[i + 1, j - 1]
+ grid[i, j - 1] + grid[i - 1, j - 1];
avg /= 8.0f;
tmp[i, j] = (1 - alpha) * grid[i, j] + (alpha) * avg;
}
}
grid.copy(tmp);
}
}
static void diffuse(DenseGrid2f grid, float t, Func <int, int, bool> skipF)
{
int ni = grid.ni, nj = grid.nj;
DenseGrid2f dilated = new DenseGrid2f(grid);
for (int j = 1; j < nj - 1; ++j)
{
for (int i = 1; i < ni - 1; ++i)
{
if (skipF != null && skipF(i, j))
{
continue;
}
if (grid[i, j] < 0)
{
foreach (Vector2i o in gIndices.GridOffsets8)
{
float df = (o.LengthSquared > 1) ? -1f : -0.707f;
df *= t;
dilated[i + o.x, j + o.y] = Math.Min(dilated[i + o.x, j + o.y], df);
//dilated[i + o.x, j + o.y] += df;
}
}
}
}
grid.swap(dilated);
}
static DenseGrid2i binarize(DenseGrid2f grid, float thresh = 0)
{
DenseGrid2i result = new DenseGrid2i();
result.resize(grid.ni, grid.nj);
int size = result.size;
for (int k = 0; k < size; ++k)
{
result[k] = (grid[k] < thresh) ? 1 : 0;
}
return(result);
}
void process_version2(DenseGrid3f supportGrid, DenseGridTrilinearImplicit distanceField)
{
int ni = supportGrid.ni, nj = supportGrid.nj, nk = supportGrid.nk;
float dx = (float)CellSize;
Vector3f origin = this.GridOrigin;
// sweep values down layer by layer
DenseGrid2f prev = supportGrid.get_slice(nj - 1, 1);
DenseGrid2f tmp = new DenseGrid2f(prev);
Bitmap3 bmp = new Bitmap3(new Vector3i(ni, nj, nk));
for (int j = nj - 2; j >= 0; j--)
{
// skeletonize prev layer
DenseGrid2i prev_skel = binarize(prev, 0.0f);
skeletonize(prev_skel, null, 2);
//dilate_loners(prev_skel, null, 2);
if (j == 0)
{
dilate(prev_skel, null, true);
dilate(prev_skel, null, true);
}
for (int k = 1; k < nk - 1; ++k)
{
for (int i = 1; i < ni - 1; ++i)
{
bmp[new Vector3i(i, j, k)] = (prev_skel[i, k] == 1) ? true : false;
}
}
smooth(prev, tmp, 0.5f, 5);
DenseGrid2f cur = supportGrid.get_slice(j, 1);
cur.set_min(prev);
for (int k = 1; k < nk - 1; ++k)
{
for (int i = 1; i < ni - 1; ++i)
{
float skelf = prev_skel[i, k] > 0 ? -1.0f : int.MaxValue;
cur[i, k] = Math.Min(cur[i, k], skelf);
if (cur[i, k] < 0)
{
Vector3d cell_center = new Vector3f(i * dx, j * dx, k * dx) + origin;
if (distanceField.Value(ref cell_center) < -CellSize)
{
cur[i, k] = 1;
}
}
}
}
for (int k = 1; k < nk - 1; ++k)
{
for (int i = 1; i < ni - 1; ++i)
{
if (is_loner(prev_skel, i, k))
{
foreach (Vector2i d in gIndices.GridOffsets8)
{
float f = 1.0f / (float)Math.Sqrt(d.x * d.x + d.y * d.y);
cur[i + d.x, k + d.y] += -0.25f * f;
}
}
}
}
for (int k = 1; k < nk - 1; ++k)
{
for (int i = 1; i < ni - 1; ++i)
{
supportGrid[i, j, k] = cur[i, k];
}
}
prev.swap(cur);
}
VoxelSurfaceGenerator gen = new VoxelSurfaceGenerator()
{
Voxels = bmp
};
gen.Generate();
Util.WriteDebugMesh(gen.Meshes[0], "c:\\scratch\\binary.obj");
}
