LevelSetField

C++: phynexis::utils::LevelSetField Python: phynexis.utils.LevelSetField Header: src/utils/level_set_field.hpp

Represents a level set function $\phi$ on a regular 3D grid. Used for implicit surface representation, interface tracking, and shape operations.

Constructor

LevelSetField()

Creates a level set field with default grid parameters:

• Corner: (-0.5, -0.5, -0.5)
• Spacing: 0.05
• Dimensions: (21, 21, 21)

Methods

get_corner()

Return the grid corner position.

Returns:Vec3d

get_spacing()

Return the grid spacing.

Returns:float

get_dimensions()

Return the grid dimensions.

Returns:Vec3i

set_corner(corner)

Set the grid corner.

Parameters:

Parameter	Type	Description
corner	Vec3d	Lower corner of the grid

set_spacing(sp)

Set the grid spacing.

Parameters:

Parameter	Type	Description
sp	float	Cell spacing

set_dimension(dim)

Set the grid dimensions.

Parameters:

Parameter	Type	Description
dim	Vec3i	Number of cells in each dimension

get_phi(id) / set_phi(id, value) / phi(i, j, k)

Access level set values at grid cells.

Parameters:

Parameter	Type	Description
id	Vec3i	Grid cell index
i, j, k	int	Individual indices
value	float	New phi value

init_from_sdf_calculator(sdf)

Initialize phi values by sampling an SDFCalculator.

signed_distance(pos)

Interpolate signed distance at an arbitrary point in space.

gradient_interpolate(pos)

Interpolate gradient at a point.

gradient_minus(id) / gradient_plus(id)

Compute gradient at a grid point using backward/forward differences.

reinitialization() / reinitialization(iterations, dt)

Reinitialize the level set function to maintain signed distance property.

is_initialized()

Check if phi_table has been allocated.

Returns:bool

index_3d(i, j, k)

Compute the flat array index for a 3D grid coordinate.

Parameters:

Parameter	Type	Description
i	int	First dimension index
j	int	Second dimension index
k	int	Third dimension index

Returns: int — Flat array index

get_phi_table()

Return a reference to the internal phi table (flat VecX<double> array).

Returns: list[float] — Internal phi values

Example

import phynexis

# Create and configure grid
lsf = phynexis.utils.LevelSetField()
lsf.set_corner(phynexis.utils.Vec3d(0.0, 0.0, 0.0))
lsf.set_spacing(0.1)
lsf.set_dimension(phynexis.utils.Vec3i(11, 11, 11))

print("corner:", lsf.get_corner())
print("spacing:", lsf.get_spacing())
print("dimensions:", lsf.get_dimensions())

# Set phi values
lsf.set_phi(phynexis.utils.Vec3i(5, 5, 5), 1.0)
print("phi at center:", lsf.phi(5, 5, 5))

# Query signed distance
pos = phynexis.utils.Vec3d(0.5, 0.5, 0.5)
print("sd at", pos, ":", lsf.signed_distance(pos))

Output:

corner: Vec3d(0, 0, 0)
spacing: 0.1
dimensions: Vec3i(11, 11, 11)
phi at center: 1.0
sd at Vec3d(0.5, 0.5, 0.5) : -0.5

Unexposed C++ API

• get_phi_array() — Returns FlatArray3D<double> (template type, not directly exposable)