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use crate::math::{Point, Real, Vector, DIM};
use na::vector;
#[cfg(not(feature = "std"))]
use na::ComplexField;
pub struct QuadraticKernel;
impl QuadraticKernel {
#[inline(always)]
pub fn inv_d(cell_width: Real) -> Real {
4.0 / (cell_width * cell_width)
}
#[inline(always)]
pub fn eval_all(x: Real) -> [Real; 3] {
[
0.5 * (1.5 - x).powi(2),
0.75 - (x - 1.0).powi(2),
0.5 * (x - 0.5).powi(2),
]
}
#[inline(always)]
pub fn eval(x: Real) -> Real {
let x_abs = x.abs();
if x_abs < 0.5 {
3.0 / 4.0 - x_abs.powi(2)
} else if x_abs < 3.0 / 2.0 {
0.5 * (3.0 / 2.0 - x_abs).powi(2)
} else {
0.0
}
}
#[inline(always)]
pub fn eval_derivative(x: Real) -> Real {
let x_abs = x.abs();
if x_abs < 0.5 {
-2.0 * x.signum() * x_abs
} else if x_abs < 3.0 / 2.0 {
-x.signum() * (3.0 / 2.0 - x_abs)
} else {
0.0
}
}
#[inline(always)]
pub fn precompute_weights(
ref_elt_pos_minus_particle_pos: Vector<Real>,
h: Real,
) -> [[Real; 3]; DIM] {
[
Self::eval_all(-ref_elt_pos_minus_particle_pos.x / h),
Self::eval_all(-ref_elt_pos_minus_particle_pos.y / h),
#[cfg(feature = "dim3")]
Self::eval_all(-ref_elt_pos_minus_particle_pos.z / h),
]
}
#[inline(always)]
pub fn stencil_with_dir(elt_pos_minus_particle_pos: Vector<Real>, h: Real) -> Real {
let dpt = -elt_pos_minus_particle_pos / h;
#[cfg(feature = "dim2")]
return Self::eval(dpt.x) * Self::eval(dpt.y);
#[cfg(feature = "dim3")]
return Self::eval(dpt.x) * Self::eval(dpt.y) * Self::eval(dpt.z);
}
#[inline(always)]
pub fn stencil(elt_pos: Point<Real>, particle_pos: Point<Real>, h: Real) -> Real {
Self::stencil_with_dir(elt_pos - particle_pos, h)
}
#[inline(always)]
pub fn stencil_gradient_with_dir(
elt_pos_minus_particle_pos: Vector<Real>,
h: Real,
) -> Vector<Real> {
let inv_h = 1.0 / h;
let dpt = -elt_pos_minus_particle_pos * inv_h;
let val_x = Self::eval(dpt.x);
let val_y = Self::eval(dpt.y);
#[cfg(feature = "dim3")]
let val_z = Self::eval(dpt.z);
#[cfg(feature = "dim2")]
return vector![
inv_h * Self::eval_derivative(dpt.x) * val_y,
inv_h * val_x * Self::eval_derivative(dpt.y)
];
#[cfg(feature = "dim3")]
return vector![
inv_h * Self::eval_derivative(dpt.x) * val_y * val_z,
inv_h * val_x * Self::eval_derivative(dpt.y) * val_z,
inv_h * val_x * val_y * Self::eval_derivative(dpt.z)
];
}
#[inline(always)]
pub fn stencil_gradient(
elt_pos: Point<Real>,
particle_pos: Point<Real>,
h: Real,
) -> Vector<Real> {
Self::stencil_gradient_with_dir(elt_pos - particle_pos, h)
}
}