rssn 0.2.9

A comprehensive scientific computing library for Rust, aiming for feature parity with NumPy and SymPy.
Documentation 
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//! Handle-based FFI API for physics MM (Meshless Methods) functions.

use crate::numerical::matrix::Matrix;
use crate::physics::physics_mm;

/// Simulates the dam break scenario and returns the final particle positions as a Matrix handle (Nx2).
#[unsafe(no_mangle)]
pub extern "C" fn rssn_physics_mm_simulate_dam_break() -> *mut Matrix<f64> {
    let results = physics_mm::simulate_dam_break_2d_scenario();

    let rows = results.len();

    if rows == 0 {
        return std::ptr::null_mut();
    }

    let mut flattened = Vec::with_capacity(rows * 2);

    for (x, y) in results {
        flattened.push(x);

        flattened.push(y);
    }

    Box::into_raw(Box::new(Matrix::new(rows, 2, flattened)))
}

/// Creates a new SPH system.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_physics_mm_sph_create(
    h: f64,
    bounds_x: f64,
    bounds_y: f64,
) -> *mut physics_mm::SPHSystem {
    let system = physics_mm::SPHSystem {
        particles: Vec::new(),
        poly6: physics_mm::Poly6Kernel::new(h),
        spiky: physics_mm::SpikyKernel::new(h),
        gravity: physics_mm::Vector2D { x: 0.0, y: -9.8 },
        viscosity: 0.01,
        gas_const: 2000.0,
        rest_density: 1000.0,
        bounds: physics_mm::Vector2D {
            x: bounds_x,
            y: bounds_y,
        },
    };

    Box::into_raw(Box::new(system))
}

/// Frees an SPH system.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_physics_mm_sph_free(system: *mut physics_mm::SPHSystem) {
    unsafe {
        if !system.is_null() {
            let _ = Box::from_raw(system);
        }
    }
}

/// Adds a particle to the SPH system.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_physics_mm_sph_add_particle(
    system: *mut physics_mm::SPHSystem,
    x: f64,
    y: f64,
    vx: f64,
    vy: f64,
    mass: f64,
) {
    unsafe {
        if let Some(sys) = system.as_mut() {
            sys.particles.push(physics_mm::Particle {
                pos: physics_mm::Vector2D { x, y },
                vel: physics_mm::Vector2D { x: vx, y: vy },
                force: physics_mm::Vector2D::default(),
                density: 0.0,
                pressure: 0.0,
                mass,
            });
        }
    }
}

/// Updates the SPH system by one time step.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_physics_mm_sph_update(
    system: *mut physics_mm::SPHSystem,
    dt: f64,
) {
    unsafe {
        if let Some(sys) = system.as_mut() {
            sys.update(dt);
        }
    }
}

/// Returns the number of particles in the SPH system.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub const unsafe extern "C" fn rssn_physics_mm_sph_get_particle_count(
    system: *mut physics_mm::SPHSystem
) -> usize {
    unsafe {
        if let Some(sys) = system.as_ref() {
            sys.particles.len()
        } else {
            0
        }
    }
}

/// Gets particle positions as a Matrix (Nx2).
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_physics_mm_sph_get_positions(
    system: *mut physics_mm::SPHSystem
) -> *mut Matrix<f64> {
    unsafe {
        if let Some(sys) = system.as_ref() {
            let rows = sys.particles.len();

            let mut flattened = Vec::with_capacity(rows * 2);

            for p in &sys.particles {
                flattened.push(p.pos.x);

                flattened.push(p.pos.y);
            }

            Box::into_raw(Box::new(Matrix::new(rows, 2, flattened)))
        } else {
            std::ptr::null_mut()
        }
    }
}