ale_kinematics_kernel.h

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#ifndef __COMMON_ALE_KINEMATICS_KERNEL_H__
#define __COMMON_ALE_KINEMATICS_KERNEL_H__
 
#include <cmath>
#include <algorithm>
 
#ifndef KINEMATICS_PARAMS_T_DEFINED
#define KINEMATICS_PARAMS_T_DEFINED
typedef struct {
    real cx, cy, cz;
    real vtx, vty, vtz;
    real vax, vay, vaz;
    real px, py, pz;
    real r11, r12, r13;
    real r21, r22, r23;
    real r31, r32, r33;
} kinematics_params_t;
#endif
 
template< typename T >
__global__ void ale_add_kinematics_kernel(const int n, 
                T * __restrict__ wx, 
                T * __restrict__ wy, 
                T * __restrict__ wz,
                const T * __restrict__ x_ref, 
                const T * __restrict__ y_ref, 
                const T * __restrict__ z_ref,
                const T * __restrict__ phi, 
                const T * __restrict__ x, 
                const T * __restrict__ y, 
                const T * __restrict__ z,
                const kinematics_params_t kin_params) {
 
  const int idx = blockIdx.x * blockDim.x + threadIdx.x;
  const int str = blockDim.x * gridDim.x;
  const T one = 1.0;
  const T tol = 1e-6;
 
  for (int i = idx; i < n; i += str) {
    const T p_val = phi[i];
    T v_tan_x, v_tan_y, v_tan_z;
 
    if (fabs(p_val - one) < tol) {
      const T rx = x[i] - kin_params.cx;
      const T ry = y[i] - kin_params.cy;
      const T rz = z[i] - kin_params.cz;
 
      v_tan_x = kin_params.vay * rz - kin_params.vaz * ry;
      v_tan_y = kin_params.vaz * rx - kin_params.vax * rz;
      v_tan_z = kin_params.vax * ry - kin_params.vay * rx;
    } 
    else {
      const T dx_ref = x_ref[i] - kin_params.px;
      const T dy_ref = y_ref[i] - kin_params.py;
      const T dz_ref = z_ref[i] - kin_params.pz;
 
      const T rx_target = kin_params.r11*dx_ref + 
                          kin_params.r12*dy_ref + 
                          kin_params.r13*dz_ref;
 
      const T ry_target = kin_params.r21*dx_ref + 
                          kin_params.r22*dy_ref + 
                          kin_params.r23*dz_ref;
 
      const T rz_target = kin_params.r31*dx_ref + 
                          kin_params.r32*dy_ref + 
                          kin_params.r33*dz_ref;
 
      v_tan_x = kin_params.vay * rz_target - kin_params.vaz * ry_target;
      v_tan_y = kin_params.vaz * rx_target - kin_params.vax * rz_target;
      v_tan_z = kin_params.vax * ry_target - kin_params.vay * rx_target;
    }
 
    wx[i] += (kin_params.vtx + v_tan_x) * p_val;
    wy[i] += (kin_params.vty + v_tan_y) * p_val;
    wz[i] += (kin_params.vtz + v_tan_z) * p_val;
  }
}
 
template <typename T>
__global__ void compute_cheap_dist_kernel(
                T* __restrict__ d,
                const T* __restrict__ x,
                const T* __restrict__ y,
                const T* __restrict__ z,
                const int lx, const int ly, const int lz,
                const int nel, const int local_iters,
                int* __restrict__ nchange)
{
    int e = blockIdx.x * blockDim.x + threadIdx.x;
    if (e >= nel) return;
 
    int iter = 1;
    bool element_changed_ever = false;
    bool changed_local = true;
 
    const int lxy = lx * ly;
    const int lxyz = lx * ly * lz;
    const int e_offset = e * lxyz;
 
    while (changed_local && iter <= local_iters) {
        changed_local = false;
 
        // Loop over GLL nodes in this element
        for (int k = 0; k < lz; ++k) {
            for (int j = 0; j < ly; ++j) {
                for (int i = 0; i < lx; ++i) {
                    int idx1 = i + j * lx + k * lxy + e_offset;
                    T x1 = x[idx1];
                    T y1 = y[idx1];
                    T z1 = z[idx1];
                    T d1 = d[idx1];
 
                    int i0 = max(0, i - 1);
                    int i1 = min(lx - 1, i + 1);
                    int j0 = max(0, j - 1);
                    int j1 = min(ly - 1, j + 1);
                    int k0 = max(0, k - 1);
                    int k1 = min(lz - 1, k + 1);
 
                    // Neighbor check
                    for (int kk = k0; kk <= k1; ++kk) {
                       for (int jj = j0; jj <= j1; ++jj) {
                          for (int ii = i0; ii <= i1; ++ii) {
                             if (ii == i && jj == j && kk == k) continue;
 
                             int idx2 = ii + jj * lx + kk * lxy + e_offset;
                             T x2 = x[idx2];
                             T y2 = y[idx2];
                             T z2 = z[idx2];
                             T d2 = d[idx2];
 
                             T dist = sqrt((x1 - x2)*(x1 - x2) +
                                           (y1 - y2)*(y1 - y2) +
                                           (z1 - z2)*(z1 - z2));
                             T dtmp = d2 + dist;
 
                             if (dtmp < d1) {
                                 d1 = dtmp;
                                 d[idx1] = d1; // Update locally
                                 changed_local = true;
                             }
                          }
                       }
                    }
                }
            }
        }
        if (changed_local) element_changed_ever = true;
        iter++;
    }
 
    if (element_changed_ever) {
        atomicAdd(nchange, 1);
    }
}
 
#endif // __COMMON_ALE_KINEMATICS_KERNEL_H__