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feat: C/C++ 引擎支持 save_trajectory=0 时直接写 display.txt

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所有引擎（Python/C/C++）在 save_trajectory=0 时行为一致：
- 计算时按 NSTEP 抽帧，只存 sampled 缓冲区
- 直接写入 display.txt（新文本格式）
- 不生成 trajectory.txt

Python 引擎：run_simulation 已支持 ✅
C 引擎：采样缓冲区 + write_display_txt ✅
C++ 引擎：采样缓冲区 + write_display_txt ✅
Fortran 引擎：待完成

compute.py run_engine：save_trajectory=0 时跳过 trajectory.txt 加载
dynamics.py：引擎直接输出 display.txt 时跳过抽帧步骤
This commit is contained in:
Ying-Li Niu
2026-06-12 08:25:27 +08:00
parent 41790a782a
commit dc7bc00616
4 changed files with 195 additions and 51 deletions
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engines/cpp/main.cpp
+84 -17
View File
@@ -43,6 +43,7 @@ struct SimParams {
int damping_force = 0;
double gravity_strength = 1.0;
int driving_force = 0;
int save_trajectory = 1;
};
// ========================================================================
@@ -131,6 +132,11 @@ static std::string json_read_string(const std::string &json, const std::string &
return result;
}
/* 检查 JSON 中是否存在某个 key */
static bool json_has_key(const std::string &json, const std::string &key) {
return json.find("\"" + key + "\"") != std::string::npos;
}
/* 读取 JSON 数组 (如 "G": [0, 0, -9.8]) 到 double[3] */
static void json_read_double3(const std::string &json, const std::string &key, double out[3]) {
auto pos = json.find("\"" + key + "\"");
@@ -165,6 +171,9 @@ static SimParams read_params(const std::string &path) {
p.damping_force = json_read_int(buf, "damping_force");
p.gravity_strength = json_read_double(buf, "gravity_strength");
p.driving_force = json_read_int(buf, "driving_force");
// save_trajectory 默认 1（全量），仅在 JSON 中存在该 key 时覆盖
if (json_has_key(buf, "save_trajectory"))
p.save_trajectory = json_read_int(buf, "save_trajectory");
return p;
}
@@ -681,6 +690,52 @@ static void apply_driving_force(
}
}
// ========================================================================
// display.txt 输出（save_trajectory=0 时使用）
// ========================================================================
static void write_display_txt(
const std::string &path,
const std::vector<double> &x, const std::vector<double> &y,
const std::vector<double> &z, const std::vector<double> &vx,
const std::vector<double> &vy, const std::vector<double> &vz,
int n_steps, int n_atoms,
const SimParams &params, const AtomData &atoms)
{
std::ofstream f(path);
if (!f) die("无法写入 " + path);
std::cout << "[Cpp-engine] 正在写入显示数据…" << std::endl;
double T_total = params.NT * params.DT;
f << "number of frames: " << n_steps << "\n";
f << "number of particles: " << n_atoms << "\n";
f << "DT: " << params.DT << "\n";
f << "NSTEP: " << params.NSTEP << "\n";
f << "method: " << params.method << "\n";
f << "warmup_steps: " << params.warmup_steps << "\n";
f << "dynamic_steps: " << (params.NT - params.warmup_steps) << "\n";
f << "T_total: " << T_total << "\n";
f << "box_a: " << params.box_a << "\n";
f << "driving_force: " << params.driving_force << "\n\n";
f << std::fixed << std::setprecision(6);
for (int t = 0; t < n_steps; t++) {
f << "frame: " << (t + 1) << "\n";
f << "n x y z vx vy vz\n";
for (int i = 0; i < n_atoms; i++) {
int base = t * n_atoms + i;
f << std::setw(3) << atoms.ids[i]
<< std::setw(12) << x[base]
<< std::setw(12) << y[base]
<< std::setw(12) << z[base]
<< std::setw(12) << vx[base]
<< std::setw(12) << vy[base]
<< std::setw(12) << vz[base] << "\n";
}
}
}
// ========================================================================
// JSON 输出
// ========================================================================
@@ -817,12 +872,14 @@ int main(int argc, char **argv) {
// 分配轨迹缓冲区
int record_steps = params.NT - params.warmup_steps;
std::vector<double> traj_x(record_steps * n);
std::vector<double> traj_y(record_steps * n);
std::vector<double> traj_z(record_steps * n);
std::vector<double> traj_vx(record_steps * n);
std::vector<double> traj_vy(record_steps * n);
std::vector<double> traj_vz(record_steps * n);
int nstep_sampling = (params.save_trajectory == 0) ? params.NSTEP : 1;
int buf_steps = (params.save_trajectory == 0) ? (record_steps / nstep_sampling) : record_steps;
std::vector<double> traj_x(buf_steps * n);
std::vector<double> traj_y(buf_steps * n);
std::vector<double> traj_z(buf_steps * n);
std::vector<double> traj_vx(buf_steps * n);
std::vector<double> traj_vy(buf_steps * n);
std::vector<double> traj_vz(buf_steps * n);
// 预热
// 初始时刻 t=0 驱动力（与 Python run_simulation 一致）
@@ -846,6 +903,7 @@ int main(int argc, char **argv) {
// 记录
int _prog_int = record_steps / 100;
if (_prog_int < 1) _prog_int = 1;
int si = 0; // 采样帧索引
for (int s = 0; s < record_steps; s++) {
if (s % _prog_int == 0 && s > 0) {
std::cout << "[Cpp-engine] progress: " << s << "/" << record_steps << std::endl;
@@ -853,14 +911,17 @@ int main(int argc, char **argv) {
double t = (s + params.warmup_steps) * params.DT;
if (params.driving_force)
apply_driving_force(n, x.data(), y.data(), z.data(), vx.data(), vy.data(), vz.data(), t, s, params.DT, drivers);
// 保存当前帧
for (int i = 0; i < n; i++) {
traj_x[s * n + i] = x[i];
traj_y[s * n + i] = y[i];
traj_z[s * n + i] = z[i];
traj_vx[s * n + i] = vx[i];
traj_vy[s * n + i] = vy[i];
traj_vz[s * n + i] = vz[i];
// 保存当前帧（采样模式仅每 NSTEP 步保存一次）
if (s % nstep_sampling == 0) {
for (int i = 0; i < n; i++) {
traj_x[si * n + i] = x[i];
traj_y[si * n + i] = y[i];
traj_z[si * n + i] = z[i];
traj_vx[si * n + i] = vx[i];
traj_vy[si * n + i] = vy[i];
traj_vz[si * n + i] = vz[i];
}
si++;
}
apply_step(params.method, n, x.data(), y.data(), z.data(),
@@ -874,9 +935,15 @@ int main(int argc, char **argv) {
}
// 输出轨迹
std::string out_path = output_dir + "/trajectory.txt";
write_trajectory_json(out_path, traj_x, traj_y, traj_z, traj_vx, traj_vy, traj_vz,
record_steps, n, params, atoms, bonds);
if (params.save_trajectory == 0) {
std::string out_path = output_dir + "/display.txt";
write_display_txt(out_path, traj_x, traj_y, traj_z, traj_vx, traj_vy, traj_vz,
si, n, params, atoms);
} else {
std::string out_path = output_dir + "/trajectory.txt";
write_trajectory_json(out_path, traj_x, traj_y, traj_z, traj_vx, traj_vy, traj_vz,
record_steps, n, params, atoms, bonds);
}
auto t1 = std::chrono::high_resolution_clock::now();
double elapsed = std::chrono::duration<double>(t1 - t0).count();