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feat: simple arc self-intersection detection

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linchforever 2 days ago
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37cb3b0ade
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376d67207b
2 changed files with 129 additions and 7 deletions
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  1. 10
      primitive_process/interface/subface/geometry/polyline_fillet.hpp
  2. 124
      primitive_process/src/subface/geometry/polyline_fillet.cpp

10
primitive_process/interface/subface/geometry/polyline_fillet.hpp
View File

@ -19,4 +19,14 @@ void insert_polyline_corner_fillets(const polyline_descriptor_t& profile,
std::vector<double>& out_bulges,
const fillet_config_t& cfg = {});
/**
* @brief 检测并修复 polyline 中负 bulge 圆弧与相邻边的自相交。
* 将自相交段的 bulge 置 0（退化为直线），消除 PMC 歧义区域。
*/
void sanitize_negative_bulge_self_intersections(const std::vector<vector3d>& pts_3d,
std::vector<double>& bulges,
bool is_axis,
bool closed);
} // namespace internal

124
primitive_process/src/subface/geometry/polyline_fillet.cpp
View File

@ -39,7 +39,6 @@ Eigen::Vector2d arc_start_tangent(Eigen::Vector2d A, Eigen::Vector2d B, double b
return rotate2d(d, -sign * theta / 2.0);
}
struct Corner {
bool active = false;
Eigen::Vector2d trim_in; // 圆弧起点
@ -97,7 +96,6 @@ Corner compute_corner(const std::vector<Eigen::Vector2d>& pts,
c.trim_in = pts[i] - trim * T_in;
c.trim_out = pts[i] + trim * T_out;
// bulge 符号：cross>0 → 左转(CCW多边形凸角) → CW弧 → 负 bulge
double fillet_bulge = std::tan(turn_angle / 4.0);
const double cross = T_in.x() * T_out.y() - T_in.y() * T_out.x();
if (cross < 0.0) fillet_bulge = -fillet_bulge;
@ -153,11 +151,19 @@ static double recompute_subarc_bulge(const Eigen::Vector2d& A,
// 规范化：子弧行进方向与原弧一致（CCW 为正，CW 为负）
if (sign_b > 0.0) {
if (delta < 0.0) delta += 2.0 * pi;
if (delta > 2.0 * pi) delta -= 2.0 * pi;
// 强制 delta 落入 (0, 2π]
delta = std::fmod(delta, 2.0 * pi);
if (delta <= 0.0) delta += 2.0 * pi;
} else {
if (delta > 0.0) delta -= 2.0 * pi;
if (delta < -2.0 * pi) delta += 2.0 * pi;
// 强制 delta 落入 [-2π, 0)
delta = std::fmod(delta, 2.0 * pi);
if (delta >= 0.0) delta -= 2.0 * pi;
}
double result = std::tan(delta / 4.0);
if ((b > 0) != (result > 0) && std::abs(result) > 1e-9) {
std::cerr << "[BULGE_SIGN_FLIP] original_b=" << b << " recomputed_bulge=" << result << " delta=" << delta
<< " ang_A=" << ang_A << " ang_B=" << ang_B << "\n";
}
return std::tan(delta / 4.0);
@ -173,8 +179,114 @@ inline void push_point(std::vector<vector3d>& out_points,
out_bulges.push_back(bulge);
}
/**
* @brief 计算点 p 到线段 [a, b] 的最短距离（2D）。
* @details 将参数 t 限制在 [0,1] 以保证只测量到线段本身，而非无限延长线，
* 从而避免把圆弧圆心到相邻线段延长线的误距离当作相交依据。
*/
static double point_to_segment_dist_2d(const Eigen::Vector2d& p, const Eigen::Vector2d& a, const Eigen::Vector2d& b)
{
const Eigen::Vector2d ab = b - a;
const double len2 = ab.squaredNorm();
if (len2 < 1e-24) return (p - a).norm();
const double t = std::clamp((p - a).dot(ab) / len2, 0.0, 1.0);
return (p - (a + t * ab)).norm();
}
} // anonymous namespace
/**
* @brief 检测并修复 polyline 中"负 bulge 圆弧与相邻边发生自相交"的问题。
*
* @details
* 对于负 bulge（CW 弧，在 CCW profile 中表现为内凹弧），若其圆心到相邻线段的
* 距离 < 圆弧半径 R，则该弧与相邻边相交。自相交区域内，PMC 的最近点查询会产生
* 歧义，导致 SDF 符号局部翻转，进而在错误位置生成多余等值面（即图中异常轮廓）。
*
* 修复策略：将发生自相交的段的 bulge 置 0，退化为直线段，并输出诊断日志。
*
* 几何原理（以 CW 弧为例）：
* 弦 AB，半角 half_theta = 2*atan(|b|)
* R = |AB| / (2 * sin(half_theta))
* 圆心 C = midpoint(A,B) + R*cos(half_theta) * perp_right(AB)
* 若 dist(C, 相邻段) < R → 圆与相邻段相交 → 弧自相交
*
* @param pts_3d polyline 顶点（3D，原地读取，不修改）
* @param bulges 各段 bulge 值（若检测到自相交则原地置 0）
* @param is_axis true = XZ 平面（Axis），false = XY 平面（Profile）
* @param closed 是否为闭合多段线
*/
void sanitize_negative_bulge_self_intersections(const std::vector<vector3d>& pts_3d,
std::vector<double>& bulges,
bool is_axis,
bool closed)
{
const auto n = static_cast<uint32_t>(pts_3d.size());
if (n < 2) return;
// 将顶点投影到对应的 2D 工作平面
std::vector<Eigen::Vector2d> pts(n);
for (uint32_t i = 0; i < n; ++i) {
if (is_axis)
pts[i] = {pts_3d[i].z, pts_3d[i].x}; // Axis: XZ 平面 → (Z, X)
else
pts[i] = {pts_3d[i].x, pts_3d[i].y}; // Profile: XY 平面 → (X, Y)
}
const uint32_t seg_count = closed ? n : (n - 1u);
for (uint32_t i = 0; i < seg_count; ++i) {
if (bulges[i] >= 0.0) continue; // 仅检查负 bulge 的内凹弧
const uint32_t i1 = (i + 1u) % n;
const Eigen::Vector2d& A = pts[i];
const Eigen::Vector2d& B = pts[i1];
const double b = bulges[i];
const double chord_len = (B - A).norm();
if (chord_len < 1e-12) continue;
// 计算 CW 弧的圆心与半径
// half_theta = theta/2，其中 theta = 4*atan(|b|) 为弧所对圆心角
const double abs_b = std::abs(b);
const double half_theta = 2.0 * std::atan(abs_b);
const double R = chord_len / (2.0 * std::sin(half_theta));
const Eigen::Vector2d chord_dir = (B - A) / chord_len;
// CW 弧（b < 0）的圆心在弦 AB 的右侧
const Eigen::Vector2d perp_right = {chord_dir.y(), -chord_dir.x()};
const double d_center = R * std::cos(half_theta); // 弦中点到圆心的距离
const Eigen::Vector2d center = 0.5 * (A + B) + d_center * perp_right;
bool self_intersects = false;
// ---- 检测与前一段 [pts[i-1], A] 的自相交 ----
if (closed || i > 0u) {
const uint32_t i0 = (i + n - 1u) % n;
const double dist = point_to_segment_dist_2d(center, pts[i0], A);
if (dist < R * (1.0 - 1e-6)) {
self_intersects = true;
std::cout << "[SANITIZE_ARC] 段[" << i << "] 负bulge圆弧"
<< "（R=" << R << ", bulge=" << b << "）"
<< "圆心到前段距离=" << dist << " < R，"
<< "检测到与前段自相交，bulge → 0（退化直线）\n";
}
}
// ---- 检测与后一段 [B, pts[i+2]] 的自相交 ----
if (!self_intersects && (closed || i + 2u < n)) {
const uint32_t i2 = (i + 2u) % n;
const double dist = point_to_segment_dist_2d(center, B, pts[i2]);
if (dist < R * (1.0 - 1e-6)) {
self_intersects = true;
std::cout << "[SANITIZE_ARC] 段[" << i << "] 负bulge圆弧"
<< "（R=" << R << ", bulge=" << b << "）"
<< "圆心到后段距离=" << dist << " < R，"
<< "检测到与后段自相交，bulge → 0（退化直线）\n";
}
}
if (self_intersects) { bulges[i] = 0.0; }
}
}
void insert_polyline_corner_fillets(const polyline_descriptor_t& desc,
std::vector<vector3d>& out_points,

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