`nx_step_geom.nx` source

↩ module page · 102 lines · 4263 B
1// nx_step_geom.nx -- REAL GEOMETRY extraction from a STEP file (cadtwin P3a: structure -> actual coordinates).
2// nx_step_parse gave the assembly tree/BOM; this pulls the model's real 3D geometry: parse every CARTESIAN_POINT
3// entity's coordinate tuple (STEP reals like -10., 0.E+000, 2.5) into a fixed-point point cloud (fx256). That
4// cloud is real model geometry -- feeds the bounding box, and directly into nx_partid (shape descriptor needs
5// only vertices). Composes nx_step_parse. First rung toward face tessellation (planar/B-spline = the next rungs).
6// license_tier: ORIGINAL
7import "nx_step_parse.nx"
8
9const SG_FX: i64 = 256
10
11func sg_isdigit(c: i64) -> i64 { if c >= 48 { if c <= 57 { return 1 } } return 0 }
12// a coordinate token starts with a digit, '-', '+', or '.'
13func sg_is_numstart(c: i64) -> i64 {
  if sg_isdigit(c) == 1 { return 1 }
  if c == 45 { return 1 }
  if c == 43 { return 1 }
  if c == 46 { return 1 }
  return 0
19}
20// advance past non-number chars (spaces, '(', ',') to the next coordinate token
21func sg_skip_to_num(buf: *u8, v0: i64, e: i64) -> i64 {
  var v: i64 = v0
  var go: i64 = 1
  while go == 1 {
      if v >= e { go = 0 } else {
          if sg_is_numstart(buf[v] as i64) == 1 { go = 0 } else { v = v + 1 }
      }
  }
  return v
30}
31// parse a STEP real at p (< e) -> fx256 into out_val; returns index after the number
32func sg_parse_real(buf: *u8, p: i64, e: i64, out_val: *i64) -> i64 {
  var v: i64 = p
  var sign: i64 = 1
  if v < e { if buf[v] == (45 as u8) { sign = 0 - 1; v = v + 1 } else { if buf[v] == (43 as u8) { v = v + 1 } } }
  var intval: i64 = 0
  var g1: i64 = 1
  while g1 == 1 {
      if v < e { let d: i64 = buf[v] as i64; if sg_isdigit(d) == 1 { intval = intval * 10 + (d - 48); v = v + 1 } else { g1 = 0 } } else { g1 = 0 }
  }
  var fx: i64 = intval * SG_FX
  if v < e { if buf[v] == (46 as u8) {                 // fraction
      v = v + 1
      var fnum: i64 = 0
      var fden: i64 = 1
      var g2: i64 = 1
      while g2 == 1 {
          if v < e { let d: i64 = buf[v] as i64; if sg_isdigit(d) == 1 { fnum = fnum * 10 + (d - 48); fden = fden * 10; v = v + 1 } else { g2 = 0 } } else { g2 = 0 }
      }
      if fden > 1 { fx = fx + (fnum * SG_FX) / fden }
  } }
  var exp: i64 = 0
  var esign: i64 = 1
  var hase: i64 = 0
  if v < e { if buf[v] == (69 as u8) { hase = 1; v = v + 1 } }        // 'E'
  if hase == 0 { if v < e { if buf[v] == (101 as u8) { hase = 1; v = v + 1 } } }   // 'e'
  if hase == 1 {
      if v < e { if buf[v] == (45 as u8) { esign = 0 - 1; v = v + 1 } else { if buf[v] == (43 as u8) { v = v + 1 } } }
      var g3: i64 = 1
      while g3 == 1 {
          if v < e { let d: i64 = buf[v] as i64; if sg_isdigit(d) == 1 { exp = exp * 10 + (d - 48); v = v + 1 } else { g3 = 0 } } else { g3 = 0 }
      }
  }
  if exp > 0 {
      var k: i64 = 0
      while k < exp { if esign > 0 { fx = fx * 10 } else { fx = fx / 10 } k = k + 1 }
  }
  out_val[0] = fx * sign
  return v
70}
71// parse the (x,y,z) tuple of CARTESIAN_POINT entity idx into out3 (fx256); 1 if ok
72func sg_point_tuple(st: *i64, idx: i64, out3: *i64) -> i64 {
  let buf: *u8 = st[0] as *u8
  let sp2: *i64 = sys_mmap(16) as *i64
  let ok: i64 = sp_arg_span(st, idx, 1, sp2)           // arg 1 = the coordinate tuple
  if ok == 0 { return 0 }
  let off: i64 = sp2[0]
  let e: i64 = sp2[0] + sp2[1]
  var v: i64 = sg_skip_to_num(buf, off, e)
  v = sg_parse_real(buf, v, e, out3)
  v = sg_skip_to_num(buf, v, e)
  v = sg_parse_real(buf, v, e, ((out3 as i64) + 8) as *i64)
  v = sg_skip_to_num(buf, v, e)
  v = sg_parse_real(buf, v, e, ((out3 as i64) + 16) as *i64)
  return 1
86}
87// extract every CARTESIAN_POINT into out_pts (stride-3 fx256); returns point count (capped at maxp)
88func sg_extract_points(st: *i64, out_pts: *i64, maxp: i64) -> i64 {
  var n: i64 = 0
  let cnt: i64 = st[7]
  var idx: i64 = 0
  while idx < cnt {
      if sp_name_is(st, idx, "CARTESIAN_POINT" as *u8) == 1 {
          if n < maxp {
              sg_point_tuple(st, idx, ((out_pts as i64) + n * 24) as *i64)
              n = n + 1
          }
      }
      idx = idx + 1
  }
  return n
102}
nx_step_geom.nx source

`nx_step_geom.nx` source
