stl_import_mesh.hh

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#include <cstdint>
 
#include "BLI_math_vector_types.hh"
#include "BLI_vector.hh"
#include "BLI_vector_set.hh"
#include "stl_data.hh"
 
struct Mesh;
 
namespace blender::io::stl {
class Triangle {
 public:
  int v1, v2, v3;
  /* Based on an old version of Python's frozen-set hash
   * https://web.archive.org/web/20220520211017/https://stackoverflow.com/questions/20832279/python-frozenset-hashing-algorithm-implementation
   */
  uint64_t hash() const
  {
    uint64_t res = 1927868237UL;
    res *= 4;
    res ^= (v1 ^ (v1 << 16) ^ 89869747UL) * 3644798167UL;
    res ^= (v2 ^ (v2 << 16) ^ 89869747UL) * 3644798167UL;
    res ^= (v3 ^ (v3 << 16) ^ 89869747UL) * 3644798167UL;
    return res * 69069U + 907133923UL;
  }
  friend bool operator==(const Triangle &a, const Triangle &b)
  {
    bool i = (a.v1 == b.v1) && (a.v2 == b.v2) && (a.v3 == b.v3);
    bool j = (a.v1 == b.v1) && (a.v3 == b.v2) && (a.v2 == b.v3);
    bool k = (a.v2 == b.v1) && (a.v1 == b.v2) && (a.v3 == b.v3);
 
    bool l = (a.v2 == b.v1) && (a.v3 == b.v2) && (a.v1 == b.v3);
    bool m = (a.v3 == b.v1) && (a.v1 == b.v2) && (a.v2 == b.v3);
    bool n = (a.v3 == b.v1) && (a.v2 == b.v2) && (a.v1 == b.v3);
 
    return i || j || k || l || m || n;
  }
};
 
class STLMeshHelper {
 private:
  VectorSet<float3> verts_;
  VectorSet<Triangle> tris_;
  Vector<float3> loop_normals_;
  int degenerate_tris_num_;
  int duplicate_tris_num_;
  const bool use_custom_normals_;
 
 public:
  STLMeshHelper(int tris_num, bool use_custom_normals);
 
  /* Creates a new triangle from specified vertex locations,
   * duplicate vertices and triangles are merged.
   */
  bool add_triangle(const PackedTriangle &data);
 
  Mesh *to_mesh();
};
 
}  // namespace blender::io::stl