Merge newboolean branch into master.

This is for design task T67744, Boolean Redesign.
It adds a choice of solver to the Boolean modifier and the
Intersect (Boolean) and Intersect (Knife) tools.
The 'Fast' choice is the current Bmesh boolean.
The new 'Exact' choice is a more advanced algorithm that supports
overlapping geometry and uses more robust calculations, but is
slower than the Fast choice.
The default with this commit is set to 'Exact'. We can decide before
the 2.91 release whether or not this is the right choice, but this
choice now will get us more testing and feedback on the new code.

1 files changed, 184 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_mpq2.hh b/source/blender/blenlib/BLI_mpq2.hh
new file mode 100644
index 00000000000..6261b50466b
--- /dev/null
+++ b/source/blender/blenlib/BLI_mpq2.hh
@@ -0,0 +1,184 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup bli
+ */
+
+#ifdef WITH_GMP
+
+#  include "BLI_math_mpq.hh"
+#  include "BLI_mpq3.hh"
+
+namespace blender {
+
+struct mpq2 {
+  mpq_class x, y;
+
+  mpq2() = default;
+
+  mpq2(const mpq_class *ptr) : x{ptr[0]}, y{ptr[1]}
+  {
+  }
+
+  mpq2(mpq_class x, mpq_class y) : x(x), y(y)
+  {
+  }
+
+  mpq2(const mpq2 &other) : x(other.x), y(other.y)
+  {
+  }
+
+  mpq2(mpq2 &&other) noexcept : x(std::move(other.x)), y(std::move(other.y))
+  {
+  }
+
+  ~mpq2() = default;
+
+  mpq2 &operator=(const mpq2 &other)
+  {
+    if (this != &other) {
+      x = other.x;
+      y = other.y;
+    }
+    return *this;
+  }
+
+  mpq2 &operator=(mpq2 &&other) noexcept
+  {
+    x = std::move(other.x);
+    y = std::move(other.y);
+    return *this;
+  }
+
+  mpq2(const mpq3 &other) : x(other.x), y(other.y)
+  {
+  }
+
+  operator mpq_class *()
+  {
+    return &x;
+  }
+
+  operator const mpq_class *() const
+  {
+    return &x;
+  }
+
+  /**
+   * Cannot do this exactly in rational arithmetic!
+   * Approximate by going in and out of doubles.
+   */
+  mpq_class length() const
+  {
+    mpq_class lsquared = dot(*this, *this);
+    return mpq_class(sqrt(lsquared.get_d()));
+  }
+
+  friend mpq2 operator+(const mpq2 &a, const mpq2 &b)
+  {
+    return {a.x + b.x, a.y + b.y};
+  }
+
+  friend mpq2 operator-(const mpq2 &a, const mpq2 &b)
+  {
+    return {a.x - b.x, a.y - b.y};
+  }
+
+  friend mpq2 operator*(const mpq2 &a, mpq_class b)
+  {
+    return {a.x * b, a.y * b};
+  }
+
+  friend mpq2 operator/(const mpq2 &a, mpq_class b)
+  {
+    BLI_assert(b != 0);
+    return {a.x / b, a.y / b};
+  }
+
+  friend mpq2 operator*(mpq_class a, const mpq2 &b)
+  {
+    return b * a;
+  }
+
+  friend bool operator==(const mpq2 &a, const mpq2 &b)
+  {
+    return a.x == b.x && a.y == b.y;
+  }
+
+  friend bool operator!=(const mpq2 &a, const mpq2 &b)
+  {
+    return a.x != b.x || a.y != b.y;
+  }
+
+  friend std::ostream &operator<<(std::ostream &stream, const mpq2 &v)
+  {
+    stream << "(" << v.x << ", " << v.y << ")";
+    return stream;
+  }
+
+  static mpq_class dot(const mpq2 &a, const mpq2 &b)
+  {
+    return a.x * b.x + a.y * b.y;
+  }
+
+  static mpq2 interpolate(const mpq2 &a, const mpq2 &b, mpq_class t)
+  {
+    return a * (1 - t) + b * t;
+  }
+
+  static mpq2 abs(const mpq2 &a)
+  {
+    mpq_class abs_x = (a.x >= 0) ? a.x : -a.x;
+    mpq_class abs_y = (a.y >= 0) ? a.y : -a.y;
+    return mpq2(abs_x, abs_y);
+  }
+
+  static mpq_class distance(const mpq2 &a, const mpq2 &b)
+  {
+    return (a - b).length();
+  }
+
+  static mpq_class distance_squared(const mpq2 &a, const mpq2 &b)
+  {
+    return dot(a, b);
+  }
+
+  struct isect_result {
+    enum {
+      LINE_LINE_COLINEAR = -1,
+      LINE_LINE_NONE = 0,
+      LINE_LINE_EXACT = 1,
+      LINE_LINE_CROSS = 2,
+    } kind;
+    mpq_class lambda;
+    mpq_class mu;
+  };
+
+  static isect_result isect_seg_seg(const mpq2 &v1,
+                                    const mpq2 &v2,
+                                    const mpq2 &v3,
+                                    const mpq2 &v4);
+
+  /** There is a sensible use for hashing on exact arithmetic types. */
+  uint64_t hash() const;
+};
+
+}  // namespace blender
+
+#endif /* WITH_GMP */