From f72f4d96bf007ef8caf98663912c4218535fdf8d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Foucault?= <foucault.clem@gmail.com>
Date: Tue, 11 Jan 2022 14:19:35 +0100
Subject: Deduplicate cross_poly implementation

---
 source/blender/blenlib/BLI_double3.hh           |  6 ----
 source/blender/blenlib/BLI_math_vector.hh       | 25 ++++++++++++++
 source/blender/blenlib/BLI_mpq3.hh              |  2 --
 source/blender/blenlib/intern/math_vec.cc       | 45 -------------------------
 source/blender/blenlib/intern/mesh_intersect.cc |  4 +--
 5 files changed, 27 insertions(+), 55 deletions(-)

diff --git a/source/blender/blenlib/BLI_double3.hh b/source/blender/blenlib/BLI_double3.hh
index cfc39c4ad0a..87b34a6c147 100644
--- a/source/blender/blenlib/BLI_double3.hh
+++ b/source/blender/blenlib/BLI_double3.hh
@@ -27,10 +27,4 @@ namespace blender {
 
 using double3 = vec_base<double, 3>;
 
-namespace math {
-
-double3 cross_poly(Span<double3> poly);
-
-}  // namespace math
-
 }  // namespace blender
diff --git a/source/blender/blenlib/BLI_math_vector.hh b/source/blender/blenlib/BLI_math_vector.hh
index 9b485bf5187..b9b0d1fcbb2 100644
--- a/source/blender/blenlib/BLI_math_vector.hh
+++ b/source/blender/blenlib/BLI_math_vector.hh
@@ -27,6 +27,7 @@
 
 #include "BLI_math_base_safe.h"
 #include "BLI_math_vector.h"
+#include "BLI_span.hh"
 #include "BLI_utildefines.h"
 
 #ifdef WITH_GMP
@@ -317,6 +318,30 @@ inline T cross_high_precision(const T &a, const T &b)
           (float)((double)a.x * b.y - (double)a.y * b.x)};
 }
 
+template<typename T, BLI_ENABLE_IF_FLT_VEC(T), BLI_ENABLE_IF((T::type_length == 3))>
+inline T cross_poly(Span<T> poly)
+{
+  /* Newell's Method. */
+  int nv = static_cast<int>(poly.size());
+  if (nv < 3) {
+    return T(0, 0, 0);
+  }
+  const T *v_prev = &poly[nv - 1];
+  const T *v_curr = &poly[0];
+  T n(0, 0, 0);
+  for (int i = 0; i < nv;) {
+    n[0] = n[0] + ((*v_prev)[1] - (*v_curr)[1]) * ((*v_prev)[2] + (*v_curr)[2]);
+    n[1] = n[1] + ((*v_prev)[2] - (*v_curr)[2]) * ((*v_prev)[0] + (*v_curr)[0]);
+    n[2] = n[2] + ((*v_prev)[0] - (*v_curr)[0]) * ((*v_prev)[1] + (*v_curr)[1]);
+    v_prev = v_curr;
+    ++i;
+    if (i < nv) {
+      v_curr = &poly[i];
+    }
+  }
+  return n;
+}
+
 template<typename T, BLI_ENABLE_IF_FLT_VEC(T)> inline T interpolate(const T &a, const T &b, bT t)
 {
   return a * (1 - t) + b * t;
diff --git a/source/blender/blenlib/BLI_mpq3.hh b/source/blender/blenlib/BLI_mpq3.hh
index 985222cb706..4bc9564a502 100644
--- a/source/blender/blenlib/BLI_mpq3.hh
+++ b/source/blender/blenlib/BLI_mpq3.hh
@@ -35,8 +35,6 @@ using mpq3 = vec_base<mpq_class, 3>;
 
 namespace math {
 
-mpq3 cross_poly(Span<mpq3> poly);
-
 uint64_t hash_mpq_class(const mpq_class &value);
 
 template<> inline uint64_t vector_hash(const mpq3 &vec)
diff --git a/source/blender/blenlib/intern/math_vec.cc b/source/blender/blenlib/intern/math_vec.cc
index e1d3707f1e8..a4c825327d2 100644
--- a/source/blender/blenlib/intern/math_vec.cc
+++ b/source/blender/blenlib/intern/math_vec.cc
@@ -122,52 +122,7 @@ isect_result<mpq2> isect_seg_seg(const mpq2 &v1, const mpq2 &v2, const mpq2 &v3,
 }
 #endif
 
-double3 cross_poly(Span<double3> poly)
-{
-  /* Newell's Method. */
-  int nv = static_cast<int>(poly.size());
-  if (nv < 3) {
-    return double3(0, 0, 0);
-  }
-  const double3 *v_prev = &poly[nv - 1];
-  const double3 *v_curr = &poly[0];
-  double3 n(0, 0, 0);
-  for (int i = 0; i < nv;) {
-    n[0] = n[0] + ((*v_prev)[1] - (*v_curr)[1]) * ((*v_prev)[2] + (*v_curr)[2]);
-    n[1] = n[1] + ((*v_prev)[2] - (*v_curr)[2]) * ((*v_prev)[0] + (*v_curr)[0]);
-    n[2] = n[2] + ((*v_prev)[0] - (*v_curr)[0]) * ((*v_prev)[1] + (*v_curr)[1]);
-    v_prev = v_curr;
-    ++i;
-    if (i < nv) {
-      v_curr = &poly[i];
-    }
-  }
-  return n;
-}
-
 #ifdef WITH_GMP
-mpq3 cross_poly(Span<mpq3> poly)
-{
-  /* Newell's Method. */
-  int nv = static_cast<int>(poly.size());
-  if (nv < 3) {
-    return mpq3(0);
-  }
-  const mpq3 *v_prev = &poly[nv - 1];
-  const mpq3 *v_curr = &poly[0];
-  mpq3 n(0);
-  for (int i = 0; i < nv;) {
-    n[0] = n[0] + ((*v_prev)[1] - (*v_curr)[1]) * ((*v_prev)[2] + (*v_curr)[2]);
-    n[1] = n[1] + ((*v_prev)[2] - (*v_curr)[2]) * ((*v_prev)[0] + (*v_curr)[0]);
-    n[2] = n[2] + ((*v_prev)[0] - (*v_curr)[0]) * ((*v_prev)[1] + (*v_curr)[1]);
-    v_prev = v_curr;
-    ++i;
-    if (i < nv) {
-      v_curr = &poly[i];
-    }
-  }
-  return n;
-}
 
 uint64_t hash_mpq_class(const mpq_class &value)
 {
diff --git a/source/blender/blenlib/intern/mesh_intersect.cc b/source/blender/blenlib/intern/mesh_intersect.cc
index 2485c222ee6..6f559311fb0 100644
--- a/source/blender/blenlib/intern/mesh_intersect.cc
+++ b/source/blender/blenlib/intern/mesh_intersect.cc
@@ -198,7 +198,7 @@ void Face::populate_plane(bool need_exact)
       for (int i : index_range()) {
         co[i] = vert[i]->co_exact;
       }
-      normal_exact = math::cross_poly(co);
+      normal_exact = math::cross_poly(co.as_span());
     }
     else {
       mpq3 tr02 = vert[0]->co_exact - vert[2]->co_exact;
@@ -215,7 +215,7 @@ void Face::populate_plane(bool need_exact)
       for (int i : index_range()) {
         co[i] = vert[i]->co;
       }
-      normal = math::cross_poly(co);
+      normal = math::cross_poly(co.as_span());
     }
     else {
       double3 tr02 = vert[0]->co - vert[2]->co;
-- 
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