Add vector Length function to Quaternion

Bug: 695937
Change-Id: I9355c99f508f61a3d72156c9bca6cbcb4ed18324
Reviewed-on: https://chromium-review.googlesource.com/812445
Reviewed-by: Ian Vollick <vollick@chromium.org>
Commit-Queue: Anna Offenwanger <offenwanger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522289}

CrOS-Libchrome-Original-Commit: c9199d52c916658bec4674a41da856a675eb4945

3 files changed, 20 insertions, 1 deletions

diff --git a/ui/gfx/geometry/quaternion.cc b/ui/gfx/geometry/quaternion.cc
index 9da8f47111..ef7fae06c7 100644
--- a/ui/gfx/geometry/quaternion.cc
+++ b/ui/gfx/geometry/quaternion.cc
@@ -80,8 +80,12 @@ Quaternion Quaternion::Lerp(const Quaternion& q, double t) const {
   return (((1.0 - t) * *this) + (t * q)).Normalized();
 }
 
+double Quaternion::Length() const {
+  return x_ * x_ + y_ * y_ + z_ * z_ + w_ * w_;
+}
+
 Quaternion Quaternion::Normalized() const {
-  double length = x_ * x_ + y_ * y_ + z_ * z_ + w_ * w_;
+  double length = Length();
   if (length < kEpsilon)
     return *this;
   return *this / sqrt(length);
diff --git a/ui/gfx/geometry/quaternion.h b/ui/gfx/geometry/quaternion.h
index f4e124ce52..7f65b796e6 100644
--- a/ui/gfx/geometry/quaternion.h
+++ b/ui/gfx/geometry/quaternion.h
@@ -59,6 +59,8 @@ class GFX_EXPORT Quaternion {
   // and values outside that range will extrapolate beyond in either direction.
   Quaternion Lerp(const Quaternion& q, double t) const;
 
+  double Length() const;
+
   Quaternion Normalized() const;
 
   std::string ToString() const;
diff --git a/ui/gfx/geometry/quaternion_unittest.cc b/ui/gfx/geometry/quaternion_unittest.cc
index 38e192e1d0..5c8fa9b8ae 100644
--- a/ui/gfx/geometry/quaternion_unittest.cc
+++ b/ui/gfx/geometry/quaternion_unittest.cc
@@ -99,6 +99,19 @@ TEST(QuatTest, Scaling) {
   }
 }
 
+TEST(QuatTest, Normalization) {
+  Quaternion q(1, -1, 1, -1);
+  EXPECT_NEAR(q.Length(), 4, kEpsilon);
+
+  q = q.Normalized();
+
+  EXPECT_NEAR(q.Length(), 1, kEpsilon);
+  EXPECT_NEAR(q.x(), 0.5, kEpsilon);
+  EXPECT_NEAR(q.y(), -0.5, kEpsilon);
+  EXPECT_NEAR(q.z(), 0.5, kEpsilon);
+  EXPECT_NEAR(q.w(), -0.5, kEpsilon);
+}
+
 TEST(QuatTest, Lerp) {
   for (size_t i = 1; i < 100; ++i) {
     Quaternion a(0, 0, 0, 0);