Add Vector3dF::GetNormalized

This is a common operation that can fail if the vector is too
short.

Bug: 718004
Change-Id: I8b379249e3d4b2bc8c500d756899064d8fbb74a5
Reviewed-on: https://chromium-review.googlesource.com/535113
Commit-Queue: Ian Vollick <vollick@chromium.org>
Reviewed-by: Yash Malik <ymalik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#479278}

CrOS-Libchrome-Original-Commit: bed672a16779591caaaa3f9f3f1814dbfc48fc16

3 files changed, 40 insertions, 0 deletions

diff --git a/ui/gfx/geometry/vector3d_f.cc b/ui/gfx/geometry/vector3d_f.cc
index a834047215..c516172eba 100644
--- a/ui/gfx/geometry/vector3d_f.cc
+++ b/ui/gfx/geometry/vector3d_f.cc
@@ -10,6 +10,7 @@
 
 namespace {
 const float kRadiansToDegrees = 180.0f / 3.14159265f;
+const double kEpsilon = 1.0e-6;
 }
 
 namespace gfx {
@@ -61,6 +62,15 @@ void Vector3dF::Cross(const Vector3dF& other) {
   z_ = z;
 }
 
+bool Vector3dF::GetNormalized(Vector3dF* out) const {
+  double length_squared = LengthSquared();
+  *out = *this;
+  if (length_squared < kEpsilon * kEpsilon)
+    return false;
+  out->Scale(1 / sqrt(length_squared));
+  return true;
+}
+
 float DotProduct(const Vector3dF& lhs, const Vector3dF& rhs) {
   return lhs.x() * rhs.x() + lhs.y() * rhs.y() + lhs.z() * rhs.z();
 }
diff --git a/ui/gfx/geometry/vector3d_f.h b/ui/gfx/geometry/vector3d_f.h
index 61e6173060..0bb42b4758 100644
--- a/ui/gfx/geometry/vector3d_f.h
+++ b/ui/gfx/geometry/vector3d_f.h
@@ -71,6 +71,10 @@ class GFX_EXPORT Vector3dF {
   // Take the cross product of this vector with |other| and become the result.
   void Cross(const Vector3dF& other);
 
+  // |out| is assigned a unit-length vector in the direction of |this| iff
+  // this function returns true. It can return false if |this| is too short.
+  bool GetNormalized(Vector3dF* out) const;
+
   std::string ToString() const;
 
  private:
diff --git a/ui/gfx/geometry/vector3d_unittest.cc b/ui/gfx/geometry/vector3d_unittest.cc
index 1aaebb6a4d..12ee757346 100644
--- a/ui/gfx/geometry/vector3d_unittest.cc
+++ b/ui/gfx/geometry/vector3d_unittest.cc
@@ -318,4 +318,30 @@ TEST(Vector3dTest, ClockwiseAngleBetweenVectorsInDegress) {
   }
 }
 
+TEST(Vector3dTest, GetNormalized) {
+  const struct {
+    bool expected;
+    gfx::Vector3dF v;
+    gfx::Vector3dF normalized;
+  } tests[] = {
+      {false, gfx::Vector3dF(0, 0, 0), gfx::Vector3dF(0, 0, 0)},
+      {false,
+       gfx::Vector3dF(std::numeric_limits<float>::min(),
+                      std::numeric_limits<float>::min(),
+                      std::numeric_limits<float>::min()),
+       gfx::Vector3dF(std::numeric_limits<float>::min(),
+                      std::numeric_limits<float>::min(),
+                      std::numeric_limits<float>::min())},
+      {true, gfx::Vector3dF(1, 0, 0), gfx::Vector3dF(1, 0, 0)},
+      {true, gfx::Vector3dF(std::numeric_limits<float>::max(), 0, 0),
+       gfx::Vector3dF(1, 0, 0)},
+  };
+
+  for (size_t i = 0; i < arraysize(tests); ++i) {
+    gfx::Vector3dF n;
+    EXPECT_EQ(tests[i].expected, tests[i].v.GetNormalized(&n));
+    EXPECT_EQ(tests[i].normalized.ToString(), n.ToString());
+  }
+}
+
 }  // namespace gfx