Implementation of elbow model for the controller position and rotation.

chrome/browser/android/vr_shell/vr_math.h

Index: chrome/browser/android/vr_shell/vr_math.h
diff --git a/chrome/browser/android/vr_shell/vr_math.h b/chrome/browser/android/vr_shell/vr_math.h
index 4b520c293ac81272be87a30f96fdbafa9f656340..97904086fd7ae6af985166f37d2265a6639181e6 100644
--- a/chrome/browser/android/vr_shell/vr_math.h
+++ b/chrome/browser/android/vr_shell/vr_math.h
@@ -42,11 +42,20 @@ typedef struct Colorf {
 } Colorf;
 
 void SetIdentityM(gvr::Mat4f& mat);
+// Left multiply a translation matrix.
 void TranslateM(gvr::Mat4f& tmat, gvr::Mat4f& mat, float x, float y, float z);
+// Left multiply a scale matrix.
 void ScaleM(gvr::Mat4f& tmat, const gvr::Mat4f& mat, float x, float y, float z);
 
+float Clampf(float value, float min, float max);
+float ToDegrees(float radians);
+
+// Spherical Linear Interpolation

[cjgrant, 2017/04/03 19:25:00]

// Spherical linear interpolation.

[acondor_, 2017/04/19 18:44:27]

Done.

+gvr::Vec3f QuatSlerp(gvr::Vec3f start, gvr::Vec3f end, float percent);

[cjgrant, 2017/04/03 19:25:00]

Pass start and end by const&?

[acondor_, 2017/04/19 18:44:27]

Done.

+
 // Util functions that are copied from the treasure_hunt NDK demo in
 // third_party/gvr-andoir-sdk/ folder.
+// Rotation only, ignore translation components.
 gvr::Vec3f MatrixVectorMul(const gvr::Mat4f& m, const gvr::Vec3f& v);
 gvr::Vec3f MatrixVectorRotate(const gvr::Mat4f& m, const gvr::Vec3f& v);
 gvr::Mat4f MatrixMul(const gvr::Mat4f& matrix1, const gvr::Mat4f& matrix2);
@@ -61,16 +70,30 @@ gvr::Vec3f GetTranslation(const gvr::Mat4f& matrix);
 
 gvr::Mat4f QuatToMatrix(const gvr::Quatf& quat);
 
+float VectorLengthSquared(const gvr::Vec3f& vec);
 float VectorLength(const gvr::Vec3f& vec);
 gvr::Vec3f VectorSubtract(const gvr::Vec3f& a, const gvr::Vec3f& b);
+gvr::Vec3f VectorAdd(const gvr::Vec3f& a, const gvr::Vec3f& b);

[cjgrant, 2017/04/03 19:25:00]

If you're adding comments to methods above, certainly do these as well (anything
non-trivial).

[acondor_, 2017/04/19 18:44:27]

Done.

 float VectorDot(const gvr::Vec3f& a, const gvr::Vec3f& b);
+gvr::Vec3f VectorCross(const gvr::Vec3f& a, const gvr::Vec3f& b);
+gvr::Vec3f PointwiseVectorMul(const gvr::Vec3f& a, const gvr::Vec3f& b);
+gvr::Vec3f VectorScalarMul(const gvr::Vec3f& a, float s);
+float VectorAngleDegrees(const gvr::Vec3f& a, const gvr::Vec3f& b);
 
 // Normalize a vector, and return its original length.
 float NormalizeVector(gvr::Vec3f& vec);
 
 void NormalizeQuat(gvr::Quatf& quat);
 
+gvr::Quatf QuatMultiply(const gvr::Quatf& a, const gvr::Quatf& b);
+gvr::Quatf QuatAdd(const gvr::Quatf& a, const gvr::Quatf& b);
+gvr::Quatf QuatScalarMul(const gvr::Quatf& quat, float s);
+gvr::Quatf QuatInverted(const gvr::Quatf& quat);
+float QuatAngleDegrees(const gvr::Quatf& a, const gvr::Quatf& b);
+gvr::Quatf QuatLerp(const gvr::Quatf& a, const gvr::Quatf& b, float t);
+
 gvr::Quatf QuatFromAxisAngle(const gvr::Vec3f& axis, float angle);
+gvr::Quatf FromToRotation(const gvr::Vec3f& from, const gvr::Vec3f& to);

[cjgrant, 2017/04/03 19:25:00]

From the name, I have no idea what this method does.  Maybe FindRotation() would
be better?  It's future explanatory comment will confirm I'm sure. :)

[acondor_, 2017/04/19 18:44:27]

Done.

 
 gvr::Vec3f GetRayPoint(const gvr::Vec3f& rayOrigin,
                        const gvr::Vec3f& rayVector,