[Vision Glass] Beam extends all the way to the pointer

It is easy to get lost while using the Vision Glass because the
controllers are not drawn in the 3D world and the narrow
field of view means that the beam is not always visible to the user.

This change extends the beam so it reaches all the way to
the pointer, making the UI more understandable.

app/src/visionglass/cpp/DeviceDelegateVisionGlass.cpp

@@ -234,6 +234,14 @@ DeviceDelegateVisionGlass::GetControllerModelName(const int32_t) const {
   return "Vision Glass";
 }
 
+void
+DeviceDelegateVisionGlass::SetHitDistance(const float distance) {
+  // Scale the beam so it reaches all the way to the pointer.
+  auto beamTransform = vrb::Matrix::Identity();
+  beamTransform.ScaleInPlace(vrb::Vector(1.0, 1.0, distance));
+  m.controller->SetBeamTransform(kControllerIndex, beamTransform);
+}
+
 void
 DeviceDelegateVisionGlass::ProcessEvents() {}
 

app/src/visionglass/cpp/DeviceDelegateVisionGlass.h

@@ -42,6 +42,7 @@ class DeviceDelegateVisionGlass : public DeviceDelegate {
   void BindEye(const device::Eye) override;
   void EndFrame(const FrameEndMode aMode) override;
   bool IsControllerLightEnabled() const override;
+  void SetHitDistance(const float) override;
   // DeviceDelegateVisionGlass interface
   void InitializeJava(JNIEnv* aEnv, jobject aActivity);
   void ShutdownJava();