1 files changed, 48 insertions, 13 deletions

diff --git a/mojo/examples/sample_app/spinning_cube.cc b/mojo/examples/sample_app/spinning_cube.cc
index 3a09132..7983563 100644
--- a/mojo/examples/sample_app/spinning_cube.cc
+++ b/mojo/examples/sample_app/spinning_cube.cc
@@ -293,8 +293,16 @@ class ESMatrix {
   }
 };
 
+float RotationForTimeDelta(float delta_time) {
+  return delta_time * 40.0f;
 }
 
+float RotationForDragDistance(float drag_distance) {
+  return drag_distance / 5; // Arbitrary damping.
+}
+
+}  // namespace
+
 class SpinningCube::GLState {
  public:
   GLState();
@@ -330,7 +338,9 @@ SpinningCube::SpinningCube()
     : initialized_(false),
       width_(0),
       height_(0),
-      state_(new GLState()) {
+      state_(new GLState()),
+      fling_multiplier_(1.0f),
+      direction_(1) {
   state_->angle_ = 45.0f;
 }
 
@@ -384,23 +394,33 @@ void SpinningCube::OnGLContextLost() {
   state_->OnGLContextLost();
 }
 
-void SpinningCube::Update(float delta_time) {
-  state_->angle_ += ( delta_time * 40.0f );
-  if (state_->angle_ >= 360.0f )
+void SpinningCube::SetFlingMultiplier(float drag_distance,
+                                      float drag_time) {
+  fling_multiplier_ = RotationForDragDistance(drag_distance) /
+      RotationForTimeDelta(drag_time);
+
+}
+
+void SpinningCube::UpdateForTimeDelta(float delta_time) {
+  state_->angle_ += RotationForTimeDelta(delta_time) * fling_multiplier_;
+  if (state_->angle_ >= 360.0f)
     state_->angle_ -= 360.0f;
 
-  float aspect = static_cast<GLfloat>(width_) / static_cast<GLfloat>(height_);
+  // Arbitrary 50-step linear reduction in spin speed.
+  if (fling_multiplier_ > 1.0f) {
+    fling_multiplier_ =
+        std::max(1.0f, fling_multiplier_ - (fling_multiplier_ - 1.0f) / 50);
+  }
 
-  ESMatrix perspective;
-  perspective.LoadIdentity();
-  perspective.Perspective(60.0f, aspect, 1.0f, 20.0f );
+  Update();
+}
 
-  ESMatrix modelview;
-  modelview.LoadIdentity();
-  modelview.Translate(0.0, 0.0, -2.0);
-  modelview.Rotate(state_->angle_, 1.0, 0.0, 1.0);
+void SpinningCube::UpdateForDragDistance(float distance) {
+  state_->angle_ += RotationForDragDistance(distance);
+  if (state_->angle_ >= 360.0f )
+    state_->angle_ -= 360.0f;
 
-  state_->mvp_matrix_.Multiply(&modelview, &perspective);
+  Update();
 }
 
 void SpinningCube::Draw() {
@@ -425,5 +445,20 @@ void SpinningCube::Draw() {
                     0);
 }
 
+void SpinningCube::Update() {
+  float aspect = static_cast<GLfloat>(width_) / static_cast<GLfloat>(height_);
+
+  ESMatrix perspective;
+  perspective.LoadIdentity();
+  perspective.Perspective(60.0f, aspect, 1.0f, 20.0f );
+
+  ESMatrix modelview;
+  modelview.LoadIdentity();
+  modelview.Translate(0.0, 0.0, -2.0);
+  modelview.Rotate(state_->angle_ * direction_, 1.0, 0.0, 1.0);
+
+  state_->mvp_matrix_.Multiply(&modelview, &perspective);
+}
+
 }  // namespace examples
 }  // namespace mojo