Expose motion looping correction setting.

include/ozz/animation/offline/motion_extractor.h

@@ -73,14 +73,22 @@ class OZZ_ANIMOFFLINE_DLL MotionExtractor {
     bool x, y, z;         // Extract X, Y, Z components
     Reference reference;  // Extracting reference
     bool bake;            // Bake extracted data to output animation
+    bool loop;  // Distributes begin - end difference to make animation
+                // loopable.
   };
 
-  Settings position_settings = {true, false, true,     // X and Z projection
+  Settings position_settings = {true,
+                                false,
+                                true,                  // X and Z projection
                                 Reference::kSkeleton,  // Reference
-                                true};               // Bake extracted position
-  Settings rotation_settings = {false, true, false,  // Y / Yaw only
+                                true,    // Bake extracted position
+                                false};  // Don't loop position
+  Settings rotation_settings = {false,
+                                true,
+                                false,                 // Y / Yaw only
                                 Reference::kSkeleton,  // Reference
-                                true};  // Bake extracted rotation
+                                true,   // Bake extracted rotation
+                                true};  // Loop rosition
 };
 }  // namespace offline
 }  // namespace animation

samples/motion_extraction/sample_motion_extraction.cc

@@ -147,9 +147,10 @@ class MotionSampleApplication : public ozz::sample::Application {
 
     // Draw motion tracks.
     const float at = controller_.time_ratio();
-    success &= ozz::sample::DrawMotion(_renderer, motion_track_, 0.f, at, 1.f,
-                                       animation_.duration(), transform_,
-                                       ozz::math::Quaternion::identity());
+    const float step = 1.f / (animation_.duration() * 60.f);
+    success &=
+        ozz::sample::DrawMotion(_renderer, motion_track_, 0.f, at, 1.f, step,
+                                transform_, ozz::math::Quaternion::identity());
     return success;
   }
 
@@ -268,51 +269,64 @@ class MotionSampleApplication : public ozz::sample::Application {
       static bool open = true;
       ozz::sample::ImGui::OpenClose oc(_im_gui, "Motion extraction", &open);
       {
-        ozz::sample::ImGui::OpenClose ocp(_im_gui, "Position", nullptr);
-        _im_gui->DoLabel("Components");
-        rebuild |=
-            _im_gui->DoCheckBox("x", &motion_extractor_.position_settings.x);
-        rebuild |=
-            _im_gui->DoCheckBox("y", &motion_extractor_.position_settings.y);
-        rebuild |=
-            _im_gui->DoCheckBox("z", &motion_extractor_.position_settings.z);
-
-        _im_gui->DoLabel("Reference");
-        int ref =
-            static_cast<int>(motion_extractor_.position_settings.reference);
-        rebuild |= _im_gui->DoRadioButton(0, "Identity", &ref);
-        rebuild |= _im_gui->DoRadioButton(1, "Skeleton", &ref);
-        rebuild |= _im_gui->DoRadioButton(2, "First frame", &ref);
-        motion_extractor_.position_settings.reference =
-            static_cast<ozz::animation::offline::MotionExtractor::Reference>(
-                ref);
+        static bool position = true;
+        ozz::sample::ImGui::OpenClose ocp(_im_gui, "Position", &position);
+        {
+          ozz::sample::ImGui::OpenClose ocp(_im_gui, "Components", nullptr);
+          rebuild |=
+              _im_gui->DoCheckBox("x", &motion_extractor_.position_settings.x);
+          rebuild |=
+              _im_gui->DoCheckBox("y", &motion_extractor_.position_settings.y);
+          rebuild |=
+              _im_gui->DoCheckBox("z", &motion_extractor_.position_settings.z);
+        }
+
+        {
+          ozz::sample::ImGui::OpenClose ocp(_im_gui, "Reference", nullptr);
+          int ref =
+              static_cast<int>(motion_extractor_.position_settings.reference);
+          rebuild |= _im_gui->DoRadioButton(0, "Identity", &ref);
+          rebuild |= _im_gui->DoRadioButton(1, "Skeleton", &ref);
+          rebuild |= _im_gui->DoRadioButton(2, "First frame", &ref);
+          motion_extractor_.position_settings.reference =
+              static_cast<ozz::animation::offline::MotionExtractor::Reference>(
+                  ref);
+        }
+        rebuild |= _im_gui->DoCheckBox(
+            "Bake", &motion_extractor_.position_settings.bake);
+        rebuild |= _im_gui->DoCheckBox(
+            "Loop", &motion_extractor_.position_settings.loop);
       }
 
       {
-        ozz::sample::ImGui::OpenClose ocp(_im_gui, "Rotation", nullptr);
-        _im_gui->DoLabel("Components");
-        rebuild |= _im_gui->DoCheckBox("x / pitch",
-                                       &motion_extractor_.rotation_settings.x);
-        rebuild |= _im_gui->DoCheckBox("y / yaw",
-                                       &motion_extractor_.rotation_settings.y);
-        rebuild |= _im_gui->DoCheckBox("z / roll",
-                                       &motion_extractor_.rotation_settings.z);
-
-        _im_gui->DoLabel("Reference");
-        int ref =
-            static_cast<int>(motion_extractor_.rotation_settings.reference);
-        rebuild |= _im_gui->DoRadioButton(0, "Identity", &ref);
-        rebuild |= _im_gui->DoRadioButton(1, "Skeleton", &ref);
-        rebuild |= _im_gui->DoRadioButton(2, "First frame", &ref);
-        motion_extractor_.rotation_settings.reference =
-            static_cast<ozz::animation::offline::MotionExtractor::Reference>(
-                ref);
-      }
+        static bool rotation = true;
+        ozz::sample::ImGui::OpenClose ocp(_im_gui, "Rotation", &rotation);
+        {
+          ozz::sample::ImGui::OpenClose ocp(_im_gui, "Components", nullptr);
+          rebuild |= _im_gui->DoCheckBox(
+              "x / pitch", &motion_extractor_.rotation_settings.x);
+          rebuild |= _im_gui->DoCheckBox(
+              "y / yaw", &motion_extractor_.rotation_settings.y);
+          rebuild |= _im_gui->DoCheckBox(
+              "z / roll", &motion_extractor_.rotation_settings.z);
+        }
 
-      rebuild |= _im_gui->DoCheckBox("Bake position",
-                                     &motion_extractor_.position_settings.bake);
-      rebuild |= _im_gui->DoCheckBox("Bake rotation",
-                                     &motion_extractor_.rotation_settings.bake);
+        {
+          ozz::sample::ImGui::OpenClose ocp(_im_gui, "Reference", nullptr);
+          int ref =
+              static_cast<int>(motion_extractor_.rotation_settings.reference);
+          rebuild |= _im_gui->DoRadioButton(0, "Identity", &ref);
+          rebuild |= _im_gui->DoRadioButton(1, "Skeleton", &ref);
+          rebuild |= _im_gui->DoRadioButton(2, "First frame", &ref);
+          motion_extractor_.rotation_settings.reference =
+              static_cast<ozz::animation::offline::MotionExtractor::Reference>(
+                  ref);
+        }
+        rebuild |= _im_gui->DoCheckBox(
+            "Bake", &motion_extractor_.rotation_settings.bake);
+        rebuild |= _im_gui->DoCheckBox(
+            "Loop", &motion_extractor_.rotation_settings.loop);
+      }
 
       if (rebuild) {
         if (!ExtractMotion()) {

samples/motion_playback/CMakeLists.txt

@@ -3,17 +3,17 @@ add_custom_command(
   DEPENDS $<$<BOOL:${ozz_build_fbx}>:BUILD_DATA>
           "${CMAKE_CURRENT_LIST_DIR}/README.md"
           "${ozz_media_directory}/bin/pab_skeleton.ozz"
-          "${ozz_media_directory}/bin/pab_atlas_no_motion.ozz"
-          "${ozz_media_directory}/bin/pab_atlas_motion_track.ozz"
+          "${ozz_media_directory}/bin/pab_jog_no_motion.ozz"
+          "${ozz_media_directory}/bin/pab_jog_motion_track.ozz"
   OUTPUT  "${CMAKE_CURRENT_BINARY_DIR}/README.md"
           "${CMAKE_CURRENT_BINARY_DIR}/media/skeleton.ozz"
           "${CMAKE_CURRENT_BINARY_DIR}/media/animation.ozz"
           "${CMAKE_CURRENT_BINARY_DIR}/media/motion.ozz"
   COMMAND ${CMAKE_COMMAND} -E make_directory media
   COMMAND ${CMAKE_COMMAND} -E copy "${CMAKE_CURRENT_LIST_DIR}/README.md" .
   COMMAND ${CMAKE_COMMAND} -E copy "${ozz_media_directory}/bin/pab_skeleton.ozz" "./media/skeleton.ozz"
-  COMMAND ${CMAKE_COMMAND} -E copy "${ozz_media_directory}/bin/pab_atlas_no_motion.ozz" "./media/animation.ozz"
-  COMMAND ${CMAKE_COMMAND} -E copy "${ozz_media_directory}/bin/pab_atlas_motion_track.ozz" "./media/motion.ozz"
+  COMMAND ${CMAKE_COMMAND} -E copy "${ozz_media_directory}/bin/pab_jog_no_motion.ozz" "./media/animation.ozz"
+  COMMAND ${CMAKE_COMMAND} -E copy "${ozz_media_directory}/bin/pab_jog_motion_track.ozz" "./media/motion.ozz"
   VERBATIM)
 
 add_executable(sample_motion_playback

src/animation/offline/fbx/CMakeLists.txt

@@ -48,8 +48,8 @@ set(build_configurations
   "/fbx/pab/hand.fbx\;{\"skeleton\":{\"filename\":\"pab_skeleton.ozz\",\"import\":{\"enable\":false}},\"animations\":[{\"clip\":\"curl\",\"filename\":\"pab_curl_additive.ozz\",\"additive\":true,\"additive_reference\":\"skeleton\"},{\"clip\":\"splay\",\"filename\":\"pab_splay_additive.ozz\",\"additive\":true,\"additive_reference\":\"skeleton\"}]}\;output:pab_curl_additive.ozz\;output:pab_splay_additive.ozz\;depend:pab_skeleton.ozz"
 
   # Library data with root motion
-  "/fbx/pab/atlas.fbx\;{\"skeleton\":{\"filename\":\"pab_skeleton.ozz\",\"import\":{\"enable\":false}},\"animations\":[{\"filename\":\"pab_atlas_no_motion.ozz\",\"tracks\":{\"motion\":{\"enable\":true,\"filename\":\"pab_atlas_motion_track.ozz\"}}}]}\;output:pab_atlas_no_motion.ozz\;output:pab_atlas_motion_track.ozz\;depend:pab_skeleton.ozz"
-  "/fbx/pab/locomotions.fbx\;{\"skeleton\":{\"filename\":\"pab_skeleton.ozz\",\"import\":{\"enable\":false}},\"animations\":[{\"filename\":\"pab_*_no_motion.ozz\",\"tracks\":{\"motion\":{\"enable\":true,\"filename\":\"pab_*_motion_track.ozz\"}}}]}\;output:pab_walk_no_motion.ozz\;output:pab_jog_no_motion.ozz\;output:pab_run_no_motion.ozz\;output:pab_walk_motion_track.ozz\;output:pab_jog_motion_track.ozz\;output:pab_run_motion_track.ozz\;depend:pab_skeleton.ozz"
+  "/fbx/pab/atlas.fbx\;{\"skeleton\":{\"filename\":\"pab_skeleton.ozz\",\"import\":{\"enable\":false}},\"animations\":[{\"filename\":\"pab_atlas_no_motion.ozz\",\"tracks\":{\"motion\":{\"enable\":true,\"rotation\":{\"loop\":true},\"filename\":\"pab_atlas_motion_track.ozz\"}}}]}\;output:pab_atlas_no_motion.ozz\;output:pab_atlas_motion_track.ozz\;depend:pab_skeleton.ozz"
+  "/fbx/pab/locomotions.fbx\;{\"skeleton\":{\"filename\":\"pab_skeleton.ozz\",\"import\":{\"enable\":false}},\"animations\":[{\"filename\":\"pab_*_no_motion.ozz\",\"tracks\":{\"motion\":{\"enable\":true,\"rotation\":{\"loop\":true},\"filename\":\"pab_*_motion_track.ozz\"}}}]}\;output:pab_walk_no_motion.ozz\;output:pab_jog_no_motion.ozz\;output:pab_run_no_motion.ozz\;output:pab_walk_motion_track.ozz\;output:pab_jog_motion_track.ozz\;output:pab_run_motion_track.ozz\;depend:pab_skeleton.ozz"
 
   # Robot user channels
   "/fbx/robot.fbx\;\;config_file:${PROJECT_SOURCE_DIR}/samples/user_channel/config.json\;output:robot_skeleton.ozz\;output:robot_animation.ozz\;output:robot_track_grasp.ozz"

src/animation/offline/motion_extractor.cc

@@ -116,37 +116,51 @@ bool MotionExtractor::operator()(const RawAnimation& _input,
   const auto& input_track = _input.tracks[root_joint];
   auto& output_track = _output->tracks[root_joint];
 
-  // Baking reference
+  // Compute extraction reference
   auto ref =
       BuildReference(position_settings.reference, rotation_settings.reference,
                      GetJointLocalRestPose(_skeleton, root_joint), input_track);
 
-  // Copies root position
-  _motion_position->keyframes.clear();
-  for (const auto& joint_key : input_track.translations) {
-    // Takes expected components only.
-    const math::Float3 mask{1.f * position_settings.x,
-                            1.f * position_settings.y,
-                            1.f * position_settings.z};
-    const math::Float3 motion_p = (joint_key.value - ref.translation) * mask;
-    _motion_position->keyframes.push_back(
-        {ozz::animation::offline::RawTrackInterpolation::kLinear,
-         joint_key.time / _input.duration, motion_p});
-  }
-
-  // Copies root rotation
-  _motion_rotation->keyframes.clear();
-  for (const auto& joint_key : input_track.rotations) {
-    // Decompose rotation to take expected components only.
-    const math::Float3 mask{1.f * rotation_settings.y,   // Yaw
-                            1.f * rotation_settings.x,   // Pitch
-                            1.f * rotation_settings.z};  // Roll
-    const auto euler = ToEuler(joint_key.value * Conjugate(ref.rotation));
-    const auto motion_q = math::Quaternion::FromEuler(euler * mask);
-    _motion_rotation->keyframes.push_back(
-        {ozz::animation::offline::RawTrackInterpolation::kLinear,
-         joint_key.time / _input.duration, motion_q});
-  }
+  // Extract root motion
+  // -----------------------------------------------------------------------------
+
+  // Copy function, used to copy aniamtion keyframes to motion keyframes.
+  auto extract = [duration = _input.duration](const auto& _keframes,
+                                              auto _extract, auto& output) {
+    output.clear();
+    for (const auto& joint_key : _keframes) {
+      const auto& motion = _extract(joint_key.value);
+      output.push_back({ozz::animation::offline::RawTrackInterpolation::kLinear,
+                        joint_key.time / duration, motion});
+    }
+  };
+
+  // Copies root position, selecting only expecting components.
+  const math::Float3 position_mask{1.f * position_settings.x,
+                                   1.f * position_settings.y,
+                                   1.f * position_settings.z};
+  extract(
+      input_track.translations,
+      [&mask = position_mask, &ref = ref.translation](const auto& _joint) {
+        return (_joint - ref) * mask;
+      },
+      _motion_position->keyframes);
+
+  // Copies root rotation, selecting only expecting decomposed rotation
+  // components.
+  const math::Float3 rotation_mask{1.f * rotation_settings.y,   // Yaw
+                                   1.f * rotation_settings.x,   // Pitch
+                                   1.f * rotation_settings.z};  // Roll
+  extract(
+      input_track.rotations,
+      [&mask = rotation_mask, &ref = ref.rotation](const auto& _joint) {
+        const auto euler = ToEuler(_joint * Conjugate(ref));
+        return math::Quaternion::FromEuler(euler * mask);
+      },
+      _motion_rotation->keyframes);
+
+  // Bake
+  // -----------------------------------------------------------------------------
 
   // Extract root motion rotation from the animation, aka bake it.
   if (rotation_settings.bake) {
@@ -169,7 +183,44 @@ bool MotionExtractor::operator()(const RawAnimation& _input,
     }
   }
 
+  // Loopify
+  // -----------------------------------------------------------------------------
+  // Distributes the difference between the first and last keyframes all along
+  // animation duration, so tha animation can loop.
+  auto loopify = [](auto& _keyframes, auto _diff, auto _lerp) {
+    if (_keyframes.size() < 2) {
+      return;
+    }
+    const auto delta = _diff(_keyframes.front().value, _keyframes.back().value);
+    for (size_t i = 0; i < _keyframes.size(); i++) {
+      const float alpha = i / (_keyframes.size() - 1.f);
+      auto& value = _keyframes[i].value;
+      value = _lerp(value, delta, alpha);
+    }
+  };
+
+  // Loopify translations
+  if (rotation_settings.loop) {
+    loopify(
+        _motion_rotation->keyframes,
+        [](auto _front, auto _back) { return _front * Conjugate(_back); },
+        [](auto _value, auto _delta, float _alpha) {
+          return NLerp(math::Quaternion::identity(), _delta, _alpha) * _value;
+        });
+  }
+
+  // Loopify rotations
+  if (position_settings.loop) {
+    loopify(
+        _motion_position->keyframes,
+        [](auto _front, auto _back) { return _front - _back; },
+        [](auto _value, auto _delta, float _alpha) {
+          return _delta * _alpha + _value;
+        });
+  }
+
   // Fixup animation translations.
+  // -----------------------------------------------------------------------------
   // When root motion is applied, then root rotation is applied before joint
   // translation. Hence joint's translation should be corrected to support this
   // new composition order.

src/animation/offline/tools/import2ozz.cc

@@ -161,7 +161,7 @@ int OzzImporter::operator()(int _argc, const char** _argv) {
                     << std::endl;
     return EXIT_FAILURE;
   }
-  ozz::log::Log() << "Existing importer successfully." << std::endl;
+  ozz::log::Log() << "Exiting importer successfully." << std::endl;
   return EXIT_SUCCESS;
 }
 

src/animation/offline/tools/import2ozz_config.cc

@@ -341,6 +341,8 @@ bool SanitizeTrackMotionComponent(Json::Value& _root,
   }
 
   MakeDefault(_root, "bake", true, "Bake extracted motion into animation.");
+  MakeDefault(_root, "loop", false,
+              "Distributes begin - end difference to make animation loopable.");
 
   MakeDefault(_root, "raw", false, "Outputs raw track.");
   MakeDefault(_root, "optimize", true, "Activates keyframes optimization.");

src/animation/offline/tools/import2ozz_track.cc

@@ -351,6 +351,7 @@ ozz::animation::offline::MotionExtractor::Settings ProcessMotionTrackSettings(
          "Reference should have been checked during config validation");
 
   settings.bake = _config["bake"].asBool();
+  settings.loop = _config["loop"].asBool();
 
   return settings;
 }

src/animation/offline/tools/reference.json

@@ -75,6 +75,7 @@
             "components" : "xz", //  Components to import, can be any composition of x, y and z.
             "reference" : "skeleton", //  Root motion extraction reference pose, can be identity, skeleton or animation.
             "bake" : true, //  Bake extracted motion into animation.
+            "loop" : false, //  Distributes begin - end difference to make animation loopable.
             "raw" : false, //  Outputs raw track.
             "optimize" : true, //  Activates keyframes optimization.
             "optimization_tolerance" : 0.001 //  Optimization tolerance for the optimized track
@@ -85,6 +86,7 @@
             "components" : "y", //  Components to import, can be any composition of x, y and z.
             "reference" : "skeleton", //  Root motion extraction reference pose, can be identity, skeleton or animation.
             "bake" : true, //  Bake extracted motion into animation.
+            "loop" : false, //  Distributes begin - end difference to make animation loopable.
             "raw" : false, //  Outputs raw track.
             "optimize" : true, //  Activates keyframes optimization.
             "optimization_tolerance" : 0.001 //  Optimization tolerance for the optimized track