Initial commit

3rdparty/ozz-animation/samples/look_at/CMakeLists.txt

@@ -0,0 +1,55 @@
+
+add_custom_command(
+  DEPENDS $<$<BOOL:${ozz_build_fbx}>:BUILD_DATA>
+          $<$<BOOL:${ozz_build_fbx}>:BUILD_DATA_SAMPLE>
+          "${CMAKE_CURRENT_LIST_DIR}/README.md"
+          "${ozz_media_directory}/bin/pab_skeleton.ozz"
+          "${ozz_media_directory}/bin/pab_crossarms.ozz"
+          "${ozz_media_directory}/bin/arnaud_mesh.ozz"
+  OUTPUT  "${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/mesh.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_crossarms.ozz" "./media/animation.ozz"
+  COMMAND ${CMAKE_COMMAND} -E copy "${ozz_media_directory}/bin/arnaud_mesh.ozz" "./media/mesh.ozz"
+  VERBATIM)
+
+add_executable(sample_look_at
+  sample_look_at.cc
+  "${CMAKE_CURRENT_BINARY_DIR}/README.md"
+  "${CMAKE_CURRENT_BINARY_DIR}/media/skeleton.ozz"
+  "${CMAKE_CURRENT_BINARY_DIR}/media/animation.ozz"
+  "${CMAKE_CURRENT_BINARY_DIR}/media/mesh.ozz")
+target_link_libraries(sample_look_at
+  sample_framework)
+
+set_target_properties(sample_look_at
+  PROPERTIES FOLDER "samples")
+
+if(EMSCRIPTEN)
+  # Resource files are embedded to the output file with emscripten
+  set_target_properties(sample_look_at
+    PROPERTIES LINK_FLAGS "--embed-file media --embed-file README.md --memory-init-file 0")
+
+  install(FILES
+    ${CMAKE_CURRENT_BINARY_DIR}/sample_look_at.html
+    ${CMAKE_CURRENT_BINARY_DIR}/sample_look_at.js
+    ${CMAKE_CURRENT_BINARY_DIR}/sample_look_at.wasm
+    DESTINATION bin/samples/look_at)
+else()
+  install(TARGETS sample_look_at DESTINATION bin/samples/look_at)
+  install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/media DESTINATION bin/samples/look_at)
+  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/README.md DESTINATION bin/samples/look_at)
+endif(EMSCRIPTEN)
+
+add_test(NAME sample_look_at COMMAND sample_look_at "--max_idle_loops=${ozz_sample_testing_loops}" $<$<BOOL:${ozz_run_tests_headless}>:--norender>)
+add_test(NAME sample_look_at_path1 COMMAND sample_look_at "--skeleton=media/skeleton.ozz" "--animation=media/animation.ozz" "--mesh=media/mesh.ozz" "--max_idle_loops=${ozz_sample_testing_loops}" $<$<BOOL:${ozz_run_tests_headless}>:--norender>)
+add_test(NAME sample_look_at_invalid_skeleton_path COMMAND sample_look_at "--skeleton=media/bad_skeleton.ozz" $<$<BOOL:${ozz_run_tests_headless}>:--norender>)
+set_tests_properties(sample_look_at_invalid_skeleton_path PROPERTIES WILL_FAIL true)
+add_test(NAME sample_look_at_invalid_animation_path COMMAND sample_look_at "--animation=media/bad_animation.ozz" $<$<BOOL:${ozz_run_tests_headless}>:--norender>)
+set_tests_properties(sample_look_at_invalid_animation_path PROPERTIES WILL_FAIL true)
+add_test(NAME sample_look_at_invalid_mesh_path COMMAND sample_look_at "--mesh=media/bad_mesh.ozz" $<$<BOOL:${ozz_run_tests_headless}>:--norender>)
+set_tests_properties(sample_look_at_invalid_mesh_path PROPERTIES WILL_FAIL true)

3rdparty/ozz-animation/samples/look_at/README.md

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+# Ozz-animation sample: Look-at
+
+## Description
+
+Procedural look-at objective is to orientate character head in a direction (at a target position), without using any animation data. This comes as a correction on (some) joint(s) rotation, on top of current animation. The character could still use animation as a base look-at depending on target position, and use the procedural correction for the final/precise adjustment.
+
+## Concept
+
+The sample relies on ozz::animation::IKAimJob which allows a single joint to aim at a targeted position. It extends the basic IKAimJob usage, by iteratively applying IK to head's ancestor joints, allowing to spread the rotation over more joints for a more realistic result. ozz::animation::IKAimJob::offset member (offset position from the joint in local-space) is a key component to achieve this result. It's used at first to tune eyes position compared to the head joint. During later iterations (for head ancestors), offset becomes even more relevant as the distance to the joint increases.
+
+This same concept can be applied to aim a weapon at a precise target.
+
+## Sample usage
+
+The sample allows to move target position or change its animation settings. If also exposes important setup aspects of the IK chain:
+- Chain length: Number of joints (from the predefined hierarchy) that are corrected by IK.
+- Joint weight: Weight given to IK for each joint of the chain (except for the last joint which is 1). This directly affect correction spreading.
+- Chain weight: Weight given to the whole look-at process, allowing bending in and out.
+Debug settings are exposed to help understanding:
+- Displaying character forward vector is interesting to confirm algorithm precision.
+- Displaying joints part of the look-at chain helps understand how weight and correction are spread.
+
+## Implementation
+
+1. At initialization time:
+   1. Loads skeleton, animation and mesh. See "playback" sample for more details.
+   2. Locates head joint and some of its ancestors, searching them by name.
+2. At run time:
+   1. Updates base animation and skeleton joints model-space matrices. See "playback" sample for more details.
+   2. Iteratively updates from the first joint (closer to the head) to the last (the further ancestor, closer to the pelvis). For the first joint, aim IK is applied with the global forward and offset, so the forward vector aligns in direction of the target.
+   3. If a weight lower that 1 is provided to the first joint, then it will not fully align to the target. In this case further joint will need to be updated:
+      1. Rotates forward and offset position based on the result of the previous joint IK.
+      2. Brings forward and offset back in next joint local-space.
+      3. Applies IKAimJob.
+   4. Aim is iteratively applied up to the last selected joint of the hierarchy. A weight of 1 is given to the last joint so we can guarantee target is reached.
+   5. Updates model-space transforms. Note that they don't need to be updated between each pass, as joints are ordered from child to parent.

3rdparty/ozz-animation/samples/look_at/sample_look_at.cc

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+//----------------------------------------------------------------------------//
+//                                                                            //
+// ozz-animation is hosted at http://github.com/guillaumeblanc/ozz-animation  //
+// and distributed under the MIT License (MIT).                               //
+//                                                                            //
+// Copyright (c) Guillaume Blanc                                              //
+//                                                                            //
+// Permission is hereby granted, free of charge, to any person obtaining a    //
+// copy of this software and associated documentation files (the "Software"), //
+// to deal in the Software without restriction, including without limitation  //
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,   //
+// and/or sell copies of the Software, and to permit persons to whom the      //
+// Software is furnished to do so, subject to the following conditions:       //
+//                                                                            //
+// The above copyright notice and this permission notice shall be included in //
+// all copies or substantial portions of the Software.                        //
+//                                                                            //
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR //
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,   //
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL    //
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER //
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING    //
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER        //
+// DEALINGS IN THE SOFTWARE.                                                  //
+//                                                                            //
+//----------------------------------------------------------------------------//
+
+#include "ozz/animation/runtime/animation.h"
+#include "ozz/animation/runtime/ik_aim_job.h"
+#include "ozz/animation/runtime/local_to_model_job.h"
+#include "ozz/animation/runtime/sampling_job.h"
+#include "ozz/animation/runtime/skeleton.h"
+
+#include "ozz/base/log.h"
+
+#include "ozz/base/maths/box.h"
+#include "ozz/base/maths/simd_math.h"
+#include "ozz/base/maths/simd_quaternion.h"
+#include "ozz/base/maths/soa_transform.h"
+#include "ozz/base/maths/vec_float.h"
+
+#include "ozz/options/options.h"
+
+#include "framework/application.h"
+#include "framework/imgui.h"
+#include "framework/mesh.h"
+#include "framework/renderer.h"
+#include "framework/utils.h"
+
+// Skeleton archive can be specified as an option.
+OZZ_OPTIONS_DECLARE_STRING(skeleton,
+                           "Path to the skeleton (ozz archive format).",
+                           "media/skeleton.ozz", false)
+
+// Animation archive can be specified as an option.
+OZZ_OPTIONS_DECLARE_STRING(animation,
+                           "Path to the animation (ozz archive format).",
+                           "media/animation.ozz", false)
+
+// Mesh archive can be specified as an option.
+OZZ_OPTIONS_DECLARE_STRING(mesh,
+                           "Path to the skinned mesh (ozz archive format).",
+                           "media/mesh.ozz", false)
+
+// Defines IK chain joint names.
+// Joints must be from the same hierarchy (all ancestors of the first joint
+// listed) and ordered from child to parent.
+const char* kJointNames[] = {"Head", "Spine3", "Spine2", "Spine1"};
+const size_t kMaxChainLength = OZZ_ARRAY_SIZE(kJointNames);
+
+// Forward vector in head local-space.
+const ozz::math::SimdFloat4 kHeadForward = ozz::math::simd_float4::y_axis();
+
+// Defines Up vectors for each joint. This is skeleton/rig dependant.
+const ozz::math::SimdFloat4 kJointUpVectors[] = {
+    ozz::math::simd_float4::x_axis(), ozz::math::simd_float4::x_axis(),
+    ozz::math::simd_float4::x_axis(), ozz::math::simd_float4::x_axis()};
+static_assert(OZZ_ARRAY_SIZE(kJointUpVectors) == kMaxChainLength,
+              "Array size mismatch.");
+
+class LookAtSampleApplication : public ozz::sample::Application {
+ public:
+  LookAtSampleApplication()
+      : target_offset_(.2f, 1.5f, -.3f),
+        target_extent_(1.f),
+        eyes_offset_(.07f, .1f, 0.f),
+        enable_ik_(true),
+        chain_length_(kMaxChainLength),
+        joint_weight_(.5f),
+        chain_weight_(1.f),
+        show_skin_(true),
+        show_joints_(false),
+        show_target_(true),
+        show_eyes_offset_(false),
+        show_forward_(false) {}
+
+ protected:
+  // Updates current animation time and skeleton pose.
+  virtual bool OnUpdate(float _dt, float _time) {
+    // Animates target position.
+    MoveTarget(_time);
+
+    // Updates current animation time.
+    controller_.Update(animation_, _dt);
+
+    // Samples optimized animation at t = animation_time_.
+    ozz::animation::SamplingJob sampling_job;
+    sampling_job.animation = &animation_;
+    sampling_job.cache = &cache_;
+    sampling_job.ratio = controller_.time_ratio();
+    sampling_job.output = make_span(locals_);
+    if (!sampling_job.Run()) {
+      return false;
+    }
+
+    // Converts from local-space to model-space matrices.
+    ozz::animation::LocalToModelJob ltm_job;
+    ltm_job.skeleton = &skeleton_;
+    ltm_job.input = make_span(locals_);
+    ltm_job.output = make_span(models_);
+    if (!ltm_job.Run()) {
+      return false;
+    }
+
+    // Early out if IK is disabled.
+    if (!enable_ik_) {
+      return true;
+    }
+
+    // IK aim job setup.
+    ozz::animation::IKAimJob ik_job;
+
+    // Pole vector and target position are constant for the whole algorithm, in
+    // model-space.
+    ik_job.pole_vector = ozz::math::simd_float4::y_axis();
+    ik_job.target = ozz::math::simd_float4::Load3PtrU(&target_.x);
+
+    // The same quaternion will be used each time the job is run.
+    ozz::math::SimdQuaternion correction;
+    ik_job.joint_correction = &correction;
+
+    // The algorithm iteratively updates from the first joint (closer to the
+    // head) to the last (the further ancestor, closer to the pelvis). Joints
+    // order is already validated. For the first joint, aim IK is applied with
+    // the global forward and offset, so the forward vector aligns in direction
+    // of the target. If a weight lower that 1 is provided to the first joint,
+    // then it will not fully align to the target. In this case further joint
+    // will need to be updated. For the remaining joints, forward vector and
+    // offset position are computed in each joint local-space, before IK is
+    // applied:
+    // 1. Rotates forward and offset position based on the result of the
+    // previous joint IK.
+    // 2. Brings forward and offset back in joint local-space.
+    // Aim is iteratively applied up to the last selected joint of the
+    // hierarchy. A weight of 1 is given to the last joint so we can guarantee
+    // target is reached. Note that model-space transform of each joint doesn't
+    // need to be updated between each pass, as joints are ordered from child to
+    // parent.
+    int previous_joint = ozz::animation::Skeleton::kNoParent;
+    for (int i = 0, joint = joints_chain_[0]; i < chain_length_;
+         ++i, previous_joint = joint, joint = joints_chain_[i]) {
+      // Setups the model-space matrix of the joint being processed by IK.
+      ik_job.joint = &models_[joint];
+
+      // Setups joint local-space up vector.
+      ik_job.up = kJointUpVectors[i];
+
+      // Setups weights of IK job.
+      // the last joint being processed needs a full weight (1.f) to ensure
+      // target is reached.
+      const bool last = i == chain_length_ - 1;
+      ik_job.weight = chain_weight_ * (last ? 1.f : joint_weight_);
+
+      // Setup offset and forward vector for the current joint being processed.
+      if (i == 0) {
+        // First joint, uses global forward and offset.
+        ik_job.offset = ozz::math::simd_float4::Load3PtrU(&eyes_offset_.x);
+        ik_job.forward = kHeadForward;
+      } else {
+        // Applies previous correction to "forward" and "offset", before
+        // bringing them to model-space (_ms).
+        const ozz::math::SimdFloat4 corrected_forward_ms =
+            TransformVector(models_[previous_joint],
+                            TransformVector(correction, ik_job.forward));
+        const ozz::math::SimdFloat4 corrected_offset_ms =
+            TransformPoint(models_[previous_joint],
+                           TransformVector(correction, ik_job.offset));
+
+        // Brings "forward" and "offset" to joint local-space
+        const ozz::math::Float4x4 inv_joint = Invert(models_[joint]);
+        ik_job.forward = TransformVector(inv_joint, corrected_forward_ms);
+        ik_job.offset = TransformPoint(inv_joint, corrected_offset_ms);
+      }
+
+      // Runs IK aim job.
+      if (!ik_job.Run()) {
+        return false;
+      }
+
+      // Apply IK quaternion to its respective local-space transforms.
+      ozz::sample::MultiplySoATransformQuaternion(joint, correction,
+                                                  make_span(locals_));
+    }
+
+    // Skeleton model-space matrices need to be updated again. This re-uses the
+    // already setup job, but limits the update to childs of the last joint (the
+    // parent-iest of the chain).
+    ltm_job.from = previous_joint;
+    if (!ltm_job.Run()) {
+      return false;
+    }
+
+    return true;
+  }
+
+  // Sample arbitrary target animation implementation.
+  bool MoveTarget(float _time) {
+    const ozz::math::Float3 animated_target(std::sin(_time * .5f),
+                                            std::cos(_time * .25f),
+                                            std::cos(_time) * .5f + .5f);
+    target_ = target_offset_ + animated_target * target_extent_;
+    return true;
+  }
+
+  // Samples animation, transforms to model space and renders.
+  virtual bool OnDisplay(ozz::sample::Renderer* _renderer) {
+    bool success = true;
+    const ozz::math::Float4x4 identity = ozz::math::Float4x4::identity();
+    const float kAxeScale = .1f;
+    const ozz::math::Float4x4 kAxesScale =
+        ozz::math::Float4x4::Scaling(ozz::math::simd_float4::Load1(kAxeScale));
+
+    // Renders character.
+    if (show_skin_) {
+      // Builds skinning matrices.
+      // The mesh might not use (aka be skinned by) all skeleton joints. We
+      // use the joint remapping table (available from the mesh object) to
+      // reorder model-space matrices and build skinning ones.
+      for (size_t m = 0; m < meshes_.size(); ++m) {
+        const ozz::sample::Mesh& mesh = meshes_[m];
+        for (size_t i = 0; i < mesh.joint_remaps.size(); ++i) {
+          skinning_matrices_[i] =
+              models_[mesh.joint_remaps[i]] * mesh.inverse_bind_poses[i];
+        }
+
+        success &= _renderer->DrawSkinnedMesh(
+            mesh, make_span(skinning_matrices_), identity);
+      }
+    } else {
+      // Renders skeleton only.
+      success &=
+          _renderer->DrawPosture(skeleton_, make_span(models_), identity);
+    }
+
+    // Showing joints
+    if (show_joints_) {
+      const float kSphereRadius = .02f;
+      for (int i = 0; i < chain_length_; ++i) {
+        const ozz::math::Float4x4& transform = models_[joints_chain_[i]];
+        success &= _renderer->DrawAxes(transform * kAxesScale);
+        success &= _renderer->DrawSphereIm(kSphereRadius, transform,
+                                           ozz::sample::kWhite);
+      }
+    }
+
+    // Showing target, as a box or axes depending on show_forward_ option.
+    if (show_target_) {
+      const ozz::math::Float4x4 target = ozz::math::Float4x4::Translation(
+          ozz::math::simd_float4::Load3PtrU(&target_.x));
+      if (show_forward_) {
+        success &= _renderer->DrawAxes(target * kAxesScale);
+      } else {
+        success &= _renderer->DrawSphereIm(.02f, target, ozz::sample::kGreen);
+      }
+    }
+
+    if (show_eyes_offset_ || show_forward_) {
+      const int head = joints_chain_[0];
+      const ozz::math::Float4x4 offset =
+          models_[head] *
+          ozz::math::Float4x4::Translation(
+              ozz::math::simd_float4::Load3PtrU(&eyes_offset_.x));
+      if (show_eyes_offset_) {
+        success &= _renderer->DrawAxes(offset * kAxesScale);
+      }
+      if (show_forward_) {
+        ozz::math::Float3 begin;
+        ozz::math::Store3PtrU(offset.cols[3], &begin.x);
+        ozz::math::Float3 forward;
+        ozz::math::Store3PtrU(kHeadForward, &forward.x);
+        ozz::sample::Color color = {0xff, 0xff, 0xff, 0xff};
+        success &= _renderer->DrawSegment(ozz::math::Float3::zero(),
+                                          forward * 10.f, color, offset);
+      }
+    }
+    return success;
+  }
+
+  virtual bool OnInitialize() {
+    // Reading skeleton.
+    if (!ozz::sample::LoadSkeleton(OPTIONS_skeleton, &skeleton_)) {
+      return false;
+    }
+
+    // Look for each joint in the chain.
+    int found = 0;
+    for (int i = 0; i < skeleton_.num_joints() && found != kMaxChainLength;
+         ++i) {
+      const char* joint_name = skeleton_.joint_names()[i];
+      if (std::strcmp(joint_name, kJointNames[found]) == 0) {
+        joints_chain_[found] = i;
+
+        // Restart search
+        ++found;
+        i = 0;
+      }
+    }
+
+    // Exit if all joints weren't found.
+    if (found != kMaxChainLength) {
+      ozz::log::Err()
+          << "At least a joint wasn't found in the skeleton hierarchy."
+          << std::endl;
+      return false;
+    }
+
+    // Validates joints are order from child to parent of the same hierarchy.
+    if (!ValidateJointsOrder(skeleton_, joints_chain_)) {
+      ozz::log::Err() << "Joints aren't properly ordered, they must be from "
+                         "the same hierarchy (all ancestors of the first joint "
+                         "listed) and ordered from child to parent."
+                      << std::endl;
+      return false;
+    }
+
+    // Allocates runtime buffers.
+    const int num_soa_joints = skeleton_.num_soa_joints();
+    locals_.resize(num_soa_joints);
+    const int num_joints = skeleton_.num_joints();
+    models_.resize(num_joints);
+
+    // Allocates a cache that matches animation requirements.
+    cache_.Resize(num_joints);
+
+    // Reading animation.
+    if (!ozz::sample::LoadAnimation(OPTIONS_animation, &animation_)) {
+      return false;
+    }
+
+    // Reading character mesh.
+    if (!ozz::sample::LoadMeshes(OPTIONS_mesh, &meshes_)) {
+      return false;
+    }
+
+    // The number of joints of the mesh needs to match skeleton.
+    for (size_t m = 0; m < meshes_.size(); ++m) {
+      const ozz::sample::Mesh& mesh = meshes_[m];
+      if (num_joints < mesh.highest_joint_index()) {
+        ozz::log::Err() << "The provided mesh doesn't match skeleton "
+                           "(joint count mismatch)."
+                        << std::endl;
+        return false;
+      }
+    }
+    skinning_matrices_.resize(num_joints);
+
+    return true;
+  }
+
+  // Traverses the hierarchy from the first joint to the root, to check if
+  // joints are all ancestors (same branch), and ordered.
+  bool ValidateJointsOrder(const ozz::animation::Skeleton& _skeleton,
+                           ozz::span<const int> _joints) {
+    const size_t count = _joints.size();
+    if (count == 0) {
+      return true;
+    }
+
+    size_t i = 1;
+    for (int joint = _joints[0], parent = _skeleton.joint_parents()[joint];
+         i != count && joint != ozz::animation::Skeleton::kNoParent;
+         joint = parent, parent = _skeleton.joint_parents()[joint]) {
+      if (parent == _joints[i]) {
+        ++i;
+      }
+    }
+
+    return count == i;
+  }
+
+  virtual void OnDestroy() {}
+
+  virtual bool OnGui(ozz::sample::ImGui* _im_gui) {
+    char txt[64];
+
+    _im_gui->DoCheckBox("Enable ik", &enable_ik_);
+    sprintf(txt, "IK chain length: %d", chain_length_);
+    _im_gui->DoSlider(txt, 0, kMaxChainLength, &chain_length_);
+    sprintf(txt, "Joint weight %.2g", joint_weight_);
+    _im_gui->DoSlider(txt, 0.f, 1.f, &joint_weight_);
+    sprintf(txt, "Chain weight %.2g", chain_weight_);
+    _im_gui->DoSlider(txt, 0.f, 1.f, &chain_weight_);
+
+    // Exposes animation runtime playback controls.
+    {
+      static bool open = true;
+      ozz::sample::ImGui::OpenClose oc(_im_gui, "Animation control", &open);
+      if (open) {
+        controller_.OnGui(animation_, _im_gui);
+      }
+    }
+
+    {  // Target position
+      static bool opened = true;
+      ozz::sample::ImGui::OpenClose oc(_im_gui, "Target offset", &opened);
+      if (opened) {
+        const float kTargetRange = 3.f;
+
+        _im_gui->DoLabel("Animated extent");
+        sprintf(txt, "%.2g", target_extent_);
+        _im_gui->DoSlider(txt, 0.f, kTargetRange, &target_extent_);
+
+        sprintf(txt, "x %.2g", target_offset_.x);
+        _im_gui->DoSlider(txt, -kTargetRange, kTargetRange, &target_offset_.x);
+        sprintf(txt, "y %.2g", target_offset_.y);
+        _im_gui->DoSlider(txt, -kTargetRange, kTargetRange, &target_offset_.y);
+        sprintf(txt, "z %.2g", target_offset_.z);
+        _im_gui->DoSlider(txt, -kTargetRange, kTargetRange, &target_offset_.z);
+      }
+    }
+
+    {  // Offset position
+      static bool opened = true;
+      ozz::sample::ImGui::OpenClose oc(_im_gui, "Eyes offset", &opened);
+      if (opened) {
+        const float kOffsetRange = .5f;
+        sprintf(txt, "x %.2g", eyes_offset_.x);
+        _im_gui->DoSlider(txt, -kOffsetRange, kOffsetRange, &eyes_offset_.x);
+        sprintf(txt, "y %.2g", eyes_offset_.y);
+        _im_gui->DoSlider(txt, -kOffsetRange, kOffsetRange, &eyes_offset_.y);
+        sprintf(txt, "z %.2g", eyes_offset_.z);
+        _im_gui->DoSlider(txt, -kOffsetRange, kOffsetRange, &eyes_offset_.z);
+      }
+    }
+
+    // Options
+    {
+      _im_gui->DoCheckBox("Show skin", &show_skin_);
+      _im_gui->DoCheckBox("Show joints", &show_joints_);
+      _im_gui->DoCheckBox("Show target", &show_target_);
+      _im_gui->DoCheckBox("Show eyes offset", &show_eyes_offset_);
+      _im_gui->DoCheckBox("Show forward", &show_forward_);
+    }
+
+    return true;
+  }
+
+  virtual void GetSceneBounds(ozz::math::Box* _bound) const {
+    const ozz::math::Float3 radius(target_extent_ * .8f);
+    _bound->min = target_offset_ - radius;
+    _bound->max = target_offset_ + radius;
+  }
+
+ private:
+  // Playback animation controller. This is a utility class that helps with
+  // controlling animation playback time.
+  ozz::sample::PlaybackController controller_;
+
+  // Runtime skeleton.
+  ozz::animation::Skeleton skeleton_;
+
+  // Runtime animation.
+  ozz::animation::Animation animation_;
+
+  // Sampling cache.
+  ozz::animation::SamplingCache cache_;
+
+  // Buffer of local transforms as sampled from animation_.
+  ozz::vector<ozz::math::SoaTransform> locals_;
+
+  // Buffer of model-space matrices.
+  ozz::vector<ozz::math::Float4x4> models_;
+
+  // Buffer of skinning matrices, result of the joint multiplication of the
+  // inverse bind pose with the model-space matrix.
+  ozz::vector<ozz::math::Float4x4> skinning_matrices_;
+
+  // The mesh used by the sample.
+  ozz::vector<ozz::sample::Mesh> meshes_;
+
+  // Indices of the joints that are IKed for look-at purpose.
+  // Joints must be from the same hierarchy (all ancestors of the first joint
+  // listed) and ordered from child to parent.
+  int joints_chain_[kMaxChainLength];
+
+  // Sample settings
+
+  // Target position management.
+  ozz::math::Float3 target_offset_;
+  float target_extent_;
+  ozz::math::Float3 target_;
+
+  // Offset of the look at position in (head) joint local-space.
+  ozz::math::Float3 eyes_offset_;
+
+  // IK settings
+
+  // Enable IK look at.
+  bool enable_ik_;
+
+  // Set length of the chain that is IKed, between 0 and kMaxChainLength.
+  int chain_length_;
+
+  // Weight given to every joint of the chain. If any joint has a weight of 1,
+  // no other following joint will contribute (as the target will be reached).
+  float joint_weight_;
+
+  // Overall weight given to the IK on the full chain. This allows blending in
+  // and out of IK.
+  float chain_weight_;
+
+  // Options
+  bool show_skin_;
+  bool show_joints_;
+  bool show_target_;
+  bool show_eyes_offset_;
+  bool show_forward_;
+};
+
+int main(int _argc, const char** _argv) {
+  const char* title = "Ozz-animation sample: Look at";
+  return LookAtSampleApplication().Run(_argc, _argv, "1.0", title);
+}