Added graph design ramblings.

.gitignore

@@ -1,5 +1,7 @@
 .*.swp
 
+*.fbx
+*blend1
 *CMakeFiles/**
 /.idea
 /scratch*

3rdparty/ozz-animation/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 3.3)
+cmake_minimum_required (VERSION 3.20)
 
 # Defines the project's name
 project(ozz)

3rdparty/ozz-animation/include/ozz/base/containers/std_allocator.h

@@ -49,7 +49,7 @@ class StdAllocator {
   StdAllocator(const StdAllocator&) noexcept {}
 
   template <class _Other>
-  StdAllocator<value_type>(const StdAllocator<_Other>&) noexcept {}
+  StdAllocator(const StdAllocator<_Other>&) noexcept {}
 
   template <class _Other>
   struct rebind {

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.13)
 
-cmake_policy(SET CMP0077 NEW)
+set(CMAKE_POLICY_DEFAULT_CMP0077 NEW)
 
 project(AnimTestbed
         VERSION 0.0.1
@@ -28,31 +28,66 @@ set(ozz_build_simd_ref OFF CACHE BOOL "")
 set(ozz_build_msvc_rt_dll OFF CACHE BOOL "")
 add_subdirectory(3rdparty/ozz-animation)
 
-# Simulator Executable
-add_executable(AnimTestbed)
-target_include_directories(
-        AnimTestbed
+set (ThirdPartyIncludeDeps
         PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
         PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/glfw/deps>
+        PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/glfw/deps>
         PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/Handmade-Math>
         PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/imgui>
+        PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/ozz-animation/include>
         PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/sokol>
         PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/3rdparty/vectorial/include>
-)
-target_link_libraries(AnimTestbed glfw ozz_base ozz_geometry ozz_animation ${OPENGL_LIBRARIES})
+        )
 
-target_sources(AnimTestbed PRIVATE
-        src/main.cc
+# Shared code by main executable and tests
+add_library(AnimTestbedCode OBJECT
         src/Camera.c
         src/SkinnedMesh.cc
         src/SkinnedMesh.h
+        src/SyncTrack.cc
+        src/SyncTrack.h
+        src/AnimNode.cc
+        src/AnimNodes/AnimSamplerNode.cc
+        src/AnimNodes/SpeedScaleNode.cc
+        src/AnimNodes/BlendNode.cc
+        src/AnimNodes/LockTranslationNode.cc
         src/AnimationController.cc
-        src/BlendNode.cc
-        3rdparty/glfw/deps/glad_gl.c
         3rdparty/imgui/imgui.cpp
         3rdparty/imgui/imgui_draw.cpp
         3rdparty/imgui/imgui_widgets.cpp
+        )
+
+target_include_directories(
+        AnimTestbedCode
+        ${ThirdPartyIncludeDeps}
+)
+
+# AnimTestbed Executable
+add_executable(AnimTestbed)
+target_include_directories(
+        AnimTestbed
+        ${ThirdPartyIncludeDeps}
+)
+
+target_sources(AnimTestbed PRIVATE
+        src/main.cc
+        src/SkinnedMeshRenderer.cc
+        3rdparty/glfw/deps/glad_gl.c
         3rdparty/imgui/imgui_demo.cpp
         3rdparty/imgui/backends/imgui_impl_glfw.cpp
         3rdparty/imgui/backends/imgui_impl_opengl3.cpp
         )
+
+target_link_libraries(AnimTestbed AnimTestbedCode glfw ozz_base ozz_geometry ozz_animation ${OPENGL_LIBRARIES})
+
+# Tests
+add_executable(runtests)
+
+target_sources(runtests PRIVATE tests/main.cc tests/SyncTrackTests.cc)
+target_include_directories(
+        runtests
+        PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
+        ${ThirdPartyIncludeDeps}
+)
+
+target_link_libraries(runtests AnimTestbedCode glfw ozz_base ozz_geometry ozz_animation)

doc/design.md

@@ -0,0 +1,35 @@
+## Graph
+
+### 1. Support of math nodes (or non-AnimNodes in general)
+
+* Enables animators to add custom math for blend inputs or to adjust other inputs (e.g. LookAt or IK
+  targets).
+
+**Open Issues**
+
+1. When to do the evaluation? Two types of subgraphs:
+   a) Instant inputs (needed for blend node inputs) that have to be evaluated before
+   UpdateConnections
+   b) Processing nodes, e.g. for extracted bones.
+
+### 2. Support of multiple output sockets
+
+* E.g. extract Bone transform
+
+* Increases Node complexity:
+    * AnimOutput
+    * AnimOutput + Data
+    * Data
+
+(Data = bool, float, vec3, quat, ...)
+
+**Open Issues**
+
+1. Unclear when this is actually needed. Using more specific nodes that perform the desired logic
+   may be better (
+   c.f. https://dev.epicgames.com/documentation/en-us/unreal-engine/animation-blueprint-bone-driven-controller-in-unreal-engine).
+   Likely this is not crucial so should be avoided for now.
+
+### 3. Multi-skeleton evaluation
+
+Use case: riding on a horse, interaction between two characters.

src/AnimNode.cc

@@ -0,0 +1,5 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#include "AnimNode.h"

src/AnimNode.h

@@ -0,0 +1,53 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#ifndef ANIMTESTBED_ANIMNODE_H
+#define ANIMTESTBED_ANIMNODE_H
+
+#include <string>
+
+#include "AnimationController.h"
+#include "SkinnedMesh.h"
+
+enum class AnimNodeType { Blend, SpeedScale, AnimSampler };
+
+struct AnimNode {
+  AnimNode(AnimationController* animation_controller)
+      : m_animation_controller(animation_controller),
+        m_current_time(0.f),
+        m_is_time_synced(false) {}
+  virtual ~AnimNode(){};
+
+  AnimNodeType m_anim_node_type;
+  std::string m_name;
+  AnimationController* m_animation_controller;
+
+  // When synced then current time is relative to the node's anim duration.:w
+  bool m_is_time_synced;
+  float m_current_time;
+  SyncTrack m_sync_track;
+
+  virtual void Reset() { m_current_time = 0.f; }
+
+  // Mark current node according to is_synced and propagate flag to animation inputs.
+  virtual void UpdateIsSynced(bool is_synced) = 0;
+
+  // Evaluate the animation duration of this node. All input nodes must have already evaluated
+  // their anim durations.
+  virtual void UpdateSyncTrack() = 0;
+
+  // Evaluate current time and propagate time step to inputs.
+  virtual void UpdateTime(float dt) = 0;
+
+  // Evaluate the current node and write output to local_matrices.
+  virtual void Evaluate(
+      ozz::vector<ozz::math::SoaTransform>* local_matrices) = 0;
+
+  // Returns a list of animation nodes that provide input for this node.
+  virtual void GetInputNodes(std::vector<AnimNode*>& input_nodes) const = 0 ;
+
+  virtual void DrawDebugUi(){};
+};
+
+#endif  //ANIMTESTBED_ANIMNODE_H

src/AnimNodes/AnimSamplerNode.cc

@@ -0,0 +1,58 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#include "AnimSamplerNode.h"
+
+#include <imgui.h>
+
+#include "../SkinnedMesh.h"
+
+void AnimSamplerNode::SetAnimation(ozz::animation::Animation* animation, const SyncTrack& sync_track) {
+  m_animation = animation;
+
+  const SkinnedMesh* skinned_mesh = m_animation_controller->m_skinned_mesh;
+  const int num_soa_joints = skinned_mesh->m_skeleton.num_soa_joints();
+  const int num_joints = skinned_mesh->m_skeleton.num_joints();
+  m_local_matrices.resize(num_soa_joints);
+  m_sampling_cache.Resize(num_joints);
+
+  m_sync_track = sync_track;
+}
+
+void AnimSamplerNode::Evaluate(
+    ozz::vector<ozz::math::SoaTransform>* local_matrices) {
+  ozz::animation::SamplingJob sampling_job;
+  sampling_job.animation = m_animation;
+  sampling_job.cache = &m_sampling_cache;
+  sampling_job.ratio = m_anim_ratio;
+  sampling_job.output = make_span(*local_matrices);
+  if (!sampling_job.Run()) {
+    ozz::log::Err() << "Error sampling animation." << std::endl;
+  }
+}
+
+void AnimSamplerNode::DrawDebugUi() {
+  const SkinnedMesh* skinned_mesh = m_animation_controller->m_skinned_mesh;
+  int anim_count = skinned_mesh->m_animation_names.size();
+  const char* items[255] = {0};
+  int item_current = 0;
+  for (int i = 0; i < anim_count; i++) {
+    items[i] = skinned_mesh->m_animation_names[i].c_str();
+    if (skinned_mesh->m_animations[i] == m_animation) {
+      item_current = i;
+    }
+  }
+
+  if (ImGui::Combo("Animation", &item_current, items, anim_count)) {
+    m_animation = skinned_mesh->m_animations[item_current];
+    m_sync_track = skinned_mesh->m_animation_sync_track[item_current];
+  }
+
+  ImGui::Checkbox("Override", &m_override_ratio);
+  ImGui::SameLine();
+  ImGui::SliderFloat("Ratio", &m_anim_ratio, 0.f, 1.f);
+
+  ImGui::Text("SyncTrack");
+  m_sync_track.DrawDebugUi();
+}

src/AnimNodes/AnimSamplerNode.h

@@ -0,0 +1,60 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#ifndef ANIMTESTBED_ANIMSAMPLERNODE_H
+#define ANIMTESTBED_ANIMSAMPLERNODE_H
+
+#include "../AnimNode.h"
+
+struct AnimSamplerNode : public AnimNode {
+  AnimSamplerNode(AnimationController* animation_controller)
+      : AnimNode(animation_controller),
+        m_override_ratio(false),
+        m_anim_ratio(0.f) {
+    assert(m_current_time < 100.0f);
+    m_anim_node_type = AnimNodeType::AnimSampler;
+  };
+  virtual ~AnimSamplerNode() {}
+
+  ozz::animation::Animation* m_animation;
+
+  bool m_override_ratio;
+  float m_anim_ratio;
+
+  ozz::vector<ozz::math::SoaTransform> m_local_matrices;
+  ozz::animation::SamplingCache m_sampling_cache;
+
+  void SetAnimation(ozz::animation::Animation* animation, const SyncTrack& sync_track);
+
+  virtual void UpdateIsSynced(bool is_synced) override {
+    m_is_time_synced = is_synced;
+  }
+
+  virtual void UpdateSyncTrack() override {
+  }
+
+  virtual void UpdateTime(float dt) override {
+    m_current_time += dt;
+    if (!m_override_ratio) {
+      if (m_is_time_synced) {
+        m_anim_ratio = m_sync_track.CalcRatioFromSyncTime(m_current_time);
+      } else {
+        m_anim_ratio = fmodf((float)m_current_time / m_animation->duration(), 1.0f);
+      }
+    }
+
+    if (m_anim_ratio < 0.f) {
+      m_anim_ratio += 1.0f;
+    }
+  }
+
+  virtual void Evaluate(
+      ozz::vector<ozz::math::SoaTransform>* local_matrices) override;
+
+  virtual void GetInputNodes(std::vector<AnimNode*>& input_nodes) const override{};
+
+  virtual void DrawDebugUi();
+};
+
+#endif  //ANIMTESTBED_ANIMSAMPLERNODE_H

src/AnimNodes/BlendNode.cc

@@ -0,0 +1,59 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#include "BlendNode.h"
+
+#include <imgui.h>
+#include <ozz/animation/runtime/blending_job.h>
+
+#include "../SkinnedMesh.h"
+
+BlendNode::BlendNode(AnimationController* animation_controller)
+    : AnimNode(animation_controller),
+      m_input_A(nullptr),
+      m_input_B(nullptr),
+      m_weight(0.f),
+      m_sync_inputs(false) {
+  m_anim_node_type = AnimNodeType::Blend;
+  const SkinnedMesh* skinned_mesh = m_animation_controller->m_skinned_mesh;
+  const int num_soa_joints = skinned_mesh->m_skeleton.num_soa_joints();
+  const int num_joints = skinned_mesh->m_skeleton.num_joints();
+  m_local_matrices_A.resize(num_soa_joints);
+  m_local_matrices_B.resize(num_soa_joints);
+}
+
+void BlendNode::Evaluate(ozz::vector<ozz::math::SoaTransform>* local_matrices) {
+  const SkinnedMesh* skinned_mesh = m_animation_controller->m_skinned_mesh;
+
+  m_input_A->Evaluate(&m_local_matrices_A);
+  m_input_B->Evaluate(&m_local_matrices_B);
+
+  // perform blend
+  ozz::animation::BlendingJob::Layer layers[2];
+  layers[0].transform = make_span(m_local_matrices_A);
+  layers[0].weight = (1.0f - m_weight);
+
+  layers[1].transform = make_span(m_local_matrices_B);
+  layers[1].weight = (m_weight);
+
+  ozz::animation::BlendingJob blend_job;
+  blend_job.threshold = ozz::animation::BlendingJob().threshold;
+  blend_job.layers = layers;
+  blend_job.bind_pose = skinned_mesh->m_skeleton.joint_bind_poses();
+  blend_job.output = make_span(*local_matrices);
+
+  if (!blend_job.Run()) {
+    ozz::log::Err() << "Error blending animations." << std::endl;
+  }
+}
+
+void BlendNode::DrawDebugUi() {
+  if (ImGui::SliderFloat("Weight", &m_weight, 0.f, 1.f)) {
+    m_sync_track = SyncTrack::Blend(m_weight, m_input_A->m_sync_track, m_input_B->m_sync_track);
+  }
+  ImGui::Checkbox("Sync Inputs", &m_sync_inputs);
+
+  ImGui::Text("SyncTrack");
+  m_sync_track.DrawDebugUi();
+}

src/AnimNodes/BlendNode.h

@@ -0,0 +1,71 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#ifndef ANIMTESTBED_BLENDNODE_H
+#define ANIMTESTBED_BLENDNODE_H
+
+#include "../AnimNode.h"
+
+struct BlendNode : public AnimNode {
+  BlendNode(AnimationController* animation_controller);
+
+  virtual ~BlendNode() {}
+
+  AnimNode* m_input_A;
+  AnimNode* m_input_B;
+  float m_weight;
+  bool m_sync_inputs;
+
+  ozz::vector<ozz::math::SoaTransform> m_local_matrices_A;
+  ozz::vector<ozz::math::SoaTransform> m_local_matrices_B;
+
+  virtual void Reset() {
+    m_current_time = 0.f;
+  }
+
+  virtual void UpdateIsSynced(bool is_synced) override {
+    m_is_time_synced = is_synced;
+
+    if (m_sync_inputs) {
+      m_is_time_synced = true;
+    }
+
+    m_input_B->UpdateIsSynced(m_is_time_synced);
+    m_input_A->UpdateIsSynced(m_is_time_synced);
+  }
+
+  virtual void UpdateSyncTrack() override {
+    if (m_is_time_synced) {
+      m_sync_track = SyncTrack::Blend(m_weight, m_input_A->m_sync_track, m_input_B->m_sync_track);
+    } else {
+      assert (false);
+    }
+  }
+
+  virtual void UpdateTime(float dt) {
+    if (m_is_time_synced) {
+      m_current_time = fmodf(m_current_time + dt, m_sync_track.m_duration);
+      float current_sync_time = m_sync_track.CalcSyncFromAbsTime(m_current_time);
+
+      m_input_A->UpdateTime(current_sync_time - m_input_A->m_current_time);
+      m_input_B->UpdateTime(current_sync_time - m_input_B->m_current_time);
+    } else {
+      m_current_time += dt;
+      m_input_A->UpdateTime(dt);
+      m_input_B->UpdateTime(dt);
+    }
+  }
+
+  virtual void Evaluate(
+      ozz::vector<ozz::math::SoaTransform>* local_matrices) override;
+
+  virtual void GetInputNodes(std::vector<AnimNode*>& input_nodes) const override {
+    input_nodes.push_back(m_input_A);
+    input_nodes.push_back(m_input_B);
+  };
+
+  virtual void DrawDebugUi();
+};
+
+#endif  //ANIMTESTBED_BLENDNODE_H

src/AnimNodes/LockTranslationNode.cc

@@ -0,0 +1,59 @@
+//
+// Created by martin on 16.11.21.
+//
+
+#include "LockTranslationNode.h"
+
+#include <imgui.h>
+#include "ozz/base/maths/soa_transform.h"
+
+void LockTranslationNode::Evaluate(
+    ozz::vector<ozz::math::SoaTransform>* local_matrices) {
+  m_input->Evaluate(local_matrices);
+  ozz::math::SoaFloat3 translation = (*local_matrices)[m_locked_bone_index].translation;
+  float x[4];
+  float y[4];
+  float z[4];
+  _mm_store_ps(x, translation.x);
+  _mm_store_ps(y, translation.y);
+  _mm_store_ps(z, translation.z);
+
+  if (m_lock_x) {
+    x[0] = 0.f;
+  }
+
+  if (m_lock_y) {
+    y[0] = 0.f;
+  }
+
+  if (m_lock_z) {
+    z[0] = 0.f;
+  }
+
+  translation.x = _mm_load_ps(x);
+  translation.y = _mm_load_ps(y);
+  translation.z = _mm_load_ps(z);
+
+  //translation = ozz::math::SoaFloat3::zero();
+//  ozz::math::SetX(translation, 0.f);
+//  ozz::math::SetZ(translation, 0.f);
+   (*local_matrices)[m_locked_bone_index].translation = translation;
+}
+
+void LockTranslationNode::DrawDebugUi() {
+  const ozz::animation::Skeleton& skeleton = m_animation_controller->m_skinned_mesh->m_skeleton;
+  ozz::span<const char* const> joint_names = skeleton.joint_names();
+
+  const char* items[255] = {0};
+  int item_current = 0;
+  for (int i = 0; i < joint_names.size(); i++) {
+    items[i] = joint_names[i];
+  }
+
+  ImGui::Combo("Bone", &m_locked_bone_index, items, joint_names.size());
+  ImGui::Checkbox("Lock X", &m_lock_x);
+  ImGui::Checkbox("Lock Y", &m_lock_y);
+  ImGui::Checkbox("Lock Z", &m_lock_z);
+
+
+}

src/AnimNodes/LockTranslationNode.h

@@ -0,0 +1,52 @@
+//
+// Created by martin on 16.11.21.
+//
+
+#ifndef ANIMTESTBED_LOCKBONES_H
+#define ANIMTESTBED_LOCKBONES_H
+
+#include "../AnimNode.h"
+
+struct LockTranslationNode : public AnimNode {
+  LockTranslationNode(AnimationController* animation_controller)
+      : AnimNode(animation_controller),
+        m_input(nullptr),
+        m_locked_bone_index(0),
+        m_lock_x(false),
+        m_lock_y(false),
+        m_lock_z(false) {}
+
+  virtual ~LockTranslationNode() {}
+
+  AnimNode* m_input;
+  int m_locked_bone_index;
+  bool m_lock_x;
+  bool m_lock_y;
+  bool m_lock_z;
+
+  virtual void Reset() { m_current_time = 0.f; }
+
+  virtual void UpdateIsSynced(bool is_synced) override {
+    m_is_time_synced = is_synced;
+
+    m_input->UpdateIsSynced(m_is_time_synced);
+  }
+
+  virtual void UpdateSyncTrack() override {
+    m_sync_track = m_input->m_sync_track;
+  }
+
+  virtual void UpdateTime(float dt) { m_input->UpdateTime(dt); }
+
+  virtual void Evaluate(
+      ozz::vector<ozz::math::SoaTransform>* local_matrices) override;
+
+  virtual void GetInputNodes(
+      std::vector<AnimNode*>& input_nodes) const override {
+    input_nodes.push_back(m_input);
+  };
+
+  virtual void DrawDebugUi() override;
+};
+
+#endif  //ANIMTESTBED_LOCKBONES_H

src/AnimNodes/SpeedScaleNode.cc

@@ -0,0 +1,24 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#include "SpeedScaleNode.h"
+
+#include <imgui.h>
+
+void SpeedScaleNode::DrawDebugUi() {
+  bool is_negative = m_time_scale < 0.f;
+  if (ImGui::Checkbox("Reverse Time", &is_negative)) {
+    m_time_scale = m_time_scale * -1.f;
+  }
+
+  // ensure m_time_scale is positive
+  m_time_scale = m_time_scale * (is_negative ? -1.f : 1.f);
+  if (ImGui::SliderFloat("Time Scale", &m_time_scale, 0.01f, 2.f)) {
+    if (fabs(m_time_scale - 1.0) < 0.2) {
+      m_time_scale = 1.0;
+    }
+  }
+  // and back to the original negative or positive sign
+  m_time_scale = m_time_scale * (is_negative ? -1.f : 1.f);
+}

src/AnimNodes/SpeedScaleNode.h

@@ -0,0 +1,54 @@
+//
+// Created by martin on 12.11.21.
+//
+
+#ifndef ANIMTESTBED_SPEEDSCALENODE_H
+#define ANIMTESTBED_SPEEDSCALENODE_H
+
+#include "../AnimNode.h"
+
+struct SpeedScaleNode : public AnimNode {
+  SpeedScaleNode(AnimationController* animation_controller)
+      : AnimNode(animation_controller), m_time_scale(1.f) {
+    m_anim_node_type = AnimNodeType::SpeedScale;
+  }
+
+  float m_time_scale;
+  AnimNode* m_input_node;
+
+  virtual void Reset() { m_current_time = 0.f; }
+
+  virtual void UpdateIsSynced(bool is_synced) override {
+    m_is_time_synced = is_synced;
+    m_input_node->UpdateIsSynced(is_synced);
+  }
+
+  virtual void UpdateSyncTrack() override {
+    assert(fabs(m_time_scale) >= 0.01f);
+    m_sync_track = m_input_node->m_sync_track;
+    m_sync_track.m_duration =fabsf(m_input_node->m_sync_track.m_duration / m_time_scale);
+  }
+
+  virtual void UpdateTime(float dt) {
+    if (!m_is_time_synced) {
+      m_current_time += dt * m_time_scale;
+      m_input_node->UpdateTime(dt * m_time_scale);
+    } else {
+      m_current_time += dt;
+      m_input_node->UpdateTime(dt);
+    }
+  }
+
+  virtual void Evaluate(
+      ozz::vector<ozz::math::SoaTransform>* local_matrices) override {
+    m_input_node->Evaluate(local_matrices);
+  };
+
+  virtual void GetInputNodes(std::vector<AnimNode*>& input_nodes) const override {
+      input_nodes.push_back(m_input_node);
+  };
+
+  virtual void DrawDebugUi() override;
+};
+
+#endif  //ANIMTESTBED_SPEEDSCALENODE_H

src/AnimationController.cc

@@ -5,134 +5,209 @@
 #include "AnimationController.h"
 
 #include <imgui.h>
-#include <ozz/animation/runtime/blending_job.h>
 #include <ozz/animation/runtime/local_to_model_job.h>
 #include <ozz/animation/runtime/sampling_job.h>
 
+#include <queue>
+
+#include "AnimNodes/AnimSamplerNode.h"
+#include "AnimNodes/BlendNode.h"
+#include "AnimNodes/LockTranslationNode.h"
+#include "AnimNodes/SpeedScaleNode.h"
 #include "SkinnedMesh.h"
 
 AnimationController::AnimationController(SkinnedMesh* skinned_mesh)
-    : m_current_time(0.f),
-      m_skinned_mesh(skinned_mesh),
-      m_blend_anim_A(nullptr),
-      m_blend_anim_B(nullptr),
-      m_blend_weight(0.f),
-      m_time_scale_A(1.f),
-      m_time_scale_B(1.f),
-      m_override_ratio_A(false),
-      m_override_ratio_B(false) {
+    : m_current_time(0.f), m_paused(true), m_skinned_mesh(skinned_mesh) {
   const int num_soa_joints = skinned_mesh->m_skeleton.num_soa_joints();
   const int num_joints = skinned_mesh->m_skeleton.num_joints();
   skinned_mesh->m_local_matrices.resize(num_soa_joints);
   skinned_mesh->m_model_matrices.resize(num_joints);
 
-  m_sampling_cache_A.Resize(num_joints);
-  m_sampling_cache_B.Resize(num_joints);
-
-  m_local_matrices_A.resize(num_soa_joints);
-  m_local_matrices_B.resize(num_soa_joints);
-  m_local_matrices_blended.resize(num_soa_joints);
-
-  assert(skinned_mesh->m_animations.size() > 1);
-  SetBlendAnims(skinned_mesh->m_animations[1], skinned_mesh->m_animations[0]);
   ResetAnims();
+
+  AnimSamplerNode* sampler_node0 = new AnimSamplerNode(this);
+  sampler_node0->m_name = "AnimSampler0";
+  sampler_node0->SetAnimation(skinned_mesh->m_animations[1], skinned_mesh->m_animation_sync_track[1]);
+  m_anim_nodes.push_back(sampler_node0);
+
+  AnimSamplerNode* sampler_node1 = new AnimSamplerNode(this);
+  sampler_node1->m_name = "AnimSampler1";
+  sampler_node1->SetAnimation(skinned_mesh->m_animations[2], skinned_mesh->m_animation_sync_track[2]);
+  m_anim_nodes.push_back(sampler_node1);
+
+  SpeedScaleNode* speed_node = new SpeedScaleNode(this);
+  speed_node->m_name = "SpeedNode0";
+  speed_node->m_input_node = sampler_node0;
+  m_anim_nodes.push_back(speed_node);
+
+  BlendNode* blend_node = new BlendNode(this);
+  blend_node->m_name = "Blend0";
+  blend_node->m_input_A = speed_node;
+  blend_node->m_input_B = sampler_node1;
+  blend_node->m_sync_inputs = true;
+  m_anim_nodes.push_back(blend_node);
+
+  SpeedScaleNode* speed_node1 = new SpeedScaleNode(this);
+  speed_node1->m_name = "SpeedNode1";
+  speed_node1->m_input_node = blend_node;
+  m_anim_nodes.push_back(speed_node1);
+
+  LockTranslationNode* lock_node = new LockTranslationNode(this);
+  lock_node->m_name = "LockNode0";
+  lock_node->m_locked_bone_index = 0;
+  lock_node->m_input = speed_node1;
+  m_anim_nodes.push_back(lock_node);
+
+  m_output_node = m_anim_nodes.back();
+
+  UpdateOrderedNodes();
+
+  m_output_node->Reset();
 }
 
-void AnimationController::Update(float dt) {
-  m_current_time += dt;
-  if (!m_override_ratio_A) {
-    m_anim_time_A += dt * m_time_scale_A;
-    const float duration_A = m_blend_anim_A->duration();
-    m_anim_ratio_A = fmodf((float)m_anim_time_A / duration_A, 1.0f);
+AnimationController::~AnimationController() {
+  while (m_anim_nodes.size() > 0) {
+    delete m_anim_nodes[m_anim_nodes.size() - 1];
+    m_anim_nodes.pop_back();
   }
 
-  if (!m_override_ratio_B) {
-    m_anim_time_B += dt * m_time_scale_B;
-    const float duration_B = m_blend_anim_B->duration();
-    m_anim_ratio_B = fmodf((float)m_anim_time_B / duration_B, 1.0f);
+  m_output_node = nullptr;
+}
+
+void AnimationController::ResetAnims() {
+  for (int i = 0; i < m_ordered_nodes.size(); i++) {
+    m_ordered_nodes[i]->Reset();
   }
 }
 
+void AnimationController::UpdateOrderedNodes() {
+  std::vector<AnimNode*> node_stack;
+  node_stack.push_back(m_output_node);
+
+  m_ordered_nodes.clear();
+
+  while (node_stack.size() > 0) {
+    AnimNode* node = node_stack.back();
+    m_ordered_nodes.push_back(node);
+    node_stack.pop_back();
+
+    std::vector<AnimNode*> node_inputs;
+    node->GetInputNodes(node_inputs);
+    for (int i = node_inputs.size() - 1; i >= 0; i--) {
+      node_stack.push_back(node_inputs[i]);
+    }
+  }
+}
+
+void AnimationController::UpdateTime(float dt) {
+  if (m_paused || m_output_node == nullptr) {
+    return;
+  }
+
+  // Mark all nodes that evaluate time using sync tracks.
+  m_output_node->UpdateIsSynced(false);
+
+  // For all synced nodes calculate their current sync track durations
+  for (int i = m_ordered_nodes.size() - 1; i >= 0; i--) {
+    AnimNode* node = m_ordered_nodes[i];
+    if (node->m_is_time_synced) {
+      node->UpdateSyncTrack();
+    }
+  }
+
+  // Update the time of all nodes.
+  m_output_node->UpdateTime(dt);
+}
+
 void AnimationController::Evaluate() {
-  // sample animation A
-  ozz::animation::SamplingJob sampling_job;
-  sampling_job.animation = m_blend_anim_A;
-  sampling_job.cache = &m_sampling_cache_A;
-  sampling_job.ratio = m_anim_ratio_A;
-  sampling_job.output = make_span(m_local_matrices_A);
-  if (!sampling_job.Run()) {
-    ozz::log::Err() << "Error sampling animation." << std::endl;
+  if (m_output_node == nullptr) {
+    return;
   }
 
-  // sample animation B
-  sampling_job.animation = m_blend_anim_B;
-  sampling_job.cache = &m_sampling_cache_B;
-  sampling_job.ratio = m_anim_ratio_B;
-  sampling_job.output = make_span(m_local_matrices_B);
-  if (!sampling_job.Run()) {
-    ozz::log::Err() << "Error sampling animation." << std::endl;
-  }
-
-  // perform blend
-  ozz::animation::BlendingJob::Layer layers[2];
-  layers[0].transform = make_span(m_local_matrices_A);
-  layers[0].weight = (1.0f - m_blend_weight);
-
-  layers[1].transform = make_span(m_local_matrices_B);
-  layers[1].weight = (m_blend_weight);
-
-  ozz::animation::BlendingJob blend_job;
-  blend_job.threshold = ozz::animation::BlendingJob().threshold;
-  blend_job.layers = layers;
-  blend_job.bind_pose = m_skinned_mesh->m_skeleton.joint_bind_poses();
-  blend_job.output = make_span(m_local_matrices_blended);
-
-  if (!blend_job.Run()) {
-    ozz::log::Err() << "Error blending animations." << std::endl;
-  }
-
-  // convert joint matrices from local to model space
-  ozz::animation::LocalToModelJob ltm_job;
-  ltm_job.skeleton = &m_skinned_mesh->m_skeleton;
-  ltm_job.input = make_span(m_local_matrices_blended);
-  ltm_job.output = make_span(m_skinned_mesh->m_model_matrices);
-  ltm_job.Run();
+  m_output_node->Evaluate(&m_skinned_mesh->m_local_matrices);
 };
 
 void AnimationController::DrawDebugUi() {
+  ImGui::SetNextWindowSize(ImVec2(500, 300), ImGuiCond_FirstUseEver);
   ImGui::Begin("AnimationController");
 
-  int anim_count = m_skinned_mesh->m_animation_names.size();
-  const char* items[255] = {0};
-  int item_current_A = 0;
-  int item_current_B = 0;
-  for (int i = 0; i < anim_count; i++) {
-    items[i] = m_skinned_mesh->m_animation_names[i].c_str();
-    if (m_skinned_mesh->m_animations[i] == m_blend_anim_A) {
-      item_current_A = i;
+  if (ImGui::Button("Reset")) {
+    ResetAnims();
   }
-    if (m_skinned_mesh->m_animations[i] == m_blend_anim_B) {
-      item_current_B = i;
+  ImGui::SameLine();
+  if (m_paused) {
+    if (ImGui::Button("Play")) {
+      m_paused = false;
     }
+  } else {
+    if (ImGui::Button("Pause")) {
+      m_paused = true;
+    }
+  }
+  ImGui::SameLine();
+  if (ImGui::Button("Step")) {
+    bool was_paused = m_paused;
+    m_paused = false;
+    UpdateTime(0.1);
+    Evaluate();
+    m_paused = was_paused;
   }
 
-  bool anim_changed = false;
-  anim_changed =
-      ImGui::Combo("Animation A", &item_current_A, items, anim_count);
-  ImGui::SliderFloat("Time Scale", &m_time_scale_A, 0.01f, 5.f);
-  ImGui::Checkbox("Override", &m_override_ratio_A);
-  ImGui::SameLine();
-  ImGui::SliderFloat("Ratio", &m_anim_ratio_A, 0.f, 1.f);
-  anim_changed = ImGui::Combo("Animation B", &item_current_B, items, anim_count)
-                 || anim_changed;
-  ImGui::SliderFloat("Time Scale##", &m_time_scale_B, 0.01f, 5.f);
-  ImGui::Checkbox("Override##", &m_override_ratio_B);
-  ImGui::SameLine();
-  ImGui::SliderFloat("Ratio##", &m_anim_ratio_B, 0.f, 1.f);
+  ImVec2 node_size(200, 100);
+  for (int i = 0; i < m_ordered_nodes.size(); i++) {
+    AnimNode* node = m_ordered_nodes[i];
+
+    ImGui::SetNextWindowSize(node_size, ImGuiCond_FirstUseEver);
+    ImGui::SetNextWindowPos(
+        ImVec2((m_ordered_nodes.size() - 1 - i) * node_size.x - i * 10, 300),
+        ImGuiCond_FirstUseEver);
+    ImGui::Begin(node->m_name.c_str());
+    node->DrawDebugUi();
+    ImGui::End();
+  }
+
+  ImGui::Text ("Node States");
+
+  ImGui::Columns(4, "Node States");  // 4-ways, with border
+  ImGui::Separator();
+  ImGui::Text("Name");
+  ImGui::NextColumn();
+  ImGui::Text("Synced");
+  ImGui::NextColumn();
+  ImGui::Text("Duration");
+  ImGui::NextColumn();
+  ImGui::Text("Time");
+  ImGui::NextColumn();
+
+  ImGui::Separator();
+  static int selected = -1;
+
+  for (int i = 0; i < m_ordered_nodes.size(); i++) {
+    AnimNode* node = m_ordered_nodes[i];
+    if (ImGui::Selectable(
+            node->m_name.c_str(),
+            selected == i,
+            ImGuiSelectableFlags_SpanAllColumns))
+      selected = i;
+    bool hovered = ImGui::IsItemHovered();
+    ImGui::NextColumn();
+
+    ImGui::Text(node->m_is_time_synced ? "X" : "-");
+    ImGui::NextColumn();
+
+    ImGui::PushID((void*)&node->m_sync_track.m_duration);
+    ImGui::Text("%2.3f", node->m_sync_track.m_duration);
+    ImGui::NextColumn();
+    ImGui::PopID();
+
+    ImGui::PushID((void*)&node->m_current_time);
+    ImGui::Text("%2.3f", node->m_current_time);
+    ImGui::NextColumn();
+    ImGui::PopID();
+  }
+
+  ImGui::Columns(1);
+  ImGui::Separator();
 
-  SetBlendAnims(
-      m_skinned_mesh->m_animations[item_current_A],
-      m_skinned_mesh->m_animations[item_current_B]);
-  ImGui::SliderFloat("Weight", &m_blend_weight, 0.f, 1.f);
   ImGui::End();
 }

src/AnimationController.h

@@ -5,56 +5,41 @@
 #ifndef ANIMTESTBED_ANIMATIONCONTROLLER_H
 #define ANIMTESTBED_ANIMATIONCONTROLLER_H
 
+#include <ozz/animation/runtime/animation.h>
 #include <ozz/animation/runtime/sampling_job.h>
-
-#include "ozz/animation/runtime/animation.h"
-#include "ozz/base/containers/vector.h"
-#include "ozz/base/maths/soa_transform.h"
-#include "ozz/base/maths/vec_float.h"
+#include <ozz/base/containers/vector.h>
+#include <ozz/base/maths/soa_transform.h>
+#include <ozz/base/maths/vec_float.h>
 
 struct SkinnedMesh;
+struct AnimNode;
 
 struct AnimationController {
   explicit AnimationController(SkinnedMesh* skinned_mesh);
+  virtual ~AnimationController();
 
-  void SetBlendAnims(
-      ozz::animation::Animation* blend_anim_A,
-      ozz::animation::Animation* blend_anim_B) {
-    m_blend_anim_A = blend_anim_A;
-    m_blend_anim_B = blend_anim_B;
-  }
-  void ResetAnims() {
-    m_anim_time_A = 0.f;
-    m_anim_time_B = 0.f;
-  }
-  void Update(float dt);
+  void ResetAnims();
+
+  // Creates a list of nodes where for node at index i for all inputs holds index > i.
+  void UpdateOrderedNodes();
+
+  // Updates all nodes.
+  void UpdateTime(float dt);
+
+  // Recursively evaluates all nodes.
   void Evaluate();
 
   void DrawDebugUi();
 
   float m_current_time;
-
-  ozz::animation::Animation* m_blend_anim_A;
-  ozz::animation::Animation* m_blend_anim_B;
-
-  float m_time_scale_A;
-  float m_time_scale_B;
-  float m_anim_time_A;
-  float m_anim_time_B;
-  float m_anim_ratio_A;
-  float m_anim_ratio_B;
-  bool m_override_ratio_A;
-  bool m_override_ratio_B;
-  float m_blend_weight;
-
-  ozz::vector<ozz::math::SoaTransform> m_local_matrices_A;
-  ozz::vector<ozz::math::SoaTransform> m_local_matrices_B;
-  ozz::vector<ozz::math::SoaTransform> m_local_matrices_blended;
-
-  ozz::animation::SamplingCache m_sampling_cache_A;
-  ozz::animation::SamplingCache m_sampling_cache_B;
+  bool m_paused;
 
   SkinnedMesh* m_skinned_mesh = nullptr;
+
+  AnimNode* m_output_node;
+
+  std::vector<AnimNode*> m_anim_nodes;
+  std::vector<AnimNode*> m_ordered_nodes;
 };
 
 #endif  //ANIMTESTBED_ANIMATIONCONTROLLER_H

src/Camera.c

@@ -42,8 +42,8 @@ inline void Camera_Init(Camera* camera) {
   camera->pitch = 10 * M_PI / 180.0f;
 
   memcpy(&camera->mtxView, &mtx_identity, sizeof(camera->mtxView));
-  Camera_CalcToMatrix(camera, &camera->mtxView);
-  Camera_CalcFromMatrix(camera, &camera->mtxView);
+  Camera_CalcToMatrix(camera, &camera->mtxView[0]);
+  Camera_CalcFromMatrix(camera, &camera->mtxView[0]);
 }
 
 void Camera_CalcFromMatrix(Camera* camera, float* mat) {
@@ -153,6 +153,6 @@ inline void Camera_Update(
       camera->vel[i] = camera->vel[i] * 0.1;
     }
 
-    Camera_CalcToMatrix(camera, &camera->mtxView);
+    Camera_CalcToMatrix(camera, &camera->mtxView[0]);
   }
 }

src/SkinnedMesh.cc

@@ -7,59 +7,6 @@
 #include <HandmadeMath.h>
 #include <imgui.h>
 
-#include "sokol_gfx.h"
-#include "util/sokol_gl.h"
-
-static void draw_vec(const ozz::math::SimdFloat4& vec) {
-  sgl_v3f(ozz::math::GetX(vec), ozz::math::GetY(vec), ozz::math::GetZ(vec));
-}
-
-static void draw_line(
-    const ozz::math::SimdFloat4& v0,
-    const ozz::math::SimdFloat4& v1) {
-  draw_vec(v0);
-  draw_vec(v1);
-}
-
-// this draws a wireframe 3d rhombus between the current and parent joints
-void SkinnedMesh::DrawJoint(int joint_index, int parent_joint_index) {
-  if (parent_joint_index < 0) {
-    return;
-  }
-
-  using namespace ozz::math;
-
-  const Float4x4& m0 = m_model_matrices[joint_index];
-  const Float4x4& m1 = m_model_matrices[parent_joint_index];
-
-  const SimdFloat4 p0 = m0.cols[3];
-  const SimdFloat4 p1 = m1.cols[3];
-  const SimdFloat4 ny = m1.cols[1];
-  const SimdFloat4 nz = m1.cols[2];
-
-  const SimdFloat4 len = SplatX(Length3(p1 - p0)) * simd_float4::Load1(0.1f);
-
-  const SimdFloat4 pmid = p0 + (p1 - p0) * simd_float4::Load1(0.66f);
-  const SimdFloat4 p2 = pmid + ny * len;
-  const SimdFloat4 p3 = pmid + nz * len;
-  const SimdFloat4 p4 = pmid - ny * len;
-  const SimdFloat4 p5 = pmid - nz * len;
-
-  sgl_c3f(1.0f, 1.0f, 0.0f);
-  draw_line(p0, p2);
-  draw_line(p0, p3);
-  draw_line(p0, p4);
-  draw_line(p0, p5);
-  draw_line(p1, p2);
-  draw_line(p1, p3);
-  draw_line(p1, p4);
-  draw_line(p1, p5);
-  draw_line(p2, p3);
-  draw_line(p3, p4);
-  draw_line(p4, p5);
-  draw_line(p5, p2);
-}
-
 SkinnedMesh::~SkinnedMesh() {
   while (m_animations.size() > 0) {
     ozz::animation::Animation* animation_ptr =
@@ -128,6 +75,7 @@ bool SkinnedMesh::LoadAnimation(const char* filename) {
 
   m_animations.push_back(animation_ptr);
   m_animation_names.push_back(filename);
+  m_animation_sync_track.push_back(SyncTrack());
 
   return true;
 }
@@ -141,20 +89,7 @@ void SkinnedMesh::SetCurrentAnimation(int index) {
   m_current_animation = m_animations[index];
 }
 
-//bool LoadMesh (const char* filename);
-
-void SkinnedMesh::EvalAnimation(float in_time) {
-  const float anim_duration = m_current_animation->duration();
-  float anim_ratio = fmodf((float)in_time / anim_duration, 1.0f);
-
-  // sample animation
-  ozz::animation::SamplingJob sampling_job;
-  sampling_job.animation = m_current_animation;
-  sampling_job.cache = &m_cache;
-  sampling_job.ratio = anim_ratio;
-  sampling_job.output = make_span(m_local_matrices);
-  sampling_job.Run();
-
+void SkinnedMesh::CalcModelMatrices() {
   // convert joint matrices from local to model space
   ozz::animation::LocalToModelJob ltm_job;
   ltm_job.skeleton = &m_skeleton;
@@ -163,39 +98,40 @@ void SkinnedMesh::EvalAnimation(float in_time) {
   ltm_job.Run();
 }
 
-void SkinnedMesh::DrawSkeleton() {
-  sgl_matrix_mode_modelview();
-  sgl_push_matrix();
-  hmm_mat4 scale_mat = HMM_Scale(HMM_Vec3(0.01f, 0.01f, 0.01f));
-  sgl_mult_matrix((const float*)&scale_mat);
-
-  const int num_joints = m_skeleton.num_joints();
-  ozz::span<const int16_t> joint_parents = m_skeleton.joint_parents();
-  sgl_begin_lines();
-  for (int joint_index = 0; joint_index < num_joints; joint_index++) {
-    DrawJoint(joint_index, joint_parents[joint_index]);
-  }
-  sgl_end();
-  sgl_pop_matrix();
-}
+void SkinnedMesh::DrawSkeleton() {}
 
 void SkinnedMesh::DrawDebugUi() {
   ImGui::Begin("SkinnedMesh");
 
-//  ImGui::Checkbox("Time override", &state.time.anim_ratio_ui_override);
+  ImGui::Text("Animations");
 
-  //  const float anim_duration = state.ozz->animation.duration();
-  //  if (!state.time.anim_ratio_ui_override) {
-  //    state.time.anim_ratio =
-  //        fmodf((float)state.time.absolute / anim_duration, 1.0f);
-  //  }
-  //  ImGui::SliderFloat("Time", &state.time.anim_ratio, 0.f, 1.f);
+  const char* items[255] = {0};
+  static int selected = -1;
+  for (int i = 0; i < m_animations.size(); i++) {
+    items[i] = m_animation_names[i].c_str();
+  }
 
-//  ImGui::Text(
-//      "Application average %.3f ms/frame (%.1f FPS)",
-//      1000.0f / ImGui::GetIO().Framerate,
-//      ImGui::GetIO().Framerate);
+  ImGui::Combo("Animation", &selected, items, m_animations.size());
+
+  ImGui::Text("Sync Track");
+  if (selected >= 0 && selected < m_animations.size()) {
+    m_animation_sync_track[selected].DrawDebugUi();
+    m_override_anim = selected;
+
+    ImGui::Checkbox("Override Animation", &m_sync_track_override);
+    if (m_sync_track_override) {
+      ImGui::SliderFloat("Ratio", &m_override_ratio, 0.f, 1.f);
+
+      ozz::animation::SamplingJob sampling_job;
+      sampling_job.animation = m_animations[selected];
+      sampling_job.cache = &m_cache;
+      sampling_job.ratio = m_override_ratio;
+      sampling_job.output = make_span(m_local_matrices);
+      if (!sampling_job.Run()) {
+        ozz::log::Err() << "Error sampling animation." << std::endl;
+      }
+    }
+  }
 
   ImGui::End();
-
 }

src/SkinnedMesh.h

@@ -9,6 +9,7 @@
 #include <cmath>   // fmodf
 #include <memory>  // std::unique_ptr, std::make_unique
 
+#include "SyncTrack.h"
 #include "ozz/animation/runtime/animation.h"
 #include "ozz/animation/runtime/local_to_model_job.h"
 #include "ozz/animation/runtime/sampling_job.h"
@@ -21,16 +22,22 @@
 #include "ozz/base/maths/vec_float.h"
 
 struct SkinnedMesh {
+  SkinnedMesh() : m_sync_track_override(false), m_override_anim(0.f) {}
   virtual ~SkinnedMesh();
+
   bool LoadSkeleton(const char* filename);
   bool LoadAnimation(const char* filename);
   //bool LoadMesh (const char* filename);
 
   void SetCurrentAnimation(int index);
-  const ozz::animation::Animation* GetCurrentAnimation() {return m_current_animation; };
-  float GetCurrentAnimationDuration() {return m_current_animation->duration(); };
+  const ozz::animation::Animation* GetCurrentAnimation() {
+    return m_current_animation;
+  };
+  float GetCurrentAnimationDuration() {
+    return m_current_animation->duration();
+  };
 
-  void EvalAnimation(float in_time);
+  void CalcModelMatrices();
   void DrawSkeleton();
   void DrawJoint(int joint_index, int parent_joint_index);
 
@@ -39,11 +46,16 @@ struct SkinnedMesh {
 
   ozz::vector<ozz::animation::Animation*> m_animations;
   std::vector<std::string> m_animation_names;
+  std::vector<SyncTrack> m_animation_sync_track;
   ozz::animation::Skeleton m_skeleton;
   ozz::animation::Animation* m_current_animation;
   ozz::animation::SamplingCache m_cache;
   ozz::vector<ozz::math::SoaTransform> m_local_matrices;
   ozz::vector<ozz::math::Float4x4> m_model_matrices;
+
+  bool m_sync_track_override;
+  int m_override_anim;
+  float m_override_ratio;
 };
 
 #endif  //ANIMTESTBED_SKINNEDMESH_H

src/SkinnedMeshRenderer.cc

@@ -0,0 +1,75 @@
+//
+// Created by martin on 16.11.21.
+//
+
+#include "SkinnedMeshRenderer.h"
+
+#include "sokol_gfx.h"
+#include "util/sokol_gl.h"
+#include "HandmadeMath.h"
+
+static void draw_vec(const ozz::math::SimdFloat4& vec) {
+  sgl_v3f(ozz::math::GetX(vec), ozz::math::GetY(vec), ozz::math::GetZ(vec));
+}
+
+static void draw_line(
+    const ozz::math::SimdFloat4& v0,
+    const ozz::math::SimdFloat4& v1) {
+  draw_vec(v0);
+  draw_vec(v1);
+}
+
+// this draws a wireframe 3d rhombus between the current and parent joints
+void draw_joint (const SkinnedMesh& skinned_mesh, int joint_index, int parent_joint_index) {
+  if (parent_joint_index < 0) {
+    return;
+  }
+
+  using namespace ozz::math;
+
+  const Float4x4& m0 = skinned_mesh.m_model_matrices[joint_index];
+  const Float4x4& m1 = skinned_mesh.m_model_matrices[parent_joint_index];
+
+  const SimdFloat4 p0 = m0.cols[3];
+  const SimdFloat4 p1 = m1.cols[3];
+  const SimdFloat4 ny = m1.cols[1];
+  const SimdFloat4 nz = m1.cols[2];
+
+  const SimdFloat4 len = SplatX(Length3(p1 - p0)) * simd_float4::Load1(0.1f);
+
+  const SimdFloat4 pmid = p0 + (p1 - p0) * simd_float4::Load1(0.66f);
+  const SimdFloat4 p2 = pmid + ny * len;
+  const SimdFloat4 p3 = pmid + nz * len;
+  const SimdFloat4 p4 = pmid - ny * len;
+  const SimdFloat4 p5 = pmid - nz * len;
+
+  sgl_c3f(1.0f, 1.0f, 0.0f);
+  draw_line(p0, p2);
+  draw_line(p0, p3);
+  draw_line(p0, p4);
+  draw_line(p0, p5);
+  draw_line(p1, p2);
+  draw_line(p1, p3);
+  draw_line(p1, p4);
+  draw_line(p1, p5);
+  draw_line(p2, p3);
+  draw_line(p3, p4);
+  draw_line(p4, p5);
+  draw_line(p5, p2);
+}
+
+void RenderSkinnedMesh (const SkinnedMesh& skinned_mesh) {
+  sgl_matrix_mode_modelview();
+  sgl_push_matrix();
+  hmm_mat4 scale_mat = HMM_Scale(HMM_Vec3(0.01f, 0.01f, 0.01f));
+  sgl_mult_matrix((const float*)&scale_mat);
+
+  const int num_joints = skinned_mesh.m_skeleton.num_joints();
+  ozz::span<const int16_t> joint_parents = skinned_mesh.m_skeleton.joint_parents();
+  sgl_begin_lines();
+  for (int joint_index = 0; joint_index < num_joints; joint_index++) {
+    draw_joint(skinned_mesh, joint_index, joint_parents[joint_index]);
+  }
+  sgl_end();
+  sgl_pop_matrix();
+}

src/SkinnedMeshRenderer.h

@@ -0,0 +1,12 @@
+//
+// Created by martin on 16.11.21.
+//
+
+#ifndef ANIMTESTBED_SKINNEDMESHRENDERER_H
+#define ANIMTESTBED_SKINNEDMESHRENDERER_H
+
+#include "SkinnedMesh.h"
+
+void RenderSkinnedMesh (const SkinnedMesh& skinned_mesh);
+
+#endif  //ANIMTESTBED_SKINNEDMESHRENDERER_H

src/SyncTrack.cc

@@ -0,0 +1,46 @@
+//
+// Created by martin on 19.11.21.
+//
+
+#include "SyncTrack.h"
+
+#include <imgui.h>
+
+#include <sstream>
+
+void SyncTrack::DrawDebugUi() {
+  ImGui::SliderFloat("duration", &m_duration, 0.001f, 10.f);
+
+  ImGui::Text("Marker");
+  ImGui::SameLine();
+  ImGui::Text("%d", m_num_intervals);
+  ImGui::SameLine();
+  if (ImGui::Button("+")) {
+    if (m_num_intervals < cSyncTrackMaxIntervals) {
+      m_num_intervals ++;
+    }
+  }
+  ImGui::SameLine();
+  if (ImGui::Button("-")) {
+    if (m_num_intervals > 0) {
+      m_num_intervals --;
+    }
+  }
+
+  ImGui::Text("Marker:");
+  for (int i = 0; i < m_num_intervals; i++) {
+    ImGui::Text("%2d:", i);
+    ImGui::SameLine();
+    std::ostringstream marker_stream;
+    marker_stream << i;
+    ImGui::SliderFloat(
+        marker_stream.str().c_str(),
+        &m_sync_markers[i],
+        0.f,
+        1.f);
+  }
+
+  if (ImGui::Button ("Update Intervals")) {
+    CalcIntervals();
+  }
+}

src/SyncTrack.h

@@ -0,0 +1,156 @@
+//
+// Created by martin on 19.11.21.
+//
+
+#ifndef ANIMTESTBED_SYNCTRACK_H
+#define ANIMTESTBED_SYNCTRACK_H
+
+#include <cassert>
+#include <cmath>
+
+constexpr int cSyncTrackMaxIntervals = 8;
+
+struct SyncTrack {
+  SyncTrack() : m_duration(0.f), m_num_intervals(0) {
+    for (int i = 0; i < cSyncTrackMaxIntervals; i++) {
+      m_sync_markers[i] = 0.f;
+      m_interval_ratio[i] = 0.f;
+      m_interval_ratio[i] = 0.f;
+    }
+  }
+
+  float m_duration;
+  int m_num_intervals;
+  float m_sync_markers[cSyncTrackMaxIntervals];
+  float m_interval_start[cSyncTrackMaxIntervals];
+  float m_interval_ratio[cSyncTrackMaxIntervals];
+
+  void CalcIntervals() {
+    if (m_num_intervals == 0) {
+      m_num_intervals = 1;
+      m_sync_markers[0] = 0.f;
+    }
+    for (int i = 0; i < m_num_intervals; i++) {
+      assert(m_sync_markers[i] >= 0.f && m_sync_markers[i] <= 1.0f);
+
+      int end_index = i < m_num_intervals - 1 ? i + 1 : 0;
+
+      m_interval_start[i] = m_sync_markers[i];
+      float interval_end = m_sync_markers[end_index];
+
+      if (interval_end < m_interval_start[i]) {
+        interval_end += 1.0f;
+      }
+
+      m_interval_ratio[i] = interval_end - m_interval_start[i];
+    }
+  }
+
+  float CalcSyncFromAbsTime(float abs_time) {
+    float sync_time = fmodf(abs_time, m_duration) / m_duration;
+
+    int interval_index = 0;
+    while (sync_time >= m_interval_ratio[interval_index]) {
+      sync_time -= m_interval_ratio[interval_index];
+      interval_index++;
+    }
+
+    return float(interval_index) + sync_time / m_interval_ratio[interval_index];
+  }
+
+  float CalcRatioFromSyncTime(float sync_time) {
+    float interval_ratio = fmodf(sync_time, 1.0f);
+    int interval = int(sync_time - interval_ratio);
+
+    return fmodf(
+        m_interval_start[interval]
+            + m_interval_ratio[interval] * interval_ratio,
+        1.0f);
+  }
+
+  bool operator==(const SyncTrack& other) const {
+    bool result = m_duration == other.m_duration
+                  && m_num_intervals == other.m_num_intervals;
+
+    if (!result) {
+      return false;
+    }
+
+    for (int i = 0; i < m_num_intervals; i++) {
+      if ((fabsf(m_interval_start[i] - other.m_interval_start[i]) > 1.0e-5)
+          || (fabsf(m_interval_ratio[i] - other.m_interval_ratio[i])
+              > 1.0e-5)) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  static SyncTrack CreateFromMarkers(
+      float duration,
+      int n_markers,
+      float markers[cSyncTrackMaxIntervals]) {
+    SyncTrack result;
+    result.m_duration = duration;
+    result.m_num_intervals = n_markers;
+    for (int i = 0; i < n_markers; i++) {
+      result.m_sync_markers[i] = markers[i];
+    }
+
+    result.CalcIntervals();
+
+    return result;
+  }
+
+  static SyncTrack
+  Blend(float weight, const SyncTrack& track_A, const SyncTrack& track_B) {
+    assert(track_A.m_num_intervals == track_B.m_num_intervals);
+
+    SyncTrack result;
+    result.m_num_intervals = track_A.m_num_intervals;
+
+    result.m_duration =
+        (1.0f - weight) * track_A.m_duration + weight * track_B.m_duration;
+
+    float interval_0_offset =
+        track_B.m_interval_start[0] - track_A.m_interval_start[0];
+    if (interval_0_offset > 0.5f) {
+      interval_0_offset = -fmodf(1.f - interval_0_offset, 1.0f);
+    } else if (interval_0_offset < -0.5) {
+      interval_0_offset = fmodf(1.f + interval_0_offset, 1.0f);
+    }
+
+    result.m_interval_start[0] = fmodf(
+        1.0 + (1.0f - weight) * track_A.m_interval_start[0]
+            + weight * (track_A.m_interval_start[0] + interval_0_offset),
+        1.0f);
+    result.m_sync_markers[0] = result.m_interval_start[0];
+
+    for (int i = 0; i < result.m_num_intervals; i++) {
+      float interval_duration_A = track_A.m_interval_ratio[i];
+      float interval_duration_B = track_B.m_interval_ratio[i];
+      result.m_interval_ratio[i] =
+          (1.0f - weight) * interval_duration_A + weight * interval_duration_B;
+
+      if (i < cSyncTrackMaxIntervals) {
+        result.m_interval_start[i + 1] =
+            result.m_interval_start[i] + result.m_interval_ratio[i];
+        if (result.m_interval_start[i + 1] > 1.0f) {
+          result.m_interval_start[i + 1] =
+              fmodf(result.m_interval_start[i + 1], 1.0f);
+        }
+
+        result.m_sync_markers[i + 1] = result.m_interval_start[i + 1];
+      }
+    }
+
+    assert (result.m_num_intervals < cSyncTrackMaxIntervals);
+
+    return result;
+  }
+
+  void DrawDebugUi();
+};
+
+#endif  //ANIMTESTBED_SYNCTRACK_H

src/main.cc

@@ -17,9 +17,10 @@
 #include "Camera.h"
 #include "SkinnedMesh.h"
 #include "GLFW/glfw3.h"
+#include "embedded_fonts.h"
 
-const int Width = 1024;
-const int Height = 768;
+const int Width = 2420;
+const int Height = 1480;
 const int MaxVertices = (1 << 16);
 const int MaxIndices = MaxVertices * 3;
 
@@ -47,6 +48,7 @@ static void draw_imgui(ImDrawData*);
 #include <memory>  // std::unique_ptr, std::make_unique
 
 #include "AnimationController.h"
+#include "SkinnedMeshRenderer.h"
 #include "ozz/animation/runtime/animation.h"
 #include "ozz/animation/runtime/local_to_model_job.h"
 #include "ozz/animation/runtime/sampling_job.h"
@@ -198,14 +200,40 @@ int main() {
   SkinnedMesh skinned_mesh;
   skinned_mesh.LoadSkeleton("../media/MixamoYBot-skeleton.ozz");
   skinned_mesh.LoadAnimation("../media/Idle-loop.ozz");
+
+  int anim_idx = 0;
+  float idle_markers[] = {0.f, 0.5};
+  skinned_mesh.m_animation_sync_track[anim_idx] = SyncTrack::CreateFromMarkers(skinned_mesh.m_animations[anim_idx]->duration(), 2, idle_markers);
+
+  anim_idx = 1;
   skinned_mesh.LoadAnimation("../media/Walking-loop.ozz");
+  float walking_markers[] = {0.293, 0.762};
+  skinned_mesh.m_animation_sync_track[anim_idx] = SyncTrack::CreateFromMarkers(skinned_mesh.m_animations[anim_idx]->duration(), 2, walking_markers);
+
+  anim_idx = 2;
   skinned_mesh.LoadAnimation("../media/RunningSlow-loop.ozz");
+  float running_slow_markers[] = {0.315, 0.834};
+  skinned_mesh.m_animation_sync_track[anim_idx] = SyncTrack::CreateFromMarkers(skinned_mesh.m_animations[anim_idx]->duration(), 2, running_slow_markers);
+
+  anim_idx = 3;
   skinned_mesh.LoadAnimation("../media/RunningFast-loop.ozz");
+  float running_fast_markers[] = {0.403, 0.818};
+  skinned_mesh.m_animation_sync_track[anim_idx] = SyncTrack::CreateFromMarkers(skinned_mesh.m_animations[anim_idx]->duration(), 2, running_fast_markers);
+
+  anim_idx = 4;
+  skinned_mesh.LoadAnimation("../media/Limping-loop.ozz");
+  float limping_markers[] = {0.757, 0.044};
+  skinned_mesh.m_animation_sync_track[anim_idx] = SyncTrack::CreateFromMarkers(skinned_mesh.m_animations[anim_idx]->duration(), 2, limping_markers);
+
+  anim_idx = 5;
+  skinned_mesh.LoadAnimation("../media/ZombieWalk-loop.ozz");
+  float zombiewalk_markers[] = {0.619, 0.};
+  skinned_mesh.m_animation_sync_track[anim_idx] = SyncTrack::CreateFromMarkers(skinned_mesh.m_animations[anim_idx]->duration(), 2, zombiewalk_markers);
+
   skinned_mesh.SetCurrentAnimation(0);
 
   AnimationController animation_controller (&skinned_mesh);
 
-//  state.ozz = std::make_unique<ozz_t>();
   state.time.factor = 1.0f;
 
   Camera_Init(&state.camera);
@@ -214,8 +242,24 @@ int main() {
   ImGui::CreateContext();
   ImGui::StyleColorsDark();
   ImGuiIO& io = ImGui::GetIO();
-  io.IniFilename = nullptr;
-  io.Fonts->AddFontDefault();
+  io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
+  io.IniFilename = "ATPImgui.ini";
+
+  ImGui::GetStyle().ScaleAllSizes(2.0);
+
+  //io.Fonts->AddFontDefault();
+  ImFontConfig font_config;
+  font_config.OversampleH = 4;
+  font_config.OversampleV = 4;
+  font_config.GlyphExtraSpacing.x = 1.0f;
+  io.Fonts->AddFontFromMemoryCompressedTTF(
+      //      roboto_medium_ttf_compressed_data,
+      //      roboto_medium_ttf_compressed_size,
+      droid_sans_ttf_compressed_data,
+      droid_sans_ttf_compressed_size,
+      28,
+      &font_config);
+
   io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB;
   io.KeyMap[ImGuiKey_LeftArrow] = GLFW_KEY_LEFT;
   io.KeyMap[ImGuiKey_RightArrow] = GLFW_KEY_RIGHT;
@@ -405,18 +449,23 @@ int main() {
 
 
     draw_grid();
+    ImGui::SetNextWindowPos(ImVec2 (600, 60), ImGuiCond_FirstUseEver);
+    ImGui::SetNextWindowSize(ImVec2 (300, 400), ImGuiCond_FirstUseEver);
     skinned_mesh.DrawDebugUi();
     animation_controller.DrawDebugUi();
 
-    animation_controller.Update(state.time.frame);
+    if (!skinned_mesh.m_sync_track_override) {
+      animation_controller.UpdateTime(state.time.frame);
       animation_controller.Evaluate();
+    }
+    skinned_mesh.CalcModelMatrices();
 
     sgl_defaults();
     sgl_matrix_mode_projection();
     sgl_load_matrix((const float*)&state.camera.mtxProj);
     sgl_matrix_mode_modelview();
     sgl_load_matrix((const float*)&state.camera.mtxView);
-    skinned_mesh.DrawSkeleton();
+    RenderSkinnedMesh(skinned_mesh);
 
     // 3. Show the ImGui test window. Most of the sample code is in ImGui::ShowDemoWindow()
     if (show_imgui_demo_window) {

tests/SyncTrackTests.cc

@@ -0,0 +1,202 @@
+//
+// Created by martin on 16.11.21.
+//
+
+#include "SyncTrack.h"
+#include "catch.hpp"
+
+TEST_CASE("Basic", "[SyncTrack]") {
+  SyncTrack track_A;
+  track_A.m_num_intervals = 2;
+  track_A.m_duration = 2.0;
+  track_A.m_interval_start[0] = 0.f;
+  track_A.m_interval_ratio[0] = 0.7;
+  track_A.m_interval_start[1] = 0.7f;
+  track_A.m_interval_ratio[1] = 0.3;
+
+  SyncTrack track_B;
+  track_B.m_num_intervals = 2;
+  track_B.m_duration = 1.5;
+  track_B.m_interval_start[0] = 0.0f;
+  track_B.m_interval_ratio[0] = 0.6;
+  track_B.m_interval_start[1] = 0.6f;
+  track_B.m_interval_ratio[1] = 0.4;
+
+  WHEN("Calculating sync time of track_B at 0.5 duration") {
+    float sync_time_at_0_75 =
+        track_B.CalcSyncFromAbsTime(0.5 * track_B.m_duration);
+    REQUIRE(sync_time_at_0_75 == Catch::Detail::Approx(0.83333));
+  }
+
+  WHEN("Calculating sync time of track_B at 0.6 duration") {
+    float sync_time_at_0_6 =
+        track_B.CalcSyncFromAbsTime(0.6 * track_B.m_duration);
+    REQUIRE(sync_time_at_0_6 == Catch::Detail::Approx(1.0));
+  }
+
+  WHEN("Calculating sync time of track_B at 0.7 duration") {
+    float sync_time_at_0_7 =
+        track_B.CalcSyncFromAbsTime(0.7 * track_B.m_duration);
+    REQUIRE(sync_time_at_0_7 == Catch::Detail::Approx(1.25));
+  }
+
+  WHEN("Calculating sync time of track_B at 0.0 duration") {
+    float sync_time_at_1_0 =
+        track_B.CalcSyncFromAbsTime(0.0 * track_B.m_duration);
+    REQUIRE(sync_time_at_1_0 == Catch::Detail::Approx(0.0));
+  }
+
+  WHEN("Calculating sync time of track_B at 1.0 duration") {
+    float sync_time_at_1_0 =
+        track_B.CalcSyncFromAbsTime(0.9999 * track_B.m_duration);
+    REQUIRE(sync_time_at_1_0 == Catch::Detail::Approx(2.0).epsilon(0.001f));
+  }
+
+  WHEN("Calculating ratio from sync time on track_A at 0.83333") {
+    float ratio = track_A.CalcRatioFromSyncTime(0.83333333);
+    REQUIRE(ratio == Catch::Detail::Approx(0.5833333));
+  }
+
+  WHEN("Calculating ratio from sync time on track_A at 0.83333") {
+    float ratio = track_A.CalcRatioFromSyncTime(1.25);
+    REQUIRE(ratio == Catch::Detail::Approx(0.775));
+  }
+
+  WHEN("Blending two synctracks with weight 0.") {
+    SyncTrack blended = SyncTrack::Blend(0.f, track_A, track_B);
+
+    THEN("Result must equal track_A") { REQUIRE(track_A == blended); }
+  }
+
+  WHEN("Blending two synctracks with weight 1.") {
+    SyncTrack blended = SyncTrack::Blend(1.f, track_A, track_B);
+
+    THEN("Result must equal track_B") { REQUIRE(track_B == blended); }
+  }
+}
+
+TEST_CASE("Sync Marker Interval Calculation", "[SyncTrack]") {
+  SyncTrack track_A;
+  track_A.m_num_intervals = 2;
+  track_A.m_duration = 2.0;
+  track_A.m_sync_markers[0] = 0.9;
+  track_A.m_sync_markers[1] = 0.2;
+
+  WHEN("Calculating intervals") {
+    track_A.CalcIntervals();
+
+    CHECK(track_A.m_interval_start[0] == Catch::Detail::Approx(0.9f));
+    CHECK(track_A.m_interval_ratio[0] == Catch::Detail::Approx(0.3f));
+
+    CHECK(track_A.m_interval_start[1] == Catch::Detail::Approx(0.2f));
+    CHECK(track_A.m_interval_ratio[1] == Catch::Detail::Approx(0.7f));
+
+    WHEN("Querying ratio at sync time at 1.001") {
+      float ratio = track_A.CalcRatioFromSyncTime(1.0001f);
+      CHECK(ratio == Catch::Detail::Approx(0.2).epsilon(0.001));
+    }
+
+    WHEN("Querying ratio at sync time at 1.001") {
+      float ratio = track_A.CalcRatioFromSyncTime(0.0001f);
+      CHECK(ratio == Catch::Detail::Approx(0.9).epsilon(0.001));
+    }
+
+    WHEN("Querying ratio at sync time at 1.9999") {
+      float ratio = track_A.CalcRatioFromSyncTime(0.9999f);
+      CHECK(ratio == Catch::Detail::Approx(0.2).epsilon(0.001));
+    }
+  }
+
+  WHEN("Blending sync track with 3 events") {
+    track_A.m_num_intervals = 3;
+    track_A.m_duration = 2.0;
+    track_A.m_sync_markers[0] = 0.;
+    track_A.m_sync_markers[1] = 0.3;
+    track_A.m_sync_markers[2] = 0.9;
+    track_A.CalcIntervals();
+
+    SyncTrack track_B;
+    track_B.m_num_intervals = 3;
+    track_B.m_duration = 1.5;
+    track_B.m_sync_markers[0] = 0.7;
+    track_B.m_sync_markers[1] = 0.9;
+    track_B.m_sync_markers[2] = 0.2;
+    track_B.CalcIntervals();
+
+    WHEN("Calculating A's durations") {
+      CHECK(track_A.m_interval_ratio[0] == Catch::Detail::Approx(0.3));
+      CHECK(track_A.m_interval_ratio[1] == Catch::Detail::Approx(0.6));
+      CHECK(track_A.m_interval_ratio[2] == Catch::Detail::Approx(0.1));
+    }
+
+    WHEN("Calculating B's durations") {
+      CHECK(track_B.m_interval_ratio[0] == Catch::Detail::Approx(0.2));
+      CHECK(track_B.m_interval_ratio[1] == Catch::Detail::Approx(0.3));
+      CHECK(track_B.m_interval_ratio[2] == Catch::Detail::Approx(0.5));
+    }
+
+    WHEN("Blending two synctracks with weight 0.") {
+      SyncTrack blended = SyncTrack::Blend(0.f, track_A, track_B);
+
+      THEN("Result must equal track_A") { REQUIRE(track_A == blended); }
+    }
+
+    WHEN("Blending two synctracks with weight 1.") {
+      SyncTrack blended = SyncTrack::Blend(1.f, track_A, track_B);
+
+      THEN("Result must equal track_B") { REQUIRE(track_B == blended); }
+    }
+
+    WHEN("Blending with weight 0.2") {
+      float weight = 0.2f;
+      SyncTrack blended = SyncTrack::Blend(weight, track_A, track_B);
+
+      REQUIRE(
+          blended.m_duration
+          == (1.0f - weight) * track_A.m_duration
+                 + weight * track_B.m_duration);
+      REQUIRE(
+          blended.m_interval_start[0]
+          == fmodf(
+              (1.0f - weight) * (track_A.m_interval_start[0] + 1.0f)
+                  + weight * (track_B.m_interval_start[0]),
+              1.0f));
+      REQUIRE(
+          blended.m_interval_ratio[1]
+          == (1.0f - weight) * (track_A.m_interval_ratio[1])
+                  + weight * (track_B.m_interval_ratio[1])
+              );
+      REQUIRE(
+          blended.m_interval_ratio[2]
+          == (1.0f - weight) * (track_A.m_interval_ratio[2])
+                 + weight * (track_B.m_interval_ratio[2])
+      );
+    }
+
+    WHEN("Inverted blending with weight 0.2") {
+      float weight = 0.2f;
+      SyncTrack blended = SyncTrack::Blend(weight, track_B, track_A);
+
+      REQUIRE(
+          blended.m_duration
+          == (1.0f - weight) * track_B.m_duration
+                 + weight * track_A.m_duration);
+      REQUIRE(
+          blended.m_interval_start[0]
+          == fmodf(
+              (1.0f - weight) * (track_B.m_interval_start[0])
+                  + weight * (track_A.m_interval_start[0] + 1.0f),
+              1.0f));
+      REQUIRE(
+          blended.m_interval_ratio[1]
+          == (1.0f - weight) * (track_B.m_interval_ratio[1])
+                 + weight * (track_A.m_interval_ratio[1])
+      );
+      REQUIRE(
+          blended.m_interval_ratio[2]
+          == (1.0f - weight) * (track_B.m_interval_ratio[2])
+                 + weight * (track_A.m_interval_ratio[2])
+      );
+    }
+  }
+}

tests/main.cc

@@ -0,0 +1,8 @@
+#define CATCH_CONFIG_RUNNER  // This tells Catch to provide a main() - only do this in one cpp file
+#include "catch.hpp"
+
+int main (int argc, char* argv[]) {
+  int result = Catch::Session().run(argc, argv);
+
+  return result;
+}