Implement some animation.

examples/skinning/README.md

@@ -2,7 +2,9 @@
 
 Example use CPU implementation of skinning for the explanation of how to process skin property in glTF format.
 
-OpenGL is used to display transformed vertex.
+Animation and skinning code is based on SacchaWillems' Vulkan-glTF-PBR: https://github.com/SaschaWillems/Vulkan-glTF-PBR
+
+OpenGL is still used to display renderings.
 
 ## Build on Linux and macOS
 

examples/skinning/main.cc

@@ -12,8 +12,8 @@
 #define GLFW_INCLUDE_GLU
 #include <GLFW/glfw3.h>
 
-#include "../common/trackball.h"
 #include "../common/matrix.h"
+#include "../common/trackball.h"
 
 #include "skinning.h"
 
@@ -49,7 +49,9 @@ float eye[3], lookat[3], up[3];
 
 GLFWwindow *window;
 
-typedef struct { GLuint vb; } GLBufferState;
+typedef struct {
+  GLuint vb;
+} GLBufferState;
 
 typedef struct {
   std::vector<GLuint> diffuseTex;  // for each primitive in mesh
@@ -65,16 +67,36 @@ typedef struct {
   size_t count;  // byte count
 } GLCurvesState;
 
-
-// Stores vertex position transformed by skinning 
+// Stores vertex position transformed by skinning
 typedef struct {
-  std::vector<float> positions; // float4
+  std::vector<float> positions;  // float4
 } SkinnedMesh;
 
 typedef struct {
-  std::vector<example::mat4> inverseBindMatrices; // mat44
+  std::vector<example::mat4> inverseBindMatrices;  // mat44
 } SkinningMatrices;
 
+struct AnimationChannel {
+  enum PathType { TRANSLATION, ROTATION, SCALE };
+  PathType path;
+  // Node *node;
+  uint32_t samplerIndex;
+};
+
+struct AnimationSampler {
+  enum InterpolationType { LINEAR, STEP, CUBICSPLINE };
+  InterpolationType interpolation;
+  std::vector<float> inputs;
+  std::vector<example::vec4> outputsVec4;
+};
+
+struct Animation {
+  std::string name;
+  std::vector<AnimationSampler> samplers;
+  std::vector<AnimationChannel> channels;
+  float start = std::numeric_limits<float>::max();
+  float end = std::numeric_limits<float>::min();
+};
 
 std::map<int, GLBufferState> gBufferState;
 std::map<std::string, GLMeshState> gMeshState;
@@ -545,7 +567,8 @@ static void DrawMesh(tinygltf::Model &model, const tinygltf::Mesh &mesh) {
     for (; it != itEnd; it++) {
       assert(it->second >= 0);
       const tinygltf::Accessor &accessor = model.accessors[it->second];
-      const tinygltf::BufferView &bufferView = model.bufferViews[accessor.bufferView];
+      const tinygltf::BufferView &bufferView =
+          model.bufferViews[accessor.bufferView];
 
       if (bufferView.target == 0) {
         continue;
@@ -571,12 +594,13 @@ static void DrawMesh(tinygltf::Model &model, const tinygltf::Mesh &mesh) {
           (it->first.compare("TEXCOORD_0") == 0)) {
         if (gGLProgramState.attribs[it->first] >= 0) {
           // Compute byteStride from Accessor + BufferView combination.
-          int byteStride = accessor.ByteStride(model.bufferViews[accessor.bufferView]);
+          int byteStride =
+              accessor.ByteStride(model.bufferViews[accessor.bufferView]);
           assert(byteStride != -1);
           glVertexAttribPointer(gGLProgramState.attribs[it->first], size,
-                                accessor.componentType, accessor.normalized ? GL_TRUE : GL_FALSE,
-                                byteStride,
-                                BUFFER_OFFSET(accessor.byteOffset));
+                                accessor.componentType,
+                                accessor.normalized ? GL_TRUE : GL_FALSE,
+                                byteStride, BUFFER_OFFSET(accessor.byteOffset));
           CheckErrors("vertex attrib pointer");
           glEnableVertexAttribArray(gGLProgramState.attribs[it->first]);
           CheckErrors("enable vertex attrib array");
@@ -742,8 +766,9 @@ static void PrintNodes(const tinygltf::Scene &scene) {
   }
 }
 
-static void ConstructNodeMatrix(const tinygltf::Node &node, example::mat4 *xform) {
-
+#if 0
+static void ConstructNodeMatrix(const tinygltf::Node &node,
+                                example::mat4 *xform) {
   if (node.matrix.size() == 16) {
     for (size_t j = 0; j < 4; j++) {
       for (size_t i = 0; i < 4; i++) {
@@ -779,45 +804,54 @@ static void ConstructNodeMatrix(const tinygltf::Node &node, example::mat4 *xform
   }
 
   example::BuildTransofrmMatrix(translation, rotation, scale, xform);
-
 }
 
 //
-// Hierarchically evalute skining matrix
+// Hierarchically evalute skining
 //
-static void ApplySkinningToMesh(const tinygltf::model &model, const tinygltf::Node &node, example::mat4 &parent_xform, std::vector<SkinnedMesh> *skinned_meshes) {
-  example::mat4 xform = parent_xform;
+static void ApplySkinningToMesh(const tinygltf::Model &model,
+                                const tinygltf::Node &node,
+                                example::mat4 &parent_xform,
+                                std::vector<SkinnedMesh> *skinned_meshes) {
+  example::mat4 node_xform;
+  ConstructNodeMatrix(node, &node_xform);
 
   if (node.mesh) {
     if (node.skin) {
     }
   }
 
+  example::mat4 xform;
+  Matrix::Mult(xform.m, parent_xform.m, node_xform.m);
+
   for (auto &child : node.children) {
-    ApplySkinningToMesh(model.nodes[child], xform, skinned_meshes);
+    ApplySkinningToMesh(model, model.nodes[child], xform, skinned_meshes);
   }
 }
+#endif
 
 //
 // Read inverseBindMatricies for each skin
 //
-static void SetupSkinningMatrices(const tinygltf::Model &model, std::map<int, SkinningMatrices> &skinning_matrices)
-{
+static void SetupSkinningMatrices(
+    const tinygltf::Model &model,
+    std::map<int, SkinningMatrices> &skinning_matrices) {
   for (size_t s = 0; s < model.skins.size(); s++) {
     const tinygltf::Skin &skin = model.skins[s];
 
     if (skin.inverseBindMatrices > -1) {
-
       if (skin.joints.size() > 0) {
-
-        const tinygltf::Accessor &accessor = model.accessors[skin.inverseBindMatrices];
+        const tinygltf::Accessor &accessor =
+            model.accessors[skin.inverseBindMatrices];
         assert(accessor.type == TINYGLTF_TYPE_MAT4);
 
-        const tinygltf::BufferView &bufferView = model.bufferViews[accessor.bufferView];
+        const tinygltf::BufferView &bufferView =
+            model.bufferViews[accessor.bufferView];
 
         const tinygltf::Buffer &buffer = model.buffers[bufferView.buffer];
 
-        const float *ptr = reinterpret_cast<const float *>(buffer.data.data() + accessor.byteOffset + bufferView.byteOffset);
+        const float *ptr = reinterpret_cast<const float *>(
+            buffer.data.data() + accessor.byteOffset + bufferView.byteOffset);
         std::cout << "count = " << accessor.count << std::endl;
 
         std::vector<example::mat4> inverse_bind_matrices(accessor.count);
@@ -830,14 +864,11 @@ static void SetupSkinningMatrices(const tinygltf::Model &model, std::map<int, Sk
 
           std::cout << "j[" << j << "] = " << std::endl;
           Matrix::Print(inverse_bind_matrices[j].m);
-        
         }
 
         skinning_matrices[s].inverseBindMatrices = inverse_bind_matrices;
-
       }
     }
-    
   }
 }
 
@@ -862,7 +893,8 @@ int main(int argc, char **argv) {
   bool ret = false;
   if (ext.compare("glb") == 0) {
     // assume binary glTF.
-    ret = loader.LoadBinaryFromFile(&model, &err, &warn, input_filename.c_str());
+    ret =
+        loader.LoadBinaryFromFile(&model, &err, &warn, input_filename.c_str());
   } else {
     // assume ascii glTF.
     ret = loader.LoadASCIIFromFile(&model, &err, &warn, input_filename.c_str());
@@ -886,10 +918,11 @@ int main(int argc, char **argv) {
     std::cerr << "Scene is empty" << std::endl;
     return EXIT_FAILURE;
   }
-  
+
   std::cout << "defaultScene = " << model.defaultScene << std::endl;
   if (model.defaultScene >= int(model.scenes.size())) {
-    std::cerr << "Invalid defualtScene value : " << model.defaultScene << std::endl;
+    std::cerr << "Invalid defualtScene value : " << model.defaultScene
+              << std::endl;
     return EXIT_FAILURE;
   }
 

examples/skinning/skinning.cc

@@ -1,19 +1,49 @@
 #include "skinning.h"
 
 #include "../common/matrix.h"
-#include "../common/trackball.h" // for quaternion
+#include "../common/trackball.h"  // for quaternion
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Weverything"
+#endif
+
+#define HANDMADE_MATH_IMPLEMENTATION
+#include "HandmadeMath.h"
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
 
-#include <cstring>
 #include <cassert>
+#include <cstring>
 
 namespace example {
 
-void BuildTransofrmMatrix(
-  const float translate[3],
-  const float rotation[4], // as quaternion in glTF
-  const float scale[3],
-  mat4 *transform_matrix) {
+struct Node {
 
+  float translation[3] = {0.0f, 0.0f, 0.0f};
+  float scale[4] = {1.0f, 1.0f, 1.0f};
+  float rotation[4] = {0.0f, 0.0f, 0.0f, 1.0f};
+
+
+  void update() {
+  }
+};
+
+static inline vec4 mix(vec4 x, vec4 y, float a) {
+  vec4 v;
+  v.f[0] = (1.0f - a) * x.f[0] + a * y.f[0];
+  v.f[1] = (1.0f - a) * x.f[1] + a * y.f[1];
+  v.f[2] = (1.0f - a) * x.f[2] + a * y.f[2];
+  v.f[3] = (1.0f - a) * x.f[3] + a * y.f[3];
+
+  return v;
+}
+
+void BuildTransofrmMatrix(const float translate[3],
+                          const float rotation[4],  // as quaternion in glTF
+                          const float scale[3], mat4 *transform_matrix) {
   float T[4][4];
   T[0][0] = 1.0f;
   T[0][1] = 0.0f;
@@ -68,11 +98,10 @@ void BuildTransofrmMatrix(
 }
 
 void ComputeJointMatrices(
-  const std::vector<mat4> global_transform_of_nodes,
-  const std::vector<mat4> global_transform_of_joint_nodes,
-  const std::vector<mat4> inverse_bind_matrix_for_joints,
-  std::vector<mat4> *output_joint_matrices) {
-
+    const std::vector<mat4> global_transform_of_nodes,
+    const std::vector<mat4> global_transform_of_joint_nodes,
+    const std::vector<mat4> inverse_bind_matrix_for_joints,
+    std::vector<mat4> *output_joint_matrices) {
   const size_t n = global_transform_of_nodes.size();
 
   output_joint_matrices->resize(n);
@@ -84,21 +113,18 @@ void ComputeJointMatrices(
     mat4 g_joint = global_transform_of_joint_nodes[i];
     mat4 inverse_bind_matrix = inverse_bind_matrix_for_joints[i];
 
-    float a[4][4]; // temp matrix
+    float a[4][4];  // temp matrix
     Matrix::Mult(a, g_joint.m, inverse_bind_matrix.m);
 
     Matrix::Mult((*output_joint_matrices)[i].m, g_inv.m, a);
   }
 }
 
-
 void Skining(const std::vector<float> vertices,
              const std::vector<float> weights, const std::vector<size_t> joints,
              const size_t num_skinning_weights,
-             const std::vector<mat4> joint_matrices,
-             const float t,
+             const std::vector<mat4> joint_matrices, const float t,
              std::vector<float> *skinned_vertices) {
-
   assert((vertices.size() % 4) == 0);
   const size_t num_vertices = vertices.size() / 4;
 
@@ -135,7 +161,6 @@ void Skining(const std::vector<float> vertices,
         M.m[j][i] = I.m[j][i] * t + (1.0f - t) * skin_mat.m[j][i];
       }
     }
-    
 
     float vtx[4];
     vtx[0] = vertices[4 * v + 0];
@@ -145,8 +170,83 @@ void Skining(const std::vector<float> vertices,
 
     float ret[4];
     Matrix::MultV4(ret, M.m, vtx);
-  } 
+  }
 }
 
+void UpdateAnimation(std::vector<Animation> &animations, uint32_t index,
+                     float time, std::vector<Node*> &nodes) {
+  if (index > uint32_t(animations.size() - 1)) {
+    return;
+  }
 
-} // namespace example
+  const Animation &animation = animations[index];
+
+  bool updated = false;
+  for (auto &channel : animation.channels) {
+    const AnimationSampler &sampler = animation.samplers[channel.samplerIndex];
+    if (sampler.inputs.size() > sampler.outputsVec4.size()) {
+      continue;
+    }
+
+    // TODO(LTE): support interpolation other than LINEAR
+    for (size_t i = 0; i < sampler.inputs.size() - 1; i++) {
+      if ((time >= sampler.inputs[i]) && (time <= sampler.inputs[i + 1])) {
+        float u = std::max(0.0f, time - sampler.inputs[i]) /
+                  (sampler.inputs[i + 1] - sampler.inputs[i]);
+        if (u <= 1.0f) {
+          switch (channel.path) {
+            case AnimationChannel::PathType::TRANSLATION: {
+              example::vec4 trans =
+                  mix(sampler.outputsVec4[i], sampler.outputsVec4[i + 1], u);
+              channel.node->translation[0] = trans.f[0];
+              channel.node->translation[1] = trans.f[1];
+              channel.node->translation[2] = trans.f[2];
+              // drop w
+              break;
+            }
+            case AnimationChannel::PathType::SCALE: {
+              example::vec4 scale =
+                  mix(sampler.outputsVec4[i], sampler.outputsVec4[i + 1], u);
+              channel.node->scale[0] = scale.f[0];
+              channel.node->scale[1] = scale.f[1];
+              channel.node->scale[2] = scale.f[2];
+              break;
+            }
+            case AnimationChannel::PathType::ROTATION: {
+
+              hmm_quaternion q1 = HMM_Quaternion(
+               sampler.outputsVec4[i].f[0],
+               sampler.outputsVec4[i].f[1],
+               sampler.outputsVec4[i].f[2],
+               sampler.outputsVec4[i].f[3]);
+
+              hmm_quaternion q2 = HMM_Quaternion(
+               sampler.outputsVec4[i + 1].f[0],
+               sampler.outputsVec4[i + 1].f[1],
+               sampler.outputsVec4[i + 1].f[2],
+               sampler.outputsVec4[i + 1].f[3]);
+
+              hmm_quaternion q = HMM_NormalizeQuaternion(HMM_Slerp(q1, u, q2));
+
+              channel.node->rotation[0] = q.Elements[0];
+              channel.node->rotation[1] = q.Elements[1];
+              channel.node->rotation[2] = q.Elements[2];
+              channel.node->rotation[3] = q.Elements[3];
+
+              break;
+            }
+          }
+          updated = true;
+        }
+      }
+    }
+  }
+
+  if (updated) {
+    for (auto &node : nodes) {
+      node->update();
+    }
+  }
+}
+
+}  // namespace example

examples/skinning/skinning.h

@@ -3,6 +3,9 @@
 
 #include <vector>
 #include <cstddef>
+#include <cstdint>
+#include <string>
+#include <limits>
 
 namespace example {
 
@@ -10,6 +13,36 @@ struct mat4 {
   float m[4][4];
 };
 
+struct vec4 {
+  float f[4];
+};
+
+// glTF node
+struct Node;
+
+
+struct AnimationChannel {
+  enum PathType { TRANSLATION, ROTATION, SCALE };
+  PathType path;
+  Node *node;
+  uint32_t samplerIndex;
+};
+
+struct AnimationSampler {
+  enum InterpolationType { LINEAR, STEP, CUBICSPLINE };
+  InterpolationType interpolation;
+  std::vector<float> inputs;
+  std::vector<example::vec4> outputsVec4;
+};
+
+struct Animation {
+  std::string name;
+  std::vector<AnimationSampler> samplers;
+  std::vector<AnimationChannel> channels;
+  float start = std::numeric_limits<float>::max();
+  float end = std::numeric_limits<float>::min();
+};
+
 ///
 /// Utility function to build transformation matrix from translate/rotation/scale
 ///