From f70dbc47ae9ab90a66506389ab3bb9996a53b461 Mon Sep 17 00:00:00 2001
From: Jeremy HU <huxingyi@msn.com>
Date: Sat, 10 Dec 2022 07:03:55 +1100
Subject: [PATCH] Implement bone vertex weights calculation

---
 application/sources/bone_generator.cc |  8 ++++
 dust3d/rig/bone_generator.cc          | 58 ++++++++++++++++++++++-----
 dust3d/rig/bone_generator.h           |  4 +-
 3 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/application/sources/bone_generator.cc b/application/sources/bone_generator.cc
index d6897c9a..3f9efda1 100644
--- a/application/sources/bone_generator.cc
+++ b/application/sources/bone_generator.cc
@@ -37,6 +37,14 @@ void BoneGenerator::process()
 
     for (const auto& it : m_snapshot->boneIdList) {
         Bone bone;
+        auto findBone = m_snapshot->bones.find(it);
+        if (findBone == m_snapshot->bones.end())
+            continue;
+        for (const auto& nodeIdString : dust3d::String::split(dust3d::String::valueOrEmpty(findBone->second, "jointNodeIdList"), ',')) {
+            if (nodeIdString.empty())
+                continue;
+            bone.joints.push_back(dust3d::Uuid(nodeIdString));
+        }
         addBone(dust3d::Uuid(it), bone);
     }
 
diff --git a/dust3d/rig/bone_generator.cc b/dust3d/rig/bone_generator.cc
index db389aac..02afdd97 100644
--- a/dust3d/rig/bone_generator.cc
+++ b/dust3d/rig/bone_generator.cc
@@ -127,11 +127,6 @@ void BoneGenerator::buildBoneJoints()
     }
 }
 
-void BoneGenerator::assignVerticesToBoneJoints()
-{
-    // TODO:
-}
-
 void BoneGenerator::groupBoneVertices()
 {
     for (size_t i = 0; i < m_vertexSourceNodes.size(); ++i) {
@@ -147,13 +142,53 @@ void BoneGenerator::groupBoneVertices()
     }
 }
 
+void BoneGenerator::calculateBoneVertexWeights(const Uuid& boneId, Bone& bone)
+{
+    auto findBoneVertices = m_boneVertices.find(boneId);
+    if (findBoneVertices == m_boneVertices.end())
+        return;
+
+    std::vector<std::unordered_set<size_t>> segments(bone.startPositions.size());
+
+    // Split bone vertices by joint position and forward direction
+    for (size_t jointIndex = 0; jointIndex + 1 < bone.startPositions.size(); ++jointIndex) {
+        const auto& nextJointPosition = bone.startPositions[jointIndex + 1];
+        auto forwardDirection = bone.forwardVectors[jointIndex].normalized();
+        for (const auto& vertex : findBoneVertices->second) {
+            const auto& vertexPosition = m_vertices[vertex];
+            if (Vector3::dotProduct(forwardDirection, (vertexPosition - nextJointPosition).normalized()) <= 0.0) {
+                segments[jointIndex].insert(vertex);
+            }
+        }
+    }
+
+    bone.vertexWeights.resize(bone.startPositions.size());
+    for (size_t jointIndex = 0; jointIndex < bone.startPositions.size(); ++jointIndex) {
+        for (const auto& it : segments[jointIndex])
+            bone.vertexWeights[jointIndex].push_back(VertexWeight { it, 1.0 });
+    }
+
+    // Calculate joint radius based on group all the boundary vertices,
+    // and use these vertices as points of sphere,
+    // boundary vertices means the edge connected these vertices in different bone vertex split
+    // Use m_triangles which contains all triangles to find the edges of vertices
+    // TODO:
+
+    // Weight vertex as normal when not in joint radius range
+    // TODO:
+
+    // Weight vertex as joint radius considered
+    // TODO:
+}
+
 void BoneGenerator::generate()
 {
     buildEdges();
     resolveVertexSources();
     groupBoneVertices();
     buildBoneJoints();
-    assignVerticesToBoneJoints();
+    for (auto& boneIt : m_boneMap)
+        calculateBoneVertexWeights(boneIt.first, boneIt.second);
     generateBonePreviews();
 }
 
@@ -228,9 +263,14 @@ void BoneGenerator::generateBonePreviews()
         auto findBone = m_boneMap.find(it.first);
         if (findBone == m_boneMap.end())
             continue;
-        const auto& color = s_colors[findBone->second.index % s_colors.size()];
-        for (const auto& vertexIndex : it.second)
-            vertexSkinColors[vertexIndex].push_back(color);
+        const auto& color = s_colors[(findBone->second.index) % s_colors.size()];
+        const auto& alternativeColor = s_colors[(findBone->second.index + s_colors.size() / 2) % s_colors.size()];
+        for (size_t jointIndex = 0; jointIndex < findBone->second.vertexWeights.size(); ++jointIndex) {
+            const auto& useColor = 0 == jointIndex % 2 ? color : alternativeColor;
+            for (const auto& vertexWeight : findBone->second.vertexWeights[jointIndex]) {
+                vertexSkinColors[vertexWeight.vertex].push_back(useColor);
+            }
+        }
     }
     std::vector<Color> bodyVertexColors(m_vertices.size());
     for (const auto& it : vertexSkinColors) {
diff --git a/dust3d/rig/bone_generator.h b/dust3d/rig/bone_generator.h
index 4e288304..1c948793 100644
--- a/dust3d/rig/bone_generator.h
+++ b/dust3d/rig/bone_generator.h
@@ -53,7 +53,7 @@ public:
         std::vector<Uuid> joints;
         std::vector<Vector3> startPositions;
         std::vector<Vector3> forwardVectors;
-        std::vector<VertexWeight> vertexWeights;
+        std::vector<std::vector<VertexWeight>> vertexWeights;
     };
 
     struct Node {
@@ -97,12 +97,12 @@ private:
     Uuid resolveVertexSourceByBreadthFirstSearch(size_t vertexIndex, std::unordered_set<size_t>& visited);
     void groupBoneVertices();
     void buildBoneJoints();
-    void assignVerticesToBoneJoints();
     void generateBonePreviews();
     void addBonePreviewTriangle(BonePreview& bonePreview,
         std::unordered_map<size_t, size_t>& oldToNewVertexMap,
         const std::vector<size_t>& triangle,
         const Color& color);
+    void calculateBoneVertexWeights(const Uuid& boneId, Bone& bone);
 };
 
 }