From a7f22efd1b4cc7390198838a8939eb085ab680b7 Mon Sep 17 00:00:00 2001
From: Jeremy Hu <huxingyi@msn.com>
Date: Sat, 18 Jan 2020 15:31:10 +0930
Subject: [PATCH] Optimize cloth simulation

---
 src/meshgenerator.cpp       |  5 ++++-
 src/simulateclothmeshes.cpp | 15 +++++++++++----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/meshgenerator.cpp b/src/meshgenerator.cpp
index 694cee63..797c8ee0 100644
--- a/src/meshgenerator.cpp
+++ b/src/meshgenerator.cpp
@@ -873,14 +873,17 @@ bool MeshGenerator::componentRemeshed(const std::map<QString, QString> *componen
 {
     if (nullptr == component)
         return false;
+    bool isCloth = false;
     if (ComponentLayer::Cloth == ComponentLayerFromString(valueOfKeyInMapOrEmpty(*component, "layer").toUtf8().constData())) {
         if (nullptr != polyCountValue)
             *polyCountValue = PolyCountToValue(PolyCount::UltraHighPoly);
-        return true;
+        isCloth = true;
     }
     auto polyCount = PolyCountFromString(valueOfKeyInMapOrEmpty(*component, "polyCount").toUtf8().constData());
     if (nullptr != polyCountValue)
         *polyCountValue = PolyCountToValue(polyCount);
+    if (isCloth)
+        return true;
     return polyCount != PolyCount::Original;
 }
 
diff --git a/src/simulateclothmeshes.cpp b/src/simulateclothmeshes.cpp
index c672e5c6..4df1c264 100644
--- a/src/simulateclothmeshes.cpp
+++ b/src/simulateclothmeshes.cpp
@@ -36,19 +36,26 @@ public:
         
         std::vector<QVector3D> &filteredClothVertices = clothMesh->vertices;
         std::vector<QVector3D> externalForces;
+        std::vector<QVector3D> postProcessDirections;
         const auto &clothForce = clothMesh->clothForce;
-        float clothOffset = 0.015f + (clothMesh->clothOffset * 0.05f);
+        float clothOffset = 0.01f + (clothMesh->clothOffset * 0.05f);
         if (ClothForce::Centripetal == clothForce) {
             externalForces.resize(filteredClothVertices.size());
+            postProcessDirections.resize(filteredClothVertices.size());
             for (size_t i = 0; i < filteredClothFaces.size(); ++i) {
                 const auto &face = filteredClothFaces[i];
                 auto faceForceDirection = -polygonNormal(filteredClothVertices, face);
                 for (const auto &vertex: face)
                     externalForces[vertex] += faceForceDirection;
             }
-            for (auto &it: externalForces)
-                it = (it.normalized() + QVector3D(0.0f, -1.0f, 0.0f)).normalized();
+            for (size_t i = 0; i < externalForces.size(); ++i) {
+                auto &it = externalForces[i];
+                it.normalize();
+                postProcessDirections[i] = it * clothOffset;
+                it = (it + QVector3D(0.0f, -1.0f, 0.0f)).normalized();
+            }
         } else {
+            postProcessDirections.resize(filteredClothVertices.size(), QVector3D(0.0f, -1.0f, 0.0f) * clothOffset);
             externalForces.resize(filteredClothVertices.size(), QVector3D(0.0f, -1.0f, 0.0f));
         }
         ClothSimulator clothSimulator(filteredClothVertices,
@@ -62,7 +69,7 @@ public:
             clothSimulator.step();
         clothSimulator.getCurrentVertices(&filteredClothVertices);
         for (size_t i = 0; i < filteredClothVertices.size(); ++i) {
-            filteredClothVertices[i] -= externalForces[i] * clothOffset;
+            filteredClothVertices[i] -= postProcessDirections[i];
         }
     }
     void operator()(const tbb::blocked_range<size_t> &range) const