From 9e4f9977e0e50f38293436d753279d17c1815c2d Mon Sep 17 00:00:00 2001
From: Tyler Fox <tyler@blur.com>
Date: Fri, 16 Aug 2024 17:03:38 -0700
Subject: [PATCH] Add the closed attribute

---
 src/twistMultiTangentNode.cpp | 55 ++++++++++++++++++++++++++++-------
 src/twistMultiTangentNode.h   |  1 +
 2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/src/twistMultiTangentNode.cpp b/src/twistMultiTangentNode.cpp
index 933e495..ca94d1a 100644
--- a/src/twistMultiTangentNode.cpp
+++ b/src/twistMultiTangentNode.cpp
@@ -69,6 +69,7 @@ MObject TwistMultiTangentNode::aVertData;
 MObject TwistMultiTangentNode::aStartTension;
 MObject TwistMultiTangentNode::aEndTension;
 MObject TwistMultiTangentNode::aMaxVertices;
+MObject TwistMultiTangentNode::aClosed;
 
 // outputs
 MObject TwistMultiTangentNode::aInTanX;
@@ -203,9 +204,14 @@ MStatus TwistMultiTangentNode::initialize()
     num_attr.setKeyable(true);
     num_attr.setStorable(true);
     num_attr.setMin(2);
-
     addAttribute(aMaxVertices);
 
+    aClosed = num_attr.create("closed", "cl", MFnNumericData::kBoolean, false, &status);
+    num_attr.setKeyable(true);
+    num_attr.setStorable(true);
+    num_attr.setMin(2);
+    addAttribute(aClosed);
+
     aInTanX =
         unit_attr.create("inVertTanX", "ivx", MFnUnitAttribute::kDistance, 0.0, &status);
     unit_attr.setKeyable(false);
@@ -305,6 +311,7 @@ MStatus TwistMultiTangentNode::initialize()
     ins.push_back(&aStartTension);
     ins.push_back(&aEndTension);
     ins.push_back(&aMaxVertices);
+    ins.push_back(&aClosed);
     ins.push_back(&aVertMat);
     ins.push_back(&aInParentInv);
     ins.push_back(&aOutParentInv);
@@ -435,7 +442,7 @@ buildVertMatTangent(double nextLegLen, double preLegLen, MVector &nextLegNrm, MV
     return ((bin ^ preLegNrm) + (bin ^ nextLegNrm)).normal();
 }
 
-void buildSmoothMats(std::vector<TanData> &dat, double startTension, double endTension)
+void buildSmoothMats(std::vector<TanData> &dat, double startTension, double endTension, bool closed)
 {
     for (size_t i = 1; i + 1 < dat.size(); ++i) {
         auto &cur = dat[i];
@@ -449,16 +456,34 @@ void buildSmoothMats(std::vector<TanData> &dat, double startTension, double endT
         cur.inTan.smoothTan = -tan * preLegLen;
         cur.outTan.smoothTan = tan * nextLegLen;
     }
-    dat[0].outTan.smoothTan = (dat[1].tfm + dat[1].inTan.smoothTan * startTension - dat[0].tfm) *
-                              (dat[0].outTan.weight / 2);
-    dat[0].smoothMat = buildMat(dat[0].tfm, dat[0].norm, dat[0].outTan.smoothTan.normal());
 
-    size_t s = dat.size();
-    dat[s - 1].inTan.smoothTan =
-        (dat[s - 2].tfm + dat[s - 2].outTan.smoothTan * startTension - dat[s - 1].tfm) *
-        (dat[s - 1].inTan.weight / 2);
+    if (closed){
+        auto &start = dat[0];
+        auto &end = dat[dat.size() - 1];
 
-    dat[s - 1].smoothMat = buildMat(dat[s - 1].tfm, dat[s - 1].norm, -dat[s - 1].inTan.smoothTan.normal());
+        MVector tan = buildVertMatTangent(
+            start.outTan.legLen, end.inTan.legLen, start.outTan.normLeg, end.inTan.normLeg
+        );
+        start.smoothMat = buildMat(start.tfm, start.norm, tan);
+        end.smoothMat = start.smoothMat;
+        double preLegLen = end.inTan.legLen * end.inTan.weight / 3;
+        double nextLegLen = start.outTan.legLen * start.outTan.weight / 3;
+
+        end.inTan.smoothTan = -tan * preLegLen;
+        start.outTan.smoothTan = tan * nextLegLen;
+    }
+    else{
+        dat[0].outTan.smoothTan = (dat[1].tfm + dat[1].inTan.smoothTan * startTension - dat[0].tfm) *
+                                (dat[0].outTan.weight / 2);
+        dat[0].smoothMat = buildMat(dat[0].tfm, dat[0].norm, dat[0].outTan.smoothTan.normal());
+
+        size_t s = dat.size();
+        dat[s - 1].inTan.smoothTan =
+            (dat[s - 2].tfm + dat[s - 2].outTan.smoothTan * startTension - dat[s - 1].tfm) *
+            (dat[s - 1].inTan.weight / 2);
+
+        dat[s - 1].smoothMat = buildMat(dat[s - 1].tfm, dat[s - 1].norm, -dat[s - 1].inTan.smoothTan.normal());
+    }
 }
 
 void buildLinearTangents(std::vector<TanData> &dat)
@@ -521,6 +546,7 @@ MStatus TwistMultiTangentNode::compute(const MPlug &plug, MDataBlock &data)
     double startTension = data.inputValue(aStartTension).asDouble();
     double endTension = data.inputValue(aEndTension).asDouble();
     int maxVertices = data.inputValue(aMaxVertices).asInt();
+    bool closed = data.inputValue(aClosed).asBool();
 
     icount = (icount < maxVertices) ? icount : (unsigned int)maxVertices;
     if (icount < 2) {
@@ -576,6 +602,13 @@ MStatus TwistMultiTangentNode::compute(const MPlug &plug, MDataBlock &data)
         tanData.push_back(std::move(dat));
     }
 
+    if (closed){
+        auto &start = tanData[0];
+        auto &end = tanData[tanData.size() - 1];
+        start.inTan = end.inTan;
+        end.outTan = start.outTan;
+    }
+
     for (size_t i = 1; i < tanData.size(); ++i) {
         auto &prev = tanData[i - 1];
         auto &cur = tanData[i];
@@ -592,7 +625,7 @@ MStatus TwistMultiTangentNode::compute(const MPlug &plug, MDataBlock &data)
     tanData[0].inTan.legLen = 0.0;
     tanData[tanData.size() - 1].outTan.legLen = 0.0;
 
-    buildSmoothMats(tanData, startTension, endTension);
+    buildSmoothMats(tanData, startTension, endTension, closed);
     buildLinearTangents(tanData);
     buildDoneTangents(tanData);
 
diff --git a/src/twistMultiTangentNode.h b/src/twistMultiTangentNode.h
index 931c989..0fd3451 100644
--- a/src/twistMultiTangentNode.h
+++ b/src/twistMultiTangentNode.h
@@ -57,6 +57,7 @@ class TwistMultiTangentNode : public MPxNode {
     static MObject aStartTension;
     static MObject aEndTension;
     static MObject aMaxVertices;
+    static MObject aClosed;
 
 	// outputs
     static MObject aInTanX;