Merge pull request #193 from Colorbleed/skinUsePeBindMatrixAndMesh

Use skinCluster input shape and preBindMatrix instead of initial values time
iimachines · Oct 25, 2022 · 159fbd3 · 159fbd3
2 parents e52b221 + f7eb42b
commit 159fbd3
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Showing 5 changed files with 62 additions and 9 deletions.
diff --git a/src/Arguments.cpp b/src/Arguments.cpp
@@ -40,6 +40,7 @@ const auto animationClipStartTime = "ast";
 const auto animationClipEndTime = "aet";
 
 const auto initialValuesTime = "ivt";
+const auto skinUsePreBindMatrixAndMesh = "pbm";
 
 const auto redrawViewport = "rvp";
 
@@ -172,6 +173,7 @@ SyntaxFactory::SyntaxFactory() {
     registerFlag(ss, flag::animationClipEndTime, "animationClipEndTime", true, kTime);
 
     registerFlag(ss, flag::initialValuesTime, "initialValuesTime", kTime);
+    registerFlag(ss, flag::skinUsePreBindMatrixAndMesh, "skinUsePreBindMatrixAndMesh", kNoArg);
 
     registerFlag(ss, flag::meshPrimitiveAttributes, "meshPrimitiveAttributes", kString);
     registerFlag(ss, flag::blendPrimitiveAttributes, "blendPrimitiveAttributes", kString);
@@ -565,6 +567,7 @@ Arguments::Arguments(const MArgList &args, const MSyntax &syntax) {
 
     initialValuesTime = clipCount > 0 ? MTime(0, MTime::kSeconds) : MAnimControl::currentTime();
     adb.optional(flag::initialValuesTime, initialValuesTime);
+    skinUsePreBindMatrixAndMesh = adb.isFlagSet(flag::skinUsePreBindMatrixAndMesh);
 
     const auto fpsCount = adb.flagUsageCount(flag::animationClipFrameRate);
 

diff --git a/src/Arguments.h b/src/Arguments.h
@@ -220,6 +220,12 @@ class Arguments {
      */
     MTime initialValuesTime;
 
+    /**
+     * Use the skinCluster's preBindMatrix values and input mesh for initial base bind 
+     * instead of the visible output mesh from at initialValuesTime.
+     */
+    bool skinUsePreBindMatrixAndMesh = false;
+
     /** Redraw the viewport while exporting? True in debug builds by default,
      * false otherwise (for speed) */
 #ifdef _DEBUG

diff --git a/src/MeshSkeleton.cpp b/src/MeshSkeleton.cpp
@@ -48,8 +48,23 @@ MeshSkeleton::MeshSkeleton(ExportableScene &scene, const ExportableNode &node,
 
         m_joints.reserve(jointCount);
 
+        // Gather the relevant input mesh data for the skinCluster
         const auto shapeDagPath = mesh.dagPath(&status);
         THROW_ON_FAILURE(status);
+        int inputShapeIndex = fnSkin.indexForOutputShape(mesh.object(), &status);
+        THROW_ON_FAILURE(status);
+
+        // Get the MPlug for input[index].inputGeometry
+        // Note: This is used over 'inputShapeAtIndex' so it includes any
+        // potential vertex tweaks after the shape but before the skinCluster
+        MPlug inputGeoPlug = fnSkin.findPlug("input", &status); // .input
+        THROW_ON_FAILURE(status);
+        inputGeoPlug = inputGeoPlug.elementByPhysicalIndex(inputShapeIndex, &status); // .input[0]
+        THROW_ON_FAILURE(status);
+        inputGeoPlug = inputGeoPlug.child(0, &status); // .input[0].inputGeometry
+        THROW_ON_FAILURE(status);
+        m_inputShape = inputGeoPlug.asMObject(&status);
+        THROW_ON_FAILURE(status);
 
         const auto bakeScaleFactor = args.getBakeScaleFactor();
         auto meshMatrix = shapeDagPath.inclusiveMatrix(&status);
@@ -60,13 +75,28 @@ MeshSkeleton::MeshSkeleton(ExportableScene &scene, const ExportableNode &node,
             auto &jointDagPath =
                 jointDagPaths[static_cast<unsigned int>(index)];
             auto *jointNode = scene.getNode(jointDagPath);
-            auto jointMatrix = jointDagPath.inclusiveMatrix(&status);
-            THROW_ON_FAILURE(status);
-            scaleTranslation(jointMatrix, bakeScaleFactor);
-
-            const auto inverseJointMatrix = jointMatrix.inverse();
 
-            MMatrix inverseBindMatrix = meshMatrix * inverseJointMatrix;
+            MMatrix inverseBindMatrix;
+            if (args.skinUsePreBindMatrixAndMesh) {
+                // Use bindPreMatrix from skinCluster
+                MPlug plug = fnSkin.findPlug("bindPreMatrix", true, &status);
+                THROW_ON_FAILURE(status);
+                size_t logical_index = fnSkin.indexForInfluenceObject(jointDagPath, &status);
+                THROW_ON_FAILURE(status);
+                plug = plug.elementByLogicalIndex(logical_index, &status);
+                THROW_ON_FAILURE(status);
+                MObject matrixData = plug.asMObject();
+                MFnMatrixData fnMatrixData(matrixData, &status);
+                THROW_ON_FAILURE(status);
+                inverseBindMatrix = fnMatrixData.matrix(&status);
+                THROW_ON_FAILURE(status);
+            } else {
+                // Use initial values time joint position
+                auto inverseJointMatrix = jointDagPath.inclusiveMatrixInverse(&status);
+                THROW_ON_FAILURE(status);
+                inverseBindMatrix = meshMatrix * inverseJointMatrix;
+            }
+            scaleTranslation(inverseBindMatrix, bakeScaleFactor);
 
             if (inverseBindMatrix.isSingular()) {
                 cerr << prefix << "WARNING: Inverse bind matrix of joint '"

diff --git a/src/MeshSkeleton.h b/src/MeshSkeleton.h
@@ -66,6 +66,10 @@ class MeshSkeleton {
 
     size_t vertexJointAssignmentSetCount() const;
 
+    MObject inputShape() const { 
+        return m_inputShape; 
+    }
+
   private:
     DISALLOW_COPY_MOVE_ASSIGN(MeshSkeleton);
 
@@ -74,6 +78,7 @@ class MeshSkeleton {
     std::vector<VertexJointAssignment> m_vertexJointAssignmentsVector;
     VertexJointAssignmentTable m_vertexJointAssignmentsTable;
     size_t m_maxVertexJointAssignmentCount;
+    MObject m_inputShape;
 
     static MObject
     tryExtractSkinCluster(const MFnMesh &fnMesh,

diff --git a/src/MeshVertices.cpp b/src/MeshVertices.cpp
@@ -168,9 +168,18 @@ MeshVertices::MeshVertices(const MeshIndices &meshIndices, const MeshSkeleton *m
 
     auto &semantics = meshIndices.semantics;
 
+    MFnMesh input_mesh;
+    if (args.skinUsePreBindMatrixAndMesh && meshSkeleton && !meshSkeleton->inputShape().isNull()) {
+       // Use skincluster input mesh data to retrieve pre-bind point positions and normals
+        input_mesh.setObject(meshSkeleton->inputShape());
+    } else {
+        // Use output mesh data at 'initialValuesTime' as bind pose point positions and normals
+        input_mesh.setObject(mesh.dagPath());
+    }
+
     // Get points
     MPointArray mPoints;
-    THROW_ON_FAILURE(mesh.getPoints(mPoints, MSpace::kTransform));
+    THROW_ON_FAILURE(input_mesh.getPoints(mPoints, MSpace::kTransform));
     const int numPoints = mPoints.length();
     m_positions.reserve(numPoints);
 
@@ -185,7 +194,7 @@ MeshVertices::MeshVertices(const MeshIndices &meshIndices, const MeshSkeleton *m
 
     const auto positionsSpan = floats(span(m_positions));
     m_table.at(Semantic::POSITION).push_back(positionsSpan);
-
+    
     // Get normals
     auto oppositePlug = mesh.findPlug("opposite", true, &status);
     THROW_ON_FAILURE(status);
@@ -198,7 +207,7 @@ MeshVertices::MeshVertices(const MeshIndices &meshIndices, const MeshSkeleton *m
     const float normalSign = shouldFlipNormals ? -1.0f : 1.0f;
 
     MFloatVectorArray mNormals;
-    THROW_ON_FAILURE(mesh.getNormals(mNormals, MSpace::kWorld));
+    THROW_ON_FAILURE(input_mesh.getNormals(mNormals, MSpace::kWorld));
     const int numNormals = mNormals.length();
     m_normals.reserve(numNormals);
     for (int i = 0; i < numNormals; ++i) {