Gaussian Splats Writing

Changes

@@ -1,7 +1,12 @@
 10.7.x.x (relative to 10.7.3.1)
 ========
 
+Improvements
+------------
 
+- USD :
+  - All `radiance:sphericalHarmonicsCoefficients` are now loaded for `ParticleField3DGaussianSplat` objects, regardless of the `radiance:sphericalHarmonicsDegree`.
+  - Added write support for `ParticleField3DGaussianSplat`.
 
 10.7.3.1 (relative to 10.7.3.0)
 ========

contrib/IECoreUSD/src/IECoreUSD/GaussianSplatAlgo.cpp

@@ -113,33 +113,53 @@ IECore::ObjectPtr readGaussianSplat( pxr::UsdVolParticleField3DGaussianSplat &sp
 
 	Canceller::check( canceller );
 	pxr::UsdAttribute degreeAttr = splats.GetRadianceSphericalHarmonicsDegreeAttr();
-	auto degreeData = boost::static_pointer_cast<IntData>( DataAlgo::fromUSD( degreeAttr, time, false ) );
-	newPoints->variables["radiance:sphericalHarmonicsDegree"] = PrimitiveVariable( PrimitiveVariable::Interpolation::Constant, degreeData );
-
-	const int degree = degreeData->readable();
-	const int coefficientCount = ( degree + 1 ) * ( degree + 1 );
+	PrimitiveAlgo::readPrimitiveVariable( degreeAttr, time, newPoints.get(), "radiance:sphericalHarmonicsDegree", PrimitiveVariable::Interpolation::Constant );
 
 	pxr::UsdAttribute coefficientsAttr;
 	splats.UsesFloatRadianceCoefficients( &coefficientsAttr );
-	auto allCoefficientsData = runTimeCast<V3fVectorData>( DataAlgo::fromUSD( coefficientsAttr, time ) );
 
-	if( allCoefficientsData && allCoefficientsData->readable().size() >= coefficientCount * newPoints->getNumPoints() )
+	if( auto allCoefficientsData = runTimeCast<V3fVectorData>( DataAlgo::fromUSD( coefficientsAttr, time ) ) )
 	{
 		const std::vector<Imath::V3f> &allCoefficients = allCoefficientsData->readable();
 
-		for( int i = 0; i < coefficientCount; ++i )
+		if( allCoefficients.size() % newPoints->getNumPoints() == 0 )
 		{
-			Canceller::check( canceller );
-
-			V3fVectorDataPtr coefficientsData = new V3fVectorData();
-			std::vector<Imath::V3f> &coefficients = coefficientsData->writable();
-			coefficients.resize( newPoints->getNumPoints() );
-			for( size_t j = 0, eJ = newPoints->getNumPoints(); j < eJ; ++j )
+			const int coefficientsCount = allCoefficients.size() / newPoints->getNumPoints();
+			int degree;
+			degreeAttr.Get( &degree, time );
+			if( coefficientsCount != ( degree + 1 ) * ( degree + 1 ) )
 			{
-				coefficients[j] = allCoefficients[j * coefficientCount + i];
+				IECore::msg(
+					IECore::Msg::Warning,
+					"GaussianSplatAlgo::readGaussianSplat",
+					"Attribute \"radiance:sphericalHarmonicsCoefficients\" size does not match that expected by \"radiance:sphericalHarmonicsDegree\" at location \"{}\".",
+					splats.GetPrim().GetPath().GetAsString()
+				);
 			}
 
-			newPoints->variables[fmt::format( "radiance:sphericalHarmonicsCoefficients:{}", i )] = PrimitiveVariable( PrimitiveVariable::Interpolation::Vertex, coefficientsData );
+			for( int i = 0; i < coefficientsCount; ++i )
+			{
+				Canceller::check( canceller );
+
+				V3fVectorDataPtr coefficientsData = new V3fVectorData();
+				std::vector<Imath::V3f> &coefficients = coefficientsData->writable();
+				coefficients.resize( newPoints->getNumPoints() );
+				for( size_t j = 0, eJ = newPoints->getNumPoints(); j < eJ; ++j )
+				{
+					coefficients[j] = allCoefficients[j * coefficientsCount + i];
+				}
+
+				newPoints->variables[fmt::format( "radiance:sphericalHarmonicsCoefficients:{}", i )] = PrimitiveVariable( PrimitiveVariable::Interpolation::Vertex, coefficientsData );
+			}
+		}
+		else
+		{
+			IECore::msg(
+				IECore::Msg::Warning,
+				"GaussianSplatAlgo::readGaussianSplat",
+				"Attribute \"radiance:sphericalHarmonicsCoefficients\" has invalid length at location \"{}\".",
+				splats.GetPrim().GetPath().GetAsString()
+			);
 		}
 	}
 

contrib/IECoreUSD/src/IECoreUSD/PointsAlgo.cpp

@@ -40,8 +40,13 @@
 
 #include "IECore/SimpleTypedData.h"
 
+#include "boost/algorithm/string/predicate.hpp"
+
 IECORE_PUSH_DEFAULT_VISIBILITY
 #include "pxr/usd/usdGeom/points.h"
+#if PXR_VERSION >= 2603
+#include "pxr/usd/usdVol/particleField3DGaussianSplat.h"
+#endif
 IECORE_POP_DEFAULT_VISIBILITY
 
 using namespace IECore;
@@ -94,6 +99,104 @@ namespace
 
 bool writePoints( const IECoreScene::PointsPrimitive *points, const pxr::UsdStagePtr &stage, const pxr::SdfPath &path, pxr::UsdTimeCode time )
 {
+#if PXR_VERSION >= 2603
+	auto type = points->variableData<const StringData>( "type", PrimitiveVariable::Constant );
+	if( type && type->readable() == "gaussianSplat" )
+	{
+		auto usdSplats = pxr::UsdVolParticleField3DGaussianSplat::Define( stage, path );
+
+		int maxCoefficientsIndex = -1;
+		std::unordered_map<int, const V3fVectorData *> coefficientsMap;
+
+		for( const auto &p : points->variables )
+		{
+			if( p.first == "P" )
+			{
+				usdSplats.CreatePositionsAttr().Set( PrimitiveAlgo::toUSDExpanded( p.second ), time );
+			}
+			else if( p.first == "orientations" )
+			{
+				usdSplats.CreateOrientationsAttr().Set( PrimitiveAlgo::toUSDExpanded( p.second ), time );
+			}
+			else if( p.first == "scales" )
+			{
+				usdSplats.CreateScalesAttr().Set( PrimitiveAlgo::toUSDExpanded( p.second ), time );
+			}
+			else if( p.first == "opacities" )
+			{
+				usdSplats.CreateOpacitiesAttr().Set( PrimitiveAlgo::toUSDExpanded( p.second ), time );
+			}
+			else if( p.first == "radiance:sphericalHarmonicsDegree" )
+			{
+				usdSplats.CreateRadianceSphericalHarmonicsDegreeAttr().Set( DataAlgo::toUSD( p.second.data.get() ), time );
+			}
+			else if( p.first == "projectionModeHint" )
+			{
+				usdSplats.CreateProjectionModeHintAttr().Set( DataAlgo::toUSD( p.second.data.get() ), time );
+			}
+			else if( p.first == "sortingModeHint" )
+			{
+				usdSplats.CreateSortingModeHintAttr().Set( DataAlgo::toUSD( p.second.data.get() ), time );
+			}
+			else if( boost::starts_with( p.first, "radiance:sphericalHarmonicsCoefficients:" ) )
+			{
+				try
+				{
+					const int coefficientsIndex = std::stoi( p.first.substr( 40 ) );  // 40 = length of `radiance:...` prefix
+
+					if( p.second.data->typeId() != V3fVectorDataTypeId || p.second.interpolation != PrimitiveVariable::Interpolation::Vertex )
+					{
+						IECore::msg(
+							IECore::Msg::Warning,
+							"PointsAlgo::writePoints",
+							"Invalid primitive variable \"{}\" on location \"{}\". Spherical harmonics coefficients must be of type V3fVectorData with Vertex interpolation.",
+							p.first, path.GetAsString()
+						);
+						continue;
+					}
+
+					coefficientsMap[coefficientsIndex] = static_cast<const V3fVectorData *>( p.second.data.get() );
+					maxCoefficientsIndex = std::max( maxCoefficientsIndex, coefficientsIndex );
+				}
+				catch( ... )
+				{
+					PrimitiveAlgo::writePrimitiveVariable( p.first, p.second, usdSplats, time );
+				}
+			}
+			else if(  p.first == "type" )
+			{
+				// This is intrinsic to `UsdVolParticleField3DGaussianSplat`
+				continue;
+			}
+			else
+			{
+				PrimitiveAlgo::writePrimitiveVariable( p.first, p.second, usdSplats, time );
+			}
+		}
+
+		if( !coefficientsMap.empty() )
+		{
+			const int coefficientsCount = maxCoefficientsIndex + 1;
+			pxr::VtArray<pxr::GfVec3f> allCoefficients( coefficientsCount * points->getNumPoints() );
+
+			for( const auto &[i, coefficientsData] : coefficientsMap )
+			{
+				const std::vector<Imath::V3f> &coefficients = coefficientsData->readable();
+
+				for( size_t j = 0, eJ = points->getNumPoints(); j < eJ; ++j )
+				{
+					allCoefficients[j * coefficientsCount + i] = DataAlgo::toUSD( coefficients[j] );
+				}
+			}
+
+			usdSplats.CreateRadianceSphericalHarmonicsCoefficientsAttr().Set( allCoefficients, time );
+		}
+
+		return true;
+	}
+
+#endif
+
 	auto usdPoints = pxr::UsdGeomPoints::Define( stage, path );
 	for( const auto &p : points->variables )
 	{