user: Describe F from the Blender manual or Python API, including usage steps and snippets.

assistant: tions)](freestyle.functions.html#freestyle.functions.freestyle.functions.GetZF1D) - [freestyle.functions.IncrementChainingTimeStampF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.IncrementChainingTimeStampF1D) - [freestyle.functions.LocalAverageDepthF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.LocalAverageDepthF0D) - [freestyle.functions.LocalAverageDepthF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.LocalAverageDepthF1D) - [freestyle.functions.MaterialF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.MaterialF0D) - [freestyle.functions.Normal2DF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.Normal2DF0D) - [freestyle.functions.Normal2DF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.Normal2DF1D) - [freestyle.functions.Orientation2DF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.Orientation2DF1D) - [freestyle.functions.Orientation3DF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.Orientation3DF1D) - [freestyle.functions.pyCurvilinearLengthF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyCurvilinearLengthF0D) - [freestyle.functions.pyDensityAnisotropyF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyDensityAnisotropyF0D) - [freestyle.functions.pyDensityAnisotropyF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyDensityAnisotropyF1D) - [freestyle.functions.pyGetInverseProjectedZF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyGetInverseProjectedZF1D) - [freestyle.functions.pyGetSquareInverseProjectedZF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyGetSquareInverseProjectedZF1D) - [freestyle.functions.pyInverseCurvature2DAngleF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyInverseCurvature2DAngleF0D) - [freestyle.functions.pyViewMapGradientNormF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyViewMapGradientNormF0D) - [freestyle.functions.pyViewMapGradientNormF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyViewMapGradientNormF1D) - [freestyle.functions.pyViewMapGradientVectorF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.pyViewMapGradientVectorF0D) - [freestyle.functions.QuantitativeInvisibilityF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.QuantitativeInvisibilityF0D) - [freestyle.functions.QuantitativeInvisibilityF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.QuantitativeInvisibilityF1D) - [freestyle.functions.ReadCompleteViewMapPixelF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.ReadCompleteViewMapPixelF0D) - [freestyle.functions.ReadMapPixelF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.ReadMapPixelF0D) - [freestyle.functions.ReadSteerableViewMapPixelF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.ReadSteerableViewMapPixelF0D) - [freestyle.functions.ShapeIdF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.ShapeIdF0D) - [freestyle.functions.TimeStampF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.TimeStampF1D) - [freestyle.functions.VertexOrientation2DF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.VertexOrientation2DF0D) - [freestyle.functions.VertexOrientation3DF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.VertexOrientation3DF0D) - [freestyle.functions.ZDiscontinuityF0D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.ZDiscontinuityF0D) - [freestyle.functions.ZDiscontinuityF1D (class in freestyle.functions)](freestyle.functions.html#freestyle.functions.freestyle.functions.ZDiscontinuityF1D) - freestyle.predicates   - [module](freestyle.predicates.html#module-freestyle.predicates) - [freestyle.predicates.AndBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.AndBP1D) - [freestyle.predicates.AndUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.AndUP1D) - [freestyle.predicates.ContourUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.ContourUP1D) - [freestyle.predicates.DensityLowerThanUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.DensityLowerThanUP1D) - [freestyle.predicates.EqualToChainingTimeStampUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.EqualToChainingTimeStampUP1D) - [freestyle.predicates.EqualToTimeStampUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.EqualToTimeStampUP1D) - [freestyle.predicates.ExternalContourUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.ExternalContourUP1D) - [freestyle.predicates.FalseBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.FalseBP1D) - [freestyle.predicates.FalseUP0D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.FalseUP0D) - [freestyle.predicates.FalseUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.FalseUP1D) - [freestyle.predicates.Length2DBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.Length2DBP1D) - [freestyle.predicates.MaterialBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.MaterialBP1D) - [freestyle.predicates.NotBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.NotBP1D) - [freestyle.predicates.NotUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.NotUP1D) - [freestyle.predicates.ObjectNamesUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.ObjectNamesUP1D) - [freestyle.predicates.OrBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.OrBP1D) - [freestyle.predicates.OrUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.OrUP1D) - [freestyle.predicates.pyBackTVertexUP0D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyBackTVertexUP0D) - [freestyle.predicates.pyClosedCurveUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyClosedCurveUP1D) - [freestyle.predicates.pyDensityFunctorUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyDensityFunctorUP1D) - [freestyle.predicates.pyDensityUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyDensityUP1D) - [freestyle.predicates.pyDensityVariableSigmaUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyDensityVariableSigmaUP1D) - [freestyle.predicates.pyHighDensityAnisotropyUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHighDensityAnisotropyUP1D) - [freestyle.predicates.pyHighDirectionalViewMapDensityUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHighDirectionalViewMapDensityUP1D) - [freestyle.predicates.pyHigherCurvature2DAngleUP0D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHigherCurvature2DAngleUP0D) - [freestyle.predicates.pyHigherLengthUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHigherLengthUP1D) - [freestyle.predicates.pyHigherNumberOfTurnsUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHigherNumberOfTurnsUP1D) - [freestyle.predicates.pyHighSteerableViewMapDensityUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHighSteerableViewMapDensityUP1D) - [freestyle.predicates.pyHighViewMapDensityUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHighViewMapDensityUP1D) - [freestyle.predicates.pyHighViewMapGradientNormUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyHighViewMapGradientNormUP1D) - [freestyle.predicates.pyIsInOccludersListUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyIsInOccludersListUP1D) - [freestyle.predicates.pyIsOccludedByIdListUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyIsOccludedByIdListUP1D) - [freestyle.predicates.pyIsOccludedByItselfUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyIsOccludedByItselfUP1D) - [freestyle.predicates.pyIsOccludedByUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyIsOccludedByUP1D) - [freestyle.predicates.pyLengthBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyLengthBP1D) - [freestyle.predicates.pyLowDirectionalViewMapDensityUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyLowDirectionalViewMapDensityUP1D) - [freestyle.predicates.pyLowSteerableViewMapDensityUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyLowSteerableViewMapDensityUP1D) - [freestyle.predicates.pyNatureBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyNatureBP1D) - [freestyle.predicates.pyNatureUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyNatureUP1D) - [freestyle.predicates.pyNFirstUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyNFirstUP1D) - [freestyle.predicates.pyParameterUP0D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyParameterUP0D) - [freestyle.predicates.pyParameterUP0DGoodOne (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyParameterUP0DGoodOne) - [freestyle.predicates.pyProjectedXBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyProjectedXBP1D) - [freestyle.predicates.pyProjectedYBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyProjectedYBP1D) - [freestyle.predicates.pyShapeIdListUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyShapeIdListUP1D) - [freestyle.predicates.pyShapeIdUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyShapeIdUP1D) - [freestyle.predicates.pyShuffleBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyShuffleBP1D) - [freestyle.predicates.pySilhouetteFirstBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pySilhouetteFirstBP1D) - [freestyle.predicates.pyUEqualsUP0D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyUEqualsUP0D) - [freestyle.predicates.pyVertexNatureUP0D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyVertexNatureUP0D) - [freestyle.predicates.pyViewMapGradientNormBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyViewMapGradientNormBP1D) - [freestyle.predicates.pyZBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyZBP1D) - [freestyle.predicates.pyZDiscontinuityBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyZDiscontinuityBP1D) - [freestyle.predicates.pyZSmallerUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.pyZSmallerUP1D) - [freestyle.predicates.QuantitativeInvisibilityRangeUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.QuantitativeInvisibilityRangeUP1D) - [freestyle.predicates.QuantitativeInvisibilityUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.QuantitativeInvisibilityUP1D) - [freestyle.predicates.SameShapeIdBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.SameShapeIdBP1D) - [freestyle.predicates.ShapeUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.ShapeUP1D) - [freestyle.predicates.TrueBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.TrueBP1D) - [freestyle.predicates.TrueUP0D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.TrueUP0D) - [freestyle.predicates.TrueUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.TrueUP1D) - [freestyle.predicates.ViewMapGradientNormBP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.ViewMapGradientNormBP1D) - [freestyle.predicates.WithinImageBoundaryUP1D (class in freestyle.predicates)](freestyle.predicates.html#freestyle.predicates.freestyle.predicates.WithinImageBoundaryUP1D) - freestyle.shaders   - [module](freestyle.shaders.html#module-freestyle.shaders) - [freestyle.shaders.BackboneStretcherShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.BackboneStretcherShader) - [freestyle.shaders.BezierCurveShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.BezierCurveShader) - [freestyle.shaders.BlenderTextureShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.BlenderTextureShader) - [freestyle.shaders.CalligraphicShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.CalligraphicShader) - [freestyle.shaders.ColorNoiseShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.ColorNoiseShader) - [freestyle.shaders.ConstantColorShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.ConstantColorShader) - [freestyle.shaders.ConstantThicknessShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.ConstantThicknessShader) - [freestyle.shaders.ConstrainedIncreasingThicknessShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.ConstrainedIncreasingThicknessShader) - [freestyle.shaders.GuidingLinesShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.GuidingLinesShader) - [freestyle.shaders.IncreasingColorShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.IncreasingColorShader) - [freestyle.shaders.IncreasingThicknessShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.IncreasingThicknessShader) - [freestyle.shaders.PolygonalizationShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.PolygonalizationShader) - [freestyle.shaders.py2DCurvatureColorShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.py2DCurvatureColorShader) - [freestyle.shaders.pyBackboneStretcherNoCuspShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.pyBackboneStretcherNoCuspShader) - [freestyle.shaders.pyBackboneStretcherShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.pyBackboneStretcherShader) - [freestyle.shaders.pyBluePrintCirclesShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.pyBluePrintCirclesShader) - [freestyle.shaders.pyBluePrintDirectedSquaresShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.pyBluePrintDirectedSquaresShader) - [freestyle.shaders.pyBluePrintEllipsesShader (class in freestyle.shaders)](freestyle.shaders.html#freestyle.shaders.freestyle.shaders.pyBluePrintEllipsesS