Heavily Nested MarkupExtensions

<GeometryModel3D Material="{uzi:VisualEffectMaterial Key=Arm, VisualEffect={uzi:SenseEffectExtension}}"
                 Geometry="{uzi:CylinderMesh CacheKey=1,
                 P1={uzi:Point3DVal Z={uzi:DoubleSum A={uzi:DoubleProduct A={uzi:DoubleVal Key=Length,Value=0.75, MinValue=0.1, MaxValue=1.5}, B=-1}, B=-0.09}},
                 P2={uzi:Point3DVal Z=0.16},
                 Diameter={uzi:DoubleVal Key=Diameter,Value=0.4, MinValue=0.05, MaxValue=1.0},
                 ThetaDiv={uzi:IntVal Key=Theta,Value=16, MinValue=8, MaxValue=20},
                 BaseCap=true,TopCap=true}"> 
</GeometryModel3D>

This is a bit of the part for an Arm model fragment. I use a lot of markup extensions to get the GeometryModel3D to be flexible enough for composition and environment shading.

First, the Material is a VisualEffectMaterial, which uses the Key to work with the Meta-Model system to figure out which texture to apply. The VisualEffect is mapped to the standard SenseEffectExtension, so that creature senses can be applied at render time.

The next big piece is the CylinderMesh used to provide the Geometry. This uses the HelixToolkit’s MeshBuilder to define parameters for creating a cylinder mesh. The Point3DVals are extensions to defined points (obviously), and the DoubleVals and IntVals define parameters that can be overriden when composing in a MetaModel. Lastly, the DoubleProduct (there’s also a DoubleSum) define mathematical functions on DoubleVals so that a same parameter can be re-used in multiple places as a factor (or sum) of other values.