Houdini Variable

$TX, TY, TZ : Point position.

$TW : See WEIGHT.

$CEX, CEY, CEZ : The centroid of the geometry.

$XMIN, XMAX : The X extents of the bounding box of the geometry.

$YMIN, YMAX : The Y extents of the bounding box of the geometry.

$ZMIN, ZMAX : The Z extents of the bounding box of the geometry

$SIZEX, SIZEY, SIZEZ : The size of the bounding box.

$BBX, BBY, BBZ : The point’s relative position in the bounding box.

$WEIGHT : Point spline weight.

$PT : The point number of the currently processed point.

$PR, NPR : Primitive number & total number of primitives.

$VTX, NVTX : Vertex number & total number of vertices.

$NPT : The total number of points in the template geometry.

$LIFE : Percent of total life used (from 0 to 1).

$NX, NY, NZ : Normal vector.

$MAPU, MAPV, MAPW : Point or vertex texture coordinates.

$VX, VY, VZ : Velocity direction.

$MAT : Material name specification.

$CR, CG, CB : Diffuse point or vertex color.

$CA : Point or vertex alpha value.

$COMX, COMY, COMZ : Center of mass.

$LOD : Level of detail.

$RESTX, RESTY, RESTZ : The rest position.

$DIST : Distance from particle to last collision.

$MASS : Point mass.

$DRAG : Point drag.

$TENSION : Spring tension of an edge.

$SPRINGK : Elasticity of a point.

$PSCALE : Particle Scale.

$AGE : The seconds a particle in the template has been alive.

$CREASE : Point or vertex crease weight value.

$AREA : The surface area of the primitive (created by the Measure SOP).

$PERIMETER : The perimeter of the primitive (created by the Measure SOP).

$ID : The ID of the particle in the input.

$UPX, UPY, UPZ : The vector pointed in the up direction.

$WIDTH : The width of the curve. Used by mantra for rendering curves & polywire for generating trees.

$SEGS : Number of segments to divide a curve up into in Polywire (created by L-systems).

$DIV : Number of divisions to build the circle swept with Polywire (created by L-systems).

$LAGE : The age of the point in the L-system computation.

$ARC : Arc length distance from root in the L-systems.

$GEN : Generation in the L-systems.

$CURLAYER : Stores the currently processed layer for texture/materials (set by the Layer SOP).

$MAXLAYER : The number of layers that are considered active for display.