See the network and parameters chapter for more information on HScript expressions. You can also use Python in parameters instead of HScript expressions.
Functions
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Returns the absolute value of the argument.
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Returns the arc-cosine of the argument.
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Returns the angular velocity required to rotate an object from one orientation to another in a certain period of time.
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Returns the arc length of a curve between two U positions.
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Returns an argument from a list of HScript-style arguments.
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Returns the number of arguments in an HScript-style list of arguments.
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Returns the arc-sine of the argument.
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Returns the arc-tangent of the argument.
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Returns the arc-tangent of y/x.
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Converts a string to a float.
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Returns bounding box information for a surface node.
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Channel segment function: Bezier interpoloation spline
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Returns the angle at the joint between two bone objects.
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Returns the smallest integer not less than the value passed in.
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Returns centroid information for a surface node.
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Returns the value of a parameter.
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Returns 1 if the specified channel exists, 0 if it doesn’t.
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Evaluates a channel with a new segment expression.
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Evaluates a channel with a new segment expression at a given frame.
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Evaluates a channel with a new segment expression at a given time.
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Evaluates a parameter at a given frame.
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return a string containing all of the channels contained in a group.
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Evaluates a channel within a CHOP at the current time.
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Evaluates a channel within a CHOP at a given time.
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Evaluates a channel within a CHOP at a specified sample point.
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Evaluates a channel within a CHOP at a specified time.
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Returns the end index of the channels in a CHOP.
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Evaluates a channel within a CHOP with at a given frame.
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Evaluates a channel within a CHOP at a given sample point.
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Returns the length of the channels in a CHOP, in samples.
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Returns the number of data channels within a CHOP.
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Returns the sample rate of a CHOP.
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Returns the start index of a CHOP.
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Returns the string value of a channel within a CHOP at the current time.
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Returns the value of a channel within a CHOP at a specified time.
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Returns the value of a ramp parameter at a specific position.
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Returns the value of a ramp parameter at a specific position and frame.
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Returns the value of a ramp parameter at a specific position and time.
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Evaluates the string value of a parameter at the current time.
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Evaluates the parameter at the current time as a node path string.
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Evaluates the parameter at the current time as a node path list string.
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Returns the raw (unexpanded) expression value of a parameter as a string.
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Returns the value of a parameter at a specified time.
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Returns a value clamped between a minimum and maximum.
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Clamps a vector to always end between a minimum and maximum sphere.
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Channel segment function: constant value.
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Tests if metadata exists on a compositing node.
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Returns numeric metadata from a compositing node.
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Returns string metadata from a compositing node.
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Returns the cosine of the argument.
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Returns the hyperbolic cosine of the argument.
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Computes the cross-product of two vectors.
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Channel segment function: cubic spline.
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Deprecated: current working container for custom panels.
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Deprecated: data type of a gadget, for custom panels.
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Deprecated: adds a menu entry on a custom panel.
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Deprecated: returns a value from a custom panel.
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Returns the curvature of the surface at the given UV coordinates.
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Deprecated: Returns the type of a gadget on a custom panel.
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Channel segment function: repeats animation from previous frames.
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Channel segment function: repeats the animation between frames f1 and f2, accumulating the value.
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Channel segment function: repeats the animation between times t1 and t2, accumulating the value.
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Channel segment function: repeats animation from previous frames.
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Converts from radians to degrees.
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Returns the degree a specified face or hull.
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Returns the value of a detail attribute.
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Returns the number of components in a detail attribute.
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Returns the type of a detail attribute.
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Returns the string value of a detail attribute.
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Returns a string from a list of strings in a detail attribute.
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Returns the number of unique stings bound to a detail attribute.
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Returns the determinant of a matrix.
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Computes the dihedral matrix between vectors v0 and v1.
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Returns the distance between two 3D points.
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Returns a space separated list of all the field names that can be passed to the dopfield function.
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Returns the full path of the node connected to a dopnetwork.
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Returns the number of records of a given type in a piece of dynamics data.
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Returns the value of a field as a float.
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Returns the name of a DOP field.
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Returns the value of a DOP field as a string.
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Returns the type of a DOP field.
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Returns the current frame of the simulation.
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Returns the simulation time equivalent of a simulation frame.
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Returns 1 if a specified DOP group contains a specified object.
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Returns 1 if a specified DOP group is mutually affecting.
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returns a string containing a list of all object groups for the current time in a specified DOP Network.
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Returns 1 if a specified DOP field exists.
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Returns 1 if a dynamics object has the specified subdata.
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Returns the list of objects processed by a DOP in the latest timestep.
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Returns the number of fields in a DOP record type.
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returns the number of objects in a simulation.
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Returns the number of records of a given type in a piece of dynamics data.
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Returns the number of types of record in a piece of dynamics data.
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Returns the number of subdata items attached to an object or data.
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Returns all objects matching the an object specification.
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Tests whether a set of objects has an affector relationship with another object.
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Returns the list of objects created by a particular DOP node.
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Returns the value of a DOP field as a float.
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Returns the value of a DOP field as a string.
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Returns the name of a record in DOPs data given its index.
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Script solver support function.
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Script solver support function.
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Script solver support function.
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Script solver support function.
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Script solver support function.
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Script solver support function.
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returns the simulation frame of a given simulation time.
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Returns the global time of a given simulation time.
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Returns the name of a subdata of a given DOP object.
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Returns the current time of a simulation.
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Returns a transformation matrix associated with a piece of data.
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Returns the simulation time equivalent to a given global time.
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Returns the velocity that a point at a location in simulation space would have if it were attached to a DOP object.
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Computes the dot product of two vectors.
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Channel segment function: ease-in and -out.
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Channel segment function: ease-in.
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Channel segment function: ease-in with configurable acceleration.
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Channel segment function: ease-out
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Channel segment function: ease-out with configurable acceleration.
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Channel segment function: ease-in and -out with configurable acceleration.
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Returns the list of edge groups in a surface node.
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Returns the list of edge groups matching a pattern in a surface node.
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Evaulates a string as an expression returning a float.
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Evaulates a string as an expression returning a string.
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Runs a string as an HScript command and returns the command’s output.
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Runs a string as an HScript command and returns the command and error output.
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Runs a string as an HScript command and returns any error output.
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Returns the logarithmic exponentiation of the argument.
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Explodes a 3×3 or 4×4 matrix into the euler rotations required to rebuild it.
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Explodes a 3×3 or 4×4 matrix into the euler rotations required to rebuild it.
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Explodes a 3×3 or 4×4 matrix into the euler rotations required to rebuild it.
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Searches the Houdini path for a file.
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Searches the Houdini path for a file or directory.
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Fits a value from one range to another.
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Fits a value to the 0-1 range.
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Fits a number in the 0-1 range.
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Fits a number to the -1 to 1 range.
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Returns the largest integer not greater than a number.
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Returns the fractional part of a floating-point number.
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Converts a number to a string.
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Returns a string describing the set of elements with a given value for an integer attribute.
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Returns a string describing the set of elements with a given value for a string attribute.
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Returns 1 if a specified detail attribute exists.
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Returns 1 if a specified point is in a specified group.
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Returns 1 if a specified point attribute exists.
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Returns 1 if a specified primitive is in a specified group.
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Returns 1 if a specified primitive attribute exists.
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Returns 1 if a specified vertex attribute exists.
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Converts a hexadecimal argument string into an integer.
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Converts RGB values to HSV components.
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Evaluates a CHOP’s input channel at a specific index.
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Returns the end index of a CHOP’s input.
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Returns the length of a CHOP’s input, in samples.
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Evaluates a CHOP’s input channel’s maximum value.
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Evaluates a CHOP’s input channel’s minimum value.
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Returns the number of channels in a CHOP’s input.
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Returns the sample rate of a CHOP’s input.
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Returns the start index of a CHOP’s input.
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Creates an identity matrix.
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Returns the value of the second or third argument depending on the truth of the first argument.
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Returns the string value of the second or third argument depending on the truth of the first argument.
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Finds the first occurrence of a pattern in a string.
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Returns the point number currently being instanced onto.
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Converts a number to an integer by truncating any fractional part.
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Converts a number into a hexadecimal string.
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Inverts a matrix.
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Queries numeric (floating point) data from an interactive render pane.
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Queries textual (string) data from an interactive render pane.
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Returns 1 if a primitive is closed.
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Returns 1 if a specified point has collided with something.
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Returns 1 if a specified Houdini environment variable exists.
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Returns 1 if a specified primitive is a NURBs or Bezier curve or surface.
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Returns 1 if a specified point is a stuck particle.
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Returns 1 if a specified Houdini or system environment variable exists.
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Returns 1 if a specified primitive is wrapped in U.
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Returns 1 if a specified primitive is wrapped in V.
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Returns the length of a vector.
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Channel segment function: linear interpolation.
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Returns a list of elements with a given value for an integer attribute.
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Returns a list of elements with a given value for a string attribute.
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Returns a value that cannot be changed.
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Returns the natural logarithm of the argument.
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Returns the base 10 logarithm of the argument.
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Channel segment function: matches the incoming and outgoing slopes.
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Channel segment function: matches the incoming slope.
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Channel segment function: matches the outgoing slope.
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Converts a string specification into a matrix.
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Converts a rotation matrix to a quaternion.
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Returns the larger of two values.
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Returns the number of columns in a matrix.
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Returns the weight of a metaball at a specific location.
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Returns the smaller of two values.
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Finds the smallest distance between a point and a primitive.
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Computes the transformation matrix of a lookat from one vector to another.
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Computes the transformation matrix of a lookat from one vector to another, with an up vector.
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Computes the transformation matrix of a lookat from one object to another.
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Blends the two modular values.
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Computes the transformation matrix to orient along specific Z and Y axes.
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Returns the full name of the pane currently under the mouse pointer.
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Returns the node path of the pane currently under the mouse pointer.
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Returns the number of rows in a matrix.
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Returns a matrix with all values set to 0.
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Finds the point in a geometry nearest to specific 3D coordinates.
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Generates 3D noise.
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Returns the components of the surface normal specific UV coordinates.
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Normalizes a vector.
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Returns the number of points in a geometry.
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Returns the number of points in the specified group.
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Returns the number of primitives in a surface node.
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Returns the number of primitives in the specified group.
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Returns the number of unique values for an integer or string attribute in a surface node.
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Returns the current global kinematic override setting for bone objects.
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Returns a list of lights matching an object’s light mask.
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Computes the rotation vector of a lookat from one object to another.
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Returns an object’s pre-transform matrix.
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Returns the value of a CHOP’s output at a specific sample index.
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Returns a pseudo-random number between 0 and 1.
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Returns the full paths of all operators in a bundle.
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Returns the creator of this node.
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Returns the numeric suffix of a node name.
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Returns 1 if the specified node, group, or bundle exists.
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Returns a list nodes with a particular flag set.
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Returns the full path of a node.
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Returns the path of a node relative to another node.
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Returns the unique ID of a node.
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Returns the name of the node connected to a given input.
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Returns the full path of the node connected to a given input.
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Returns 1 if Houdini is currently loading a scene file.
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Returns 1 if Houdini is currently shutting down.
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Returns a list of lights matching an object’s light mask.
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Sorts a list of node paths based on node input/outputs order.
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Returns the name of a node given its path.
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Returns the number of nodes inside a container node.
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Returns the maximum number of connected inputs.
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Returns the number of nodes connected to a node’s output.
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Returns the name of a node connected a given node’s output.
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Returns the full path of a node connected a given node’s output.
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Deprecated: replaced by opinput.
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Returns the path of the current network.
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Prints the path of the current network.
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Returns the relative path from one node to another.
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Returns a list of the selected nodes.
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Returns a list of the full paths of selected nodes.
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Returns a recursive list of the selected nodes.
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Returns a recursive list of the full paths of selected nodes.
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Computes the active stream of a node.
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Returns the full path of a node including any containing subnets.
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Returns the transformation matrix of an object at the current time.
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Returns the type of a node.
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Returns type information about a node.
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Returns components of an object’s transforms.
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Returns components of an object’s offset transforms.
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Returns a string padding a number to a given length with zeros.
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Deprecated: use stamp instead.
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Returns 1 if a specified parameter is a string.
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Returns the color of a pixel in a compositing node.
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Returns the non-interpolated color of a pixel in a compositing node.
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Converts an English noun to its plural.
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Returns the value of a point attribute.
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Returns the number of components in a point attribute.
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Returns the type of a point attribute.
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Returns the average of an attribute across all points in a geometry.
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Returns the distance between a point and a primitive.
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Returns the list of point groups in a surface node.
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Returns the list of point groups matching a pattern in a surface node.
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Returns a list of all points in a point group.
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Lists points that share a minimum number of primitives with a specified point.
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Returns a list of points that match a specified pattern.
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Returns the string value of a point attribute.
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Returns a string from a list of strings in a point attribute.
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Returns the number of unique strings bound to a point attribute.
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Returns the full path to a particle network context geometry.
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Returns 1 if a particle event is occurring.
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Returns the time of a particle event.
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Returns the value of a particle attribute, by particle number.
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Returns the value of a particle attribute, by particle ID.
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Returns the point number of the particle with the specified ID.
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Returns the string value of a particle attribute, by particle number.
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Returns the string value of a particle attribute, by particle ID.
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Raises a number to an exponent.
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Returns the value of a primitive attribute.
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Returns the number of components in a primitive attribute.
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Returns the type of a primitive attribute.
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Returns the minimum distance and closest points between two primitives.
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Returns the partial derivatives of a primitive attribute.
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Returns the list of primitive groups in a surface node.
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Returns the list of groups matching a pattern in a surface node.
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Returns a list of all primitives in a surface node.
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Lists primitives that share a minimum number of points with a specified primitive.
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Returns the string value of a primitive attribute.
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Returns a string from a list of strings in a primitive attribute.
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Returns the number of unique strings bound to a primitive attribute.
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Returns the value of a primitive attribute at a certain UV location.
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Prints a message to the console.
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Similar to ch(), but for render properties, with a default if the property doesn’t exist.
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Evaluates a render property at a given frame.
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Evaluates the string value of a render property at the current time.
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Evaluates a render property at the current time as a node path string.
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Evaluates the raw (unexpanded) string value of a render property at the current time.
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Evaluates a render property at a given time.
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Returns 1 when a value is within a certain range.
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Evaluates a Python expression, returning a float result.
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Evaluates a Python expression, returning a string result.
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Channel segment function: uses quaternions to interpolate.
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Converts quaternion to a 3×3 rotation matrix.
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Channel segment function: smoothly interpolates slopes and accelerations.
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Converts from degrees to radians.
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Returns a pseudo-random number from 0 to 1.
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Channel segment function.
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Converts unit UV to real UV.
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Channel segment function: repeats animation from previous frames.
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Channel segment function: repeats animation from previous frames.
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Returns the natural resolution of the image in a compositing node.
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Converts HSV values to RGB components.
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Finds the last occurrence of a pattern in a string.
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Rounds to the nearest integer.
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Returns a 4×4 rotation matrix from an axis and angle.
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Returns a 4×4 rotation matrix from an angle and a vector.
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Rounds a number to the nearest integer.
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Runs a string as an HScript command and returns the command’s output.
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Runs a string as an HScript command and returns the command and error output.
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Runs a string as an HScript command and returns any error output.
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Takes three scaling values and returns a scale matrix.
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Lists all seam points in a surface node.
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Returns 1 if a specified compositing node has an animated sequence.
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Returns the end frame of a compositing node’s image sequence.
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Returns the number of frames in a compositing node’s image sequence.
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Returns the start frame of a compositing node’s image sequence.
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Returns the shader string generated by a shader.
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Returns -1, 0, or 1 depending on the sign of the argument.
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Returns the sine of the argument.
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Returns the hyperbolic sine of the argument.
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Takes a value and range and returns a smooth interpolation between 0 and 1.
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Generates sparse convolution 3D noise.
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Returns a knot value on a spline curve or surface.
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Channel segment function: fits a curve to the keyframes.
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Returns the square root of the argument.
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Returns a copy stamping floating point value.
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Returns a copy stamping string value.
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Returns a global state variable floating point value.
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Returns a global state variable floating point value.
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Compares two strings, ignoring case.
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Returns 1 if a string matches a pattern, ignoring case.
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Returns the concatenation of two strings.
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Compares two strings.
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Duplicates a string.
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Strips non-essential characters from the string representation of a matrix or vector.
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Returns the number of characters in a string.
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Returns 1 if a string matches a pattern, including case.
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Replaces substrings with a new string.
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Generates spatially coherent 3D noise based on sparse convolution.
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Returns a substring of a string.
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Returns the length of the 3D curve between two points on a surface.
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Runs a system command line and returns the output.
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Runs a system command line and returns the exit status.
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Runs a system command line and returns the output with no processing.
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Returns the tangent of the argument.
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Returns the hyperbolic tangent of the argument.
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Returns the interpolated color of a point on an on-disk texture map.
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Returns the non-interpolated color of a point on an on-disk texture map.
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Returns the all-lowercase version of a string.
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Returns the all-uppercase version of a string.
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Takes X, Y, and Z translation values and returns a translation matrix.
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Transposes a matrix.
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Converts a number to an integer by truncating any fractional part, rounding towards 0.
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Generates spatially coherent 3D noise.
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Returns a unique value of an integer attribute.
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Returns a unique value of a string attribute.
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Converts real UV to unit UV.
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Returns the distance between parameteric locations on two primitives.
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Returns the angle between two vectors.
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Converts a string specification into a vector.
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Converts three values into a 3-component vector.
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Converts four values into a 4-component vector.
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Returns the value of a vertex attribute.
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Returns the number of components in a vertex attribute.
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Returns the type of a vertex attribute.
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Returns the string value of a vertex attribute.
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Returns a string from a list of strings in a vertex attribute.
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Returns the number of unique strings bound to a point attribute.
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Returns the length of a vector.
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Channel segment function: matches the incoming and outgoing slopes.
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Channel segment function: matches the incoming slope.
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Channel segment function: matches the outgoing slope.
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Returns the average value of all the voxels in a volume.
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Returns the gradient of a volume primitive at a specified location.
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Returns the value of a volume primitive at a specified voxel.
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Converts volume voxel coordinates to world-space coordinates.
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Returns the maximum value of all voxels in a volume.
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Returns the minimum value of all voxels in a volume.
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Converts world space coordinates to volume voxel coordinates.
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Returns the resolution of a volume.
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Returns the value of a volume at a specified position.
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Returns the approximage diameter of a volume voxel in world space.
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Returns a vector of an objects' transforms.
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Takes a viewer name and a viewport number and returns the viewport’s name.
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Returns a vector of an object’s rotations.
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Multiplies a vector by a scaling factor.
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Creates a vector with each component set to the same value.
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Returns the number of elements in a vector.
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Returns a vector of an object’s translations.
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Wraps a value between a minimum and maximum.
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Returns the distance between a 3D coordinate and a primitive.
