VEX functions

See VEX contexts to learn about the different contexts (such as surface shaders or displacement shaders) in which the various functions and statements are available.

Subtopics

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  • Du
    Takes the derivative of the given value with respect to U.
  • Dv
    Takes the derivative of the given value with respect to V.
  • Dw
    Takes the derivative of the given value with respect to the 3rd axis, for volume rendering.
  • abs
    Returns the absolute value of the argument.
  • acos
    Returns the arc-cosine of the argument.
  • addattribute
    Adds or changes a point attribute.
  • addgroup
    Adds the particle specified by point_number to the group specified.
  • addvariablename
    Adds the mapping of the attribute aname to the local variable vname.
  • alphaname
    Returns the default name of the alpha plane (as it appears in the compositor preferences).
  • ambient
    Returns the color of ambient light in the scene.
  • anoise
    These functions are similar to the Worley noise functions listed above.
  • area
    Returns the area of the micropolygon containing a variable such as P.
  • array
    Efficiently creates an array from its arguments.
  • arraylength
    Returns the length of an array.
  • ashikhmin
  • asin
    Returns the arc-sine of the argument.
  • assign
    An efficient way of extracting the components of a vector, vector4, matrix3 or matrix to float variables.
  • atan
    Returns the arc-tangent of the argument.
  • atan2
    Returns the arc-tangent of y/x.
  • atof
    Converts a string to a float.
  • atoi
    Converts a string to an integer.
  • atten
    Computes attenuated falloff.
  • avg
    Returns the average of the vector’s 3 components
  • binput
    binput returns bilinear sampled input.
  • blinn
    phong, blinn, and specular return the illumination for specular highlights using different lighting models.
  • blinnBRDF
  • bumpmap
    Bump maps will return the color gradient of the image in the du/dv parameters.
  • bumpmapA
  • bumpmapB
  • bumpmapG
  • bumpmapL
  • bumpmapR
  • bumpname
    Returns the default name of the bump plane (as it appears in the compositor preferences).
  • ceil
    Returns the smallest integer greater than or equal to the argument
  • ch
    Evaluates a channel (or parameter) and return its value.
  • chend
    Returns the end sample of the input specified.
  • chendf
    Returns the frame corresponding to the last sample of the input specified.
  • chendt
    Returns the time corresponding to the last sample of the input specified.
  • chinput
    Returns the value of a channel at the specified sample in an input.
  • chname
    Returns the channel name of the indexed plane.
  • chnumchan
    Returns the number of channels in the input specified.
  • chrate
    Returns the sample rate of the input specified.
  • chstart
    Returns the start sample of the input specified.
  • chstartf
    Returns the frame corresponding to the first sample of the input specified.
  • chstartt
    Returns the time corresponding to the first sample of the input specified.
  • cinput
    cinput returns point sampled input.
  • ckspline
    Computes a Catmull-Rom (Cardinal) spline between the key points specified.
  • clamp
    Returns value clamped between min and max.
  • clip
    clip the line segment between p0 and p1.
  • colormap
    There are various forms for looking up a color from a disk image.
  • colorname
    Returns the default name of the color plane (as it appears in the compositor preferences).
  • computenormal
    In the POP and SOP contexts, sets how/whether to recompute normals. In the shading contexts, computes normals.
  • concat
    Concatenate all the strings specified to form a single string.
  • cone
  • cos
    Returns the cosine of the argument.
  • cosh
    Returns the hyperbolic cosine of the argument.
  • cracktransform
    Depending on the value of c, returns the translate (c=0), rotate (c=1), or scale (c=2) component of the transform (xform).
  • cross
    Returns the cross product between the two vectors
  • cspline
    Computes a Catmull-Rom (Cardinal) spline between the key points specified.
  • ctransform
    Transforms between color spaces.
  • degrees
    Returns the argument from radians into degrees
  • depthmap
    The depthmap functions work on an image which was rendered as a z-depth image from mantra.
  • depthname
    Returns the default name of the depth plane (as it appears in the compositor preferences).
  • determinant
    computes the determinant of the matrix
  • diffuse
    Returns the diffuse (Lambertian) illumination given the normalized surface normal.
  • diffuseBRDF
  • dihedral
    computes the rotation matrix which rotates the vector a onto the vector b.
  • dimport
    Imports a variable from the displacement shader for the surface.
  • distance
    Returns the distance between the two 3 or 4 dimensional point arguments.
  • distance2
    Returns the squared distance between the two 3 or 4 dimensional point arguments.
  • dot
    Returns the dot product between the arguments.
  • dsmpixel
    Reads the z-records stored in a pixel of a deep shadow map or deep camera map.
  • emission_bsdf
    Returns the emissive component of a bsdf.
  • environment
    Returns the color of the environment texture.
  • eval_bsdf
    Evaluates a bsdf given two vectors and a normal.
  • eval_light
    Runs light shaders for a light and exports evaluated information.
  • exp
    Returns the exponential function of the argument.
  • fastshadow
    Sends a ray from the position P along the direction specified by the direction D.
  • filtershadow
    Sends a ray from the position P along direction D.
  • filterstep
    Returns the anti-aliased weight of the step function.
  • finput
    finput returns fully filtered pixel input.
  • fit
    Takes the value in the range (omin, omax) and shifts it to the corresponding value in the new range (nmin, nmax).
  • floor
    Returns the largest integer less than or equal to the argument
  • fntransform
  • foreach
  • forpoint
  • frac
    Returns the fractional component of the floating point number.
  • fresnel
    Computes the fresnel reflection/refraction contributions given an incoming vector, surface normal (both normalized), and an index of refraction (eta).
  • fromNDC
    Transforms a position from normal device coordinates to the coordinates in the appropriate space.
  • frontface
    If dot(I, Nref) is less than zero, N will be negated.
  • ftransform
  • fvtransform
  • gather
    Sends rays into the scene and returns information from the shaders of surfaces hit by the rays.
  • getbbox
    Sets two vectors to the minimum and maximum corners of the bounding box for the entire geometry.
  • getblurP
    Returns the blurred point position (P) vector at a fractional time between frames.
  • getbounces
  • getbounds
    Returns the bounding box of the geometry specified by the filename.
  • getcomp
    Extracts a single component of a vector type, matrix type, or array.
  • getglobalraylevel
    Returns the depth of the ray tree for computing global illumination.
  • getlightname
    Returns the name of the current light when called from within an illuminance loop, or converts an integer light ID into the light’s name.
  • getlights
    Returns an array of light identifiers for the currently shaded surface.
  • getneighbour
    Returns the point index of the neighbour of the point.
  • getneighbourcount
    Returns the number of points that are connected to the specified point.
  • getneighbours
    Returns an array of the point numbers of the neighbours of a point.
  • getobjectname
    Returns the name of the current “object” whose shader is being run.
  • getphotonlight
    Returns the integer ID of the light being used for photon shading.
  • getraylevel
    Returns the depth of the ray tree for the current shading.
  • getrayweight
    Returns an approximation to the contribution of the ray to the final pixel color.
  • getshadowscope
    Exports the shadow scope and categories for a given light.
  • gradient3d
    Returns the gradient of a single channel texture image at the position specified by P.
  • hasplane
    Returns 1 if the plane specified by the parameter exists in this COP.
  • hscript_noise
    hscript_noise, hscript_turb, hscript_snoise, and hscript_sturb mimic the Houdini expression functions noise(), snoise(), turb(), and sturb().
  • hscript_rand
    Produces the exact same results as the Houdini expression function of the same name.
  • hscript_snoise
  • hscript_sturb
  • hscript_turb
  • hsvtorgb
    Convert HSV color space into RGB color space.
  • iaspect
    Returns the aspect ratio of the specified input.
  • ichname
    Returns the channel name of the indexed plane of the given input (e.
  • ident
    computes identity matrices
  • iend
    Returns the last frame of the specified input.
  • iendtime
    Returns the end time of the specified input.
  • ihasplane
    Returns 1 if the specified input has a plane named 'planename'.
  • illuminance
    Loops through all light sources in the scene, calling the light shader for each light source to set the Cl and L global variables.
  • import
    Imports attribute data from the SOP or POP connected to the specified input.
  • importance_light
    Returns an estimate of a light’s contribution to the overall scene lighting.
  • ingroup
    Returns 1 if the particle specified by the point number is in the group specified by the string.
  • int
    if the argument is negative, this returns ceil(x), otherwise it returns floor(x).
  • integrate3d
    This function will “integrate” the 3d image along the line specified by p0 and p1.
  • integrate3dClip
    The integrate3dClip function integrates along the ray described by p0 and p1 where “interesting” things start happening in a given I3D texture.
  • interpolate
    Interpolates a value across the currently shaded micropolygon.
  • intersect
    This function computes the intersection of the specified ray with the geometry.
  • intersect3d
    This function intersects a ray (with it’s origin at p0 and extending to p1), against a 3d texture image.
  • intersect_lights
    Finds the nearest intersection of a ray with any of a list of (area) lights.
  • inumplanes
    Returns the number of planes in the given input.
  • invert
    inverts the matrix.
  • iplaneindex
    Returns the index of the plane named 'planename' in the specified input.
  • iplanename
    Returns the name of the plane specified by the planeindex of the given input (e.
  • iplanesize
    Returns the number of components in the plane named 'planename' in the specified input.
  • irate
    Returns the frame rate of the specified input.
  • irradiance
    Computes irradiance (global illumination) at the point P with the normal N.
  • isbound
    Parameters in VEX can be overridden by geometry attributes (if the attributes exist on the surface being rendered).
  • isconnected
    Returns 1 if input_number is connected, or 0 if the input is not connected.
  • isdistantlight
    Returns whether a given light is “distant” (an environment light or directional light) .
  • isfogray
    Returns 1 if the shader is being called to evaluate illumination for fog objects, or 0 if the light or shadow shader is being called to evaluate surface illumination.
  • isframes
    Returns 1 if the Vex CHOP’s Unit Menu is currently set to 'frames', 0 otherwise.
  • issamples
    Returns 1 if the Vex CHOP’s Unit Menu is currently set to 'samples', 0 otherwise.
  • isseconds
    Returns 1 if the Vex CHOP’s Unit Menu is currently set to 'seconds', 0 otherwise.
  • isshadowray
    Returns 1 if the shader is being called to evaluate opacity for shadow rays, or 0 if the shader is being called to evaluate for surface color.
  • istart
    Returns the starting frame of the specified input.
  • istarttime
    Returns the start time of the specified input.
  • ixres
    Returns the X resolution of the specified input.
  • iyres
    Returns the Y resolution of the specified input.
  • kspline
    Returns an interpolated value along a spline curve.
  • length
    Returns the length of the vector or vector4.
  • length2
    Returns the squared distance of the vector or vector4.
  • lerp
    Performs bilinear interpolation between the values.
  • limport
    Imports a variable from the light shader for the surface.
  • lkspline
    Computes a linear spline between the key points.
  • lntransform
  • log
    Returns the natural logarithm of the argument
  • log10
    Returns the logarithm (base 10) of the argument
  • lookat
    computes a rotation matrix to orient the z-axis along the vector (to-from) under the transformation.
  • lspline
    Computes a linear spline between the key points.
  • ltransform
  • luminance
    Compute the luminance of the RGB color specified by the parameters
  • lumname
    Returns the default name of the luminence plane (as it appears in the compositor preferences).
  • lvtransform
  • maketransform
    Builds a 3×3 or 4×4 transform matrix.
  • maskname
    Returns the default name of the mask plane (as it appears in the compositor preferences).
  • match
    This function returns 1 if the subject matches the pattern specified, or 0 if the subject doesn’t match.
  • matchvex_blinn
  • matchvex_specular
  • mattrib
    Returns the value of the point attribute for the metaballs if metaball geometry is specified to i3dgen.
  • max
  • mdensity
    Returns the density of the metaball field if metaball geometry is specified to i3dgen.
  • metaimport
    Once you get a handle to a metaball using metastart and metanext, you can query attributes of the metaball with metaimport.
  • metamarch
    Takes the ray defined by p0 and p1 and partitions it into zero or more sub-intervals where each interval intersects a cluster of metaballs from filename.
  • metanext
  • metastart
    Open a geometry file and return a “handle” for the metaballs of interest, at the position p.
  • metaweight
    Returns the metaweight of the geometry at position p.
  • min
  • mspace
    Transforms the position specified into the “local” space of the metaball.
  • nbouncetypes
  • newgroup
    Creates a new group in which to put particles.
  • newsampler
    Returns an initialized sampler sequence for use as the first argument to the nextsample function.
  • nextsample
  • ninput
    Reads a pixel and its eight neighbors into a 3×3 matrix.
  • noise
    There are two forms of Perlin-style noise: a non-periodic noise which changes randomly throughout N-dimensional space, and a periodic form which repeats over a given range of space.
  • normalize
    Returns the normalized vector
  • normalname
    Returns the default name of the normal plane (as it appears in the compositor preferences).
  • npoints
  • nprimitives
    Returns the number of primitives in the geometry file.
  • nrandom
    The nrandom() functions are non-deterministic random number generators for VEX.
  • ntransform
    See ptransform.
  • occlusion
    Computes ambient occlusion.
  • onoise
    These functions are similar to wnoise and vnoise.
  • ontransform
  • optransform
    Returns the transform associated with an OP.
  • otransform
    otransform, ltransform, ftransform, ontransform, lntransform, fntransform, ovtransform, lvtransform, and fvtransform query the scene for a geometry object, light or fog object of the given name.
  • ovtransform
  • ow_nspace
    Transforms a normal vector from Object to World space.
  • ow_space
    Transforms a position value from Object to World space.
  • ow_vspace
    Transforms a direction vector from Object to World space.
  • pathtrace
  • pcclose
    This function closes the handle associated with a pcopen function.
  • pcconvex
  • pcexport
    Writes data to a point cloud inside a pciterate or a pcunshaded loop.
  • pcfarthest
    Returns the distance to the farthest point found in the search performed by pcopen.
  • pcfilter
    Filters the points found by pcopen using a simple reconstruction filter.
  • pcimport
    Imports channel data from a point cloud inside a pciterate or a pcunshaded loop.
  • pciterate
    This function can be used to iterate over all the points which were found in the pcopen query.
  • pcopen
    Returns a handle to a point cloud file.
  • pcunshaded
    Iterate over all of the points of a read-write channel which haven’t had any data written to the channel yet.
  • pcwrite
    Writes data to a point cloud file.
  • phong
    phong, blinn, and specular return the illumination for specular highlights using different lighting models.
  • phongBRDF
  • phonglobe
  • photonmap
    The photonmap function will evaluate a photon map and return the resulting color information.
  • planeindex
    Returns the index of the plane specified by the parameter, starting at zero.
  • planename
    Returns the name of the plane specified by the index (e.
  • planesize
    Returns the number of components in the plane (1 for scalar planes and up to 4 for vector planes).
  • pnoise
    There are two forms of Perlin-style noise: a non-periodic noise which changes randomly throughout N-dimensional space, and a periodic form which repeats over a given range of space.
  • pointname
    Returns the default name of the point plane (as it appears in the compositor preferences).
  • pop
    Removes the last element of an array and returns it.
  • pow
    Raises the first argument to the power of the second argument
  • prim_attribute
    Evaluates the attribute string att for primitive pn at the parametric location u, v.
  • prim_normal
    Returns the normal of the primitive (prim_number) at parametric location u, v.
  • printf
    Prints values to the console which started the VEX program.
  • ptlined
    This function returns the closest distance between the point Q and a finite line segment between points P0 and P1.
  • ptransform
    Transforms a vector from one space to another.
  • push
    Adds an item to an array.
  • qconvert
    Converts a quaternion represented by a vector4 to a matrix3 representation.
  • qmultiply
    Multiplies two quaternions and returns the result.
  • quaternion
    Creates a vector4 representing a quaternion.
  • radians
    Converts the argument from degrees into radians
  • random
    generate a random number based on the position in N dimensional space (where N is 1 to 4 dimensions).
  • rawbumpmap
  • rawbumpmapA
  • rawbumpmapB
  • rawbumpmapG
  • rawbumpmapL
  • rawbumpmapR
  • rawcolormap
  • rayhittest
    Sends a ray from the position P along the direction D.
  • rayimport
    Imports a value sent by a shader in a gather loop.
  • reflect
    Returns the vector representing the reflection of the direction against the normal.
  • reflectlight
    Computes the amount of reflected light which hits the surface.
  • refract
    Returns the refraction ray given an incoming direction, the normalized normal and an index of refraction.
  • refractlight
    Computes the illumination of surfaces refracted by the current surface.
  • relbbox
    Returns the relative position of the point given with respect to the bounding box of the entire geometry.
  • removegroup
    Removes the particle specified by point_number from the group specified.
  • renderstate
    Queries the renderer for a named property.
  • resize
    Sets the length of an array.
  • rgbtohsv
    Convert RGB color space to HSV color space.
  • rint
    Rounds the number to the closest integer.
  • rotate
    applies a rotation to the given matrix.
  • sample_bsdf
    Samples a bsdf.
  • sample_light
    Returns the 3D position of a point on an area light.
  • scale
    scales the given matrix in three directions simultaneously (X, Y, Z - given by the components of the scale_vector).
  • serialize
    Flattens an array of vector or matrix types into an array of floats.
  • set
    These two functions provide a very efficient way of creating a vector/vector4.
  • setcomp
    Sets a single component of a vector type, matrix type, or array.
  • shadow
    Calls shadow shaders for the current light source.
  • shadowmap
    The shadowmap function will treat the shadow map as if the image were rendered from a light source.
  • shimport
    Imports a variable from the shadow shader for the surface.
  • shl
    Bit-shifts an integer left.
  • shr
    Bit-shifts an integer right.
  • simport
    Imports a variable sent by a surface shader in an illuminance loop.
  • sin
    Returns the sine of the argument
  • sinh
    Returns the hyperbolic sine of the argument
  • sleep
    Yields processing for a certain number of milliseconds.
  • slerp
    Quaternion blend between q1 and q2 based on the bias.
  • smooth
    Computes a number between zero and one.
  • snoise
    These functions are similar to wnoise.
  • specular
    phong, blinn, and specular return the illumination for specular highlights using different lighting models.
  • specularBRDF
    specularBRDF, phongBRDF, blinnBRDF, and diffuseBRDF return the computed BRDFs for the different lighting models used in VEX shading.
  • specularratio_bsdf
    Returns the approximate proportion of specularity in a bsdf.
  • spline
    Returns an interpolated value along a polyline or spline curve.
  • sprintf
    Formats a string like printf but returns the result as a string instead of printing it.
  • sqrt
    Returns the square root of the argument
  • storelightexports
    Stores exported data on a light.
  • strlen
    Returns the length of the string.
  • tan
    Returns the trigonometric tangent of the argument
  • tanh
    Returns the hyperbolic tangent of the argument
  • teximport
    Imports attributes from texture files.
  • texture
    Computes a filtered sample of the texture map specified.
  • texture3d
    Returns the value of the 3d image at the position specified by P.
  • texture3dBox
    This function queries the 3D texture map specified and returns the bounding box information of the file.
  • toNDC
    Transforms a position into normal device coordinates.
  • trace
    Sends a ray from P along the normalized vector D.
  • translate
    translates the given matrix
  • transpose
    transposes the given matrix
  • tw_nspace
    Transforms a normal vector from Texture to World space.
  • tw_space
    Transforms a position value from Texture to World space.
  • tw_vspace
    Transforms a direction vector from Texture to World space.
  • unserialize
    Turns a flat array of floats into an array of vectors or matrices.
  • velocityname
    Returns the default name of the velocity plane (as it appears in the compositor preferences).
  • vnoise
    Voronoi noise gives almost identical results to the Worley noise functions.
  • volume
    Returns the volume of the microvoxel containing a variable such as P.
  • volumegradient
    Calculates the volume primitive’s gradient.
  • volumesample
    Samples the volume primitive’s value.
  • vtransform
    See ptransform.
  • wireblinn
  • wirediffuse
  • wnoise
    Worley noise scatters points randomly through space (according to a nice Poisson distribution).
  • wo_nspace
    Transforms a normal vector from World to Object space.
  • wo_space
    Transforms a position value from World to Object space.
  • wo_vspace
    Transforms a direction vector from World to Object space.
  • wt_nspace
    Transforms a normal vector from World to Texture space.
  • wt_space
    Transforms a position value from World to Texture space.
  • wt_vspace
    Transforms a direction vector from World to Texture space.