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.

Functions

	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.
	albedo	Returns the albedo (percentage of reflected light) for a bsdf given the outgoing light direction.
	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	Looks 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.
	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.
	getattribute	Copies the value of a geometry attribute into a variable.
	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 within the motion blur exposure.
	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.
	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 and runs the light shader at the intersection point.
	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.
	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.
	isotropic	Returns an isotropic bsdf, which scatters light equally in all directions.
	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.
	normal_bsdf	Returns the normal for the diffuse component of a bsdf.
	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.
	pcgenerate	Generates a point cloud.
	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.
	pcopenlod	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	Copies the value of a primitive attribute at a certain parametric (u, v) position into a variable.
	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.
	resolvemissedray	Returns the background color for rays that exit the scene.
	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_geometry	Samples geometry in the scene and returns information from the shaders of surfaces that were sampled.
	sample_light	Samples a 3D position on a light source and runs the light shader at that point.
	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.
	shadow_light	Executes the shadow shader for a given light and returns the amount of shadowing as a multiplier of the shaded color.
	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.
	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.
	swizzle	Rearranges components of a vector.
	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.
	variadicarguments
	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.

VEX functions

Functions

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