Houdini 16.5 Nodes VOP nodes

Texture VOP node

Computes a filtered sample of the texture map specified and returns an RGB or RGBA color.

This operator computes a filtered sample of the texture map specified and returns an RGB or RGBA color. If the image does not have an alpha channel (e.g. a JPEG image) and the operator returns RGBA, the alpha will be set to 1.

With no texture coordinates given, the values of the global s and t variables are used to index the texture. If both derivative inputs (ds and dt) are connected, s and t will represent the center of a square whose bottom-left and upper-right corners are (s-ds,t-dt) and (s+ds, t+dt) respectively .

To layer a texture on top of another using layered texture attributes already assigned to geometry, pipe the output of the Shading Layer Parameter into Vector To Float, then connect fval1 and fval2 to this operator’s s and t inputs, choosing the RGBA signature and Decal wrapping. Then connect the color output to a Vector4 To Vector operator to separate the RGB from the alpha. Put down a Mix operator and connect the RGB color to input2, the alpha to the bias and any previous Texture’s color to input1. Repeat this procedure as needed.

Parameters

Signature

RGB or RGBA values

Texture Map

The image file to use as a texture map.

UDIM Filename Expansion

UDIM texture filename expansion. The UDIM coordinate is computed based on the uv-coordinate: 1000 + int(u)+1 + int(v)*10. Example: "map_%(UDIM)d.rat" returns "map_1044.rat" with u=3.1, v=4.15

Source Color Space

The texture’s color space.

S Coordinate

S coordinate (or global s)

T Coordinate

T coordinate (or global t)

S Derivative

Derivative with respect to s (see UV Project)

T Derivative

Derivative with respect to t (see UV Project)

Wrap

Determines how the image is evaluated when the texture coordinates are outside the range 0-1. The options are:

Repeat

(string value repeat). The image map repeats outside the range 0 to 1. Basically, the integer component of the texture coordinate is ignored.

Streak

(string value streak). Texture coordinates are clamped to the 0 to 1 range.

Decal

(string value decal). Coordinates outside the range 0 to 1 will evaluate to the border color rather than an image color.

Filter Type

Type of anti-aliasing filter to be used for evaluation. The options are:

Box

(string value box)

Gaussian

(string value gauss)

Bartlett/Triangular

(string value bartlett)

Sinc Sharpening

(string value sinc)

Hanning

(string value hanning)

Blackman

(string value blackman)

Catmull-Rom

(string value catrom)

Mitchell

(string value mitchell)

Point Sampling

(string value point)

Filter Width

Blur the texture based on derivatives in shading contexts. For contexts that do not provide derivatives (such as the sop context), this parameter will have no effect and you should use Texture Blur or Pixel Blur instead. In shading contexts, filtering will be proportional to the micropolygon size with a filter width of 1, filtering one micropolygon.

Texture Blur

Blur the texture as a percentage of the image width. The blur is specified as 0 (no blur) to 1 (blur the entire image).

Pixel Blur

Blur the texture by the specified number of pixels. If the resolution of the map changes, the amount of blur will change.

Border Color

Border color when Decal wrapping is used.

Extrapolate Derivatives

Specifies whether derivative extrapolation should be used when computing anti-aliasing information.

Interpolate MIP Levels

Specifies whether RAT files should interpolate between different MIP levels. If enabled, it will help remove discontinuities when different MIP levels of a RAT file are accessed. However, the results of texture evaluation will be slightly softer (i.e. blurrier) and will take twice as long to compute.

Default Color

When evaluating decal textures, this is the color evaluated when outside of the decal.

Texture Channel

This specifies which color channel for multi-plane textures should be evaluated.

PTexture Face

When evaluating ptex files, the polygon face used to index into the map. This will default to the polygon number.

Texture Orientation

Sometimes texture maps (notably ptex textures) have different orientations than might be normal in Houdini. This parameter allows you to perform simple manipulations on the s and t coordinates. The operations are:

Default

Use the default s and t coordinates.

Flip S

Flip the s coordinate (horizontal flip).

Flip T

Flip the t coordinate (vertical flip).

Swap S/T

Swap the s and t coordinates (diagonal flip).

When performing any operations, the flipping occurs before the swapping.

See also

VOP nodes