Houdini 17.5 Nodes VOP nodes

Specular VOP node

Generates a color using the selected specular lighting model calculation.

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This VOP uses the selected specular lighting model calculation to generate a color. Typically, adding this lighting model into the network, is the last thing done before connecting the resulting color to the output Cf input.

The available specular lighting models are



The normal vector is used in the selected specular calculation. The normal should be normalized if explicitly connected as an input. The face forward calculation is optional, but it is recommended. Implicitly, the normalized global variable, N, is used.


The incidence direction ray used in the selected specular calculation, as well as, the face forward calculation. The incident vector should be normalized if explicitly connected as an input. Implicitly, the normalized global variable, I, is used.


The specular intensity. It is used to darken or lighten the highlight color.


The specular highlight color. It is multiplied by the light color.


This value is used to control the size or spread of the specular highlight.


This is used only if Anisotropic specular is selected. This value controls the size or spread in the V direction of the specular highlight. If urough and vrough are the same, the highlight becomes isotropic, round rather than elliptical. Anisotropic specular is often used in metallic materials.


This value is used to control the sharpness of the edge of the specular highlight. This is used only if Glossy specular is selected. Glossy specular is used for the cornea of the eye, as well glass and other highly reflective materials.


This toggle will change the normal to face forward towards the camera. It is recommended this toggle be on.



The selected specular color highlight calculation.

Ks * spec * specularFunction(nN, -nI, urough, vrough, sharp)


Just selected specular lighting without the multiplication by the specular intensity or the specular color. Usually used as an export parameter for extra images planes used in the composite.


The PBR specular calculation.


The following examples include this node.

MotionVector Example for Mantra render node

The example demonstrates how to generate a motion vector layer for post-velocity compositing. Load the example and render 5 frames. Then in the image viewer, switch from 'C' (colour) to 'motion_vector' to see the results.


This example demonstrates the use of ramps and referenced ramps which are animated over time.

FirePit Example for Material shader node


No geometry is animated in this file. All animation is achieved by animating the textures

Flames are grids so that UV textures can easily be applied, they are then warped around a metaball using a magnet SOP. The flames are then assigned to either a yellow or blue Flames texture. The Flames' opacity mask wrap is set to Decal to prevent the texture from repeating and showing a single pixel ring at the top of the flame geometry. I'm also using a mask file named flameOpacMap.jpg to enhance the flames' shape at the top. The noise offset has been animated over $T with an greater emphasis on the Y axis so that the flames look like they are rising. This is the same reason the Noise jitter is larger for the Y axis as well.

The coals are spheres that have been copy stamped onto a deformed grid. Using Attribute Create surface nodes I am able to override and copy stamp the lava texture’s parameters at the SOP level so that local variables, such as $BBY, can be used to animate the texture. This way the texture’s crust and its crust values can be used only to form the tops of the coals. This reserves the lava aspect of the texture to be used on the bottoms of the coals. The lava intensity (Kd attribute) is then stamped and animated to create the look of embers on the bottom of coals glowing.

FurBallWorkflow Example for Fur geometry node

This example demonstrates how the Fur SOP and Mantra Fur Procedural can be applied to an animated skin geometry. CVEX shaders are used to apply a custom look to the hairs based upon attributes assigned to the geometry.

FurTextureMap Example for Fur geometry node

This example demonstrates how to use a texturemap to color fur.

See also

VOP nodes