Houdini 17.0 Nodes VOP nodes

Displace Along Normal VOP node

Displaces the surface along the surface normal by a given amount.

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This operator displaces the surface along the surface normal by a given amount. The displacement is anti-aliased.

You will often pipe the output of a pattern operator such as Stripes, Boxes, or Rings into the "amount" input. You can further control the amount of displacement by the "scale" multiplier.

Typically, this operator will be used in a displacement shader, with both outputs piped into the corresponding inputs of the Output Variables operator. Alternatively, it can be appear in a surface shader, in which case the displaced normal would be normalized and then connected to the nN input of the Lighting Model operator.

The input normal (nN) should be normalized if explicitly connected. If the position (P) and normal (nN) inputs are not connected, the global variables by the same names will be used instead.

Normals are automatically recomputed and set for output.

Note that in the SOP/POP contexts, the shears and object space deformation are not implemented. They exist as parameters for completeness only.

Tip

When doing a displacement in RenderMan, be sure to add an RSL Transform node to P before piping it into your noise VOP. Make this "current to world" and change the displace space at object level to be the camera you are rendering through. Otherwise the noise will slide.

Parameters

Displacement Amount

Overall displacement amount, including the amount for shears.

Scale

A multiplier of the amount in the perpendicular direction.

Examples

The following examples include this node.

Street Crowd Example Example for Crowd Solver dynamics node

Crowd example showing a street setup with two agent groups

The setup creates two groups of agents. The yellow agents are zombies which follow a path of the street. The blue agents are living pedestrians that wander around until they come into proximity of the zombies and then they swtich into a running state.

Triggers to change agent states are setup in the crowd_sim dopnet. The zombies group uses proximity to the stoplights and the color of the light to transition into a standing state when lights are red. The living group transition into a running state when they get close to the zombie agents.

Note

The animation clips need to be baked out before playing the scene. This should happen automatically if example is created from Crowds shelf. Otherwise save scene file to a location of your choice and click Render on '/obj/bake_cycles' ropnet to write out the files. The default path for the files is ${HIP}/agents.

FlipColumn Example for FLIP Solver dynamics node

This example demonstrates how a mixture of fluid colours can have their colour changed by a collision with a static object.

CurveForce Example for POP Curve Force dynamics node

This example demonstrates the use of the POP Curve Force node to control the flow of a particle sim AND a flip fluid sim.

StaticBalls Example for Static Object dynamics node

This example uses static object nodes in an RBD simulation of a grid falling and bouncing off three spheres before it hits the ground.

Down Hill Lava Flow Example for Material shader node

In this file we create a downhill lava flow with crust gathering and hardening at the base of the slope. All of the animation is achieved through the shader itself, and all of the geometry is completely static.

Note

Most of the parameters for the lava material are overridden by point attributes created in the surface nodes.

FirePit Example for Material shader node

Note

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.

StyleDisplacement Example for Material shader node

This is an example file showing an object made up of two quads, one with a bump map, the other with true displacement. This object is duplicated, and the second copy uses a style sheet to reverse the material assignments on the two quads.

RandomMaterial Example for Attribute String Edit geometry node

This example demonstrates how to use the Attrib String Edit SOP to modify String primitive attributes and randomize the colours on a grid on a per-primitive basis.

AlphaOmega Example for Points from Volume geometry node

This example demonstrates how to use a Points From Volume SOP to create a target goal for a flip simulation and make it fill a given piece of geometry.

UnpackWithStyle Example for Unpack geometry node

This example demonstrates the Unpack SOPs ability to evaluate style sheet information while unpacking. Nested packed primitives are used to demonstrate partial unpacking while still preserving styling information. This example also demonstrates the use of a Python SOP to extract information from the per-primitive style sheets.

See also

VOP nodes