Houdini 16.5 Nodes VOP nodes

Add VOP node

Outputs the sum of its inputs.

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This operator outputs the sum of its inputs.

The first input can be an integer, float, vector, vector4, matrix3, or matrix. The allowed data types of subsequent inputs depend on the data type of the first input. For example, if the first input is a float, subsequent inputs can be either floats or integers. The output data type is always the same as the data type for the first input.

Inputs

Input Number 1…N

The input values to be added together.

Next Input

Where the next input value should be connected. Up to 64 inputs can be specified.

Outputs

Combined Value

The sum of all the input values.

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.

FlipFluidWire Example for FLIP Solver dynamics node

This example demonstrates the use of the Flip Solver and the Fluid Force DOP. The Fluid Force DOP is used to apply a drag force on a wire object according to the motions of a flip fluid. The drag force is only applied at locations where fluid exists in the fluid object.

DiffuseSmoke Example for Gas Diffuse dynamics node

This example demonstrates how to diffuse the density of a smoke simulation using the Gas Diffuse DOP.

grass

This example simulates grass being pushed down by an RBD object. Fur Objects are used to represent the blades of grass and Wire Objects are used to simulate the motion. When a single Fur Object is used to represent the grass, neighbouring blades of grass will have similar motion. Additional objects with different stiffness values can be used to make the motion less uniform. When "Complex Mode" is enabled, two objects are used to represent the grass. The stiffness of each set of curves can be controlled by adjusting the "Angular Spring Constant" and "Linear Spring Constant" parameters on the corresponding Wire Objects.

FluidGlass Example for Particle Fluid Solver dynamics node

This example demonstrates how to get a smooth fluid stream to pour into a glass.

PopFlow Example for Particle Fluid Solver dynamics node

This example demonstrates how to integrate a POP network with a particle fluid simulation, granting one the Total Artistic Control of POPs with the fluid dynamics of the particle fluid simulator.

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.

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.

RampReference

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

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.

ColourAdvect Example for Fluid Source geometry node

This example demonstrates how you can use the Fluid Source SOP to source and advect colours from an additional volume into a smoke simulation.

repeatsmooth

This example uses the foreach sop to apply the same SOP repeatedly to the geometry, accumulating the effect of each pass.

FurBall Example for Fur geometry node

This example demonstrates how the Fur SOP builds hair-like curves based on guide curves and skin geometry.

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.

FurPipelineExample Example for Fur geometry node

This example illustrates how custom shaders can be used to define the appearance of fur generated by the Fur SOP.

FurTextureMap Example for Fur geometry node

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

Shaved Example for Fur geometry node

This example demonstrates how to use a texture to control hair density.

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.

volumeanalysis_grad Example for Volume Analysis geometry node

This example shows how to use the Volume Analysis SOP to compute the gradient of a volume and displace the geometry’s points by the gradient.

ImportVolumes Example for Volume VOP geometry node

This example shows how to import multiple volumes into a Volume VOP SOP.

pscaleVOPSOP Example for Add Attribute VOP node

I attached a file that shows various ways to create the pscale attribute. It uses three key nodes: 1) Property POP to add pscale 2) Point SOP to add pscale 3) a VOP SOP to add pscale (that is tricked out to also do random offsets)

WornMetal Example for Curvature VOP node

This example shows how the curvature vop can be added to a shader network to add a worn or distressed look to your material.

Fuzzy Logic Obstacle Avoidance Example Example for Fuzzy Defuzz VOP node

This example shows agent obstacle avoidance and path following implemented using a fuzzy logic controller.

SimpleMetaImport Example for Meta-Loop Import VOP node

This example demostrates how to use the Meta-Loop Start, Meta-Loop Next and Meta-Loop Import VOPs.

It calculates the sum of the densities of all metaballs in some input geometry, and uses that total to create an image in a Composite Network.

PointCloudIterateAverage Example for Point Cloud Iterate VOP node

This example shows how the pciterate vop can be used to average together points returned by pcopen. First, a point cloud is generated with a floating point "check" channel initialized to 1 inside a circle in the x-z plane. Then, the points are filtered in a shader by looping using the pciterate vop and averaging the value of the "check" channel. The point cloud used in the example is stored inside the asset as points.pc.

PointCloudLookup Example for Point Cloud Iterate VOP node

This example shows how to accomplish point cloud lookups for volumes using pcfilter and pciterate. It demonstrates how to iterate over and import values returned by a query.

RaytraceVopShader Example for Ray Trace VOP node

This example demonstrates a simple ray traced shader using a vop vex network. To modify the shader properties, create a properties shader in the material and connect it to the output shaders node. You can then add rendering parameters to the properties node. For example to control the number of reflection bounces, you would add the reflect limit parameter.

See also

VOP nodes