VFX ANNIMATION

Introduction to houdini vfx software

WHAT IS HOUDINI

Houdini is an industry-standard 3D animation, visual effects (VFX), and procedural generation software developed by SideFX.

What Makes Houdini Unique

Procedural Node-Based Workflow: Instead of manually sculpting or editing polygons step-by-step, users build networks of interlinked rules and math (recipes). If you change an early parameter, the entire model or simulation automatically updates without losing your work.
All-in-One Powerhouse: It handles dynamic simulations (fire, smoke, water, destruction, cloth, and particles), procedural terrain generation, character rigging (KineFX), lighting, look development (Solaris/Karma), and compositing in a single environment.
Houdini Digital Assets (HDAs): Technical artists can package complex networks into custom assets with simple sliders, letting other artists generate unique geometry or effects without touching the underlying code.

HOUDINI KEY SHORTCUTS

General & Interface

Scene View & Navigation

Network View (Node Graph)

Animation & Keyframing

NODES EXPLAINED

Core Node Contexts (Networks)

Houdini organizes its nodes into different “contexts” or network levels:

Object Nodes (/obj): The top-level container for scene objects like geometry containers, lights, cameras, and character rigs.
Geometry / SOP Nodes (Surface Operators): Live inside a Geometry object to build and manipulate 3D models, curves, and points (e.g., box, transform, extrude, clip).
DOP Nodes (Dynamics Operators): Control physics simulations like fire, smoke (Pyro), cloth (Vellum), fluids, and rigid body destruction.
LOP Nodes (Lighting Operators): Build and manage scenes using USD (Universal Scene Description) for layout, lighting, and rendering.
VOP / VEX Nodes (VEX Operators): Visual node-based editors that compile down into fast VEX code to write custom shaders and attribute logic.
COP Nodes (Compositing / Copernicus): Handle real-time image and texture manipulation directly inside Houdini.
ROP Nodes (Render Operators): Set up rendering outputs and dependency pipelines for Mantra, Karma, or external renderers.
TOP Nodes (Task Operators / PDG): Automate procedural task workflows, such as batch-processing frames or distributing work across a render farm.
APEX Nodes: Used inside KineFX for modern character rigging and skeleton manipulation.

How Nodes Work Together

Inputs and Outputs: Wires connect the output port of one node to the input port of another.
Display and Render Flags: Colored flags on the side of a node dictate what you see in the 3D viewport (Display flag) or what renders out (Render flag).
Non-Destructive History: Because the entire chain is saved as a live recipe, you can jump “back in time” to tweak an early value or switch out a base shape at any point.

Our first and second week we studied new nodes and animation, example below

Workflow in Houdini for domino annimation

Build the Path: Draw a curve (such as a Bezier curve) in the viewport to define where the dominoes will travel, and use a Resample node to place points along the curve at exact intervals.
Create the Domino Geometry: Make a simple box to represent a single domino, align its base using a Match Size node, and use a Copy to Points (or Copy to Curve) node to duplicate the tile along the resampled curve.
Pack the Geometry: Add an Assemble node and turn on Create Packed Geometry so the physics solver treats each domino as an efficient rigid object.
Set Up Physics: Plug the geometry network into an RBD Bullet Solver. Add a ground plane or ground collider in the collision settings so the tiles do not fall through the floor.
Trigger the Chain Reaction: Give the first domino an initial push or velocity (using a velocity attribute or a force) so it tips over and knocks down the next tile in line.
Run the Simulation: Play the timeline to let the Bullet Solver calculate the sequential physical collisions across the row.