The HDA or Houdini Digital Asset is a real-time configurable model asset created in a game engine such as Unity 3D.

There are simple implementations that are needed to create and asset for Unity using Houdini.

Overview

Below are very high level areas that are covered when making a simple Houdini HDA.

Geometry

Points and Mesh com alive at this stage of the graph. Knowing where to start can be the hardest thing, although a box is always nice.

Place initial primitive flat on ground(base) for easy layout.

The Edge Divide node is good for loop slicing primitive meshes.

UV

For simple game props, you will usually flatten the main mesh before moving on down the graph.

Use the Flattening Constraints to add edge cuts for good UV flattening.

Bevel/Displace

Add any beveling, displacement, masking etc to bring variation into the game asset.

Create a Group node and select the bevel edges using the Include by Edges and set the Min Edge Angle to capture only the edges within the tolerance.

Create an Attribute Randomize node to randomize the point scale(@pscale) of each point. When the bevel is applied, it can use this random value to offset the bevel of each point, causing nice variation in an uneven surface for normal baking etc or the actual geometry.

Create Taper nodes to stylize the variation even more.

UV Layout

Let the UV Layout node do the work.

Normal

Add normals to the vertices with a Normal node (adds the @N attribute to all vertices).

Color/Texture

Add a Color or Material node for game asset textures.

Export

Save node type and off to the races.