Before you can use Feather Template, you have to go to the obj level and create a Geometry OBJ node from the tab menu.

1. After you've created the node, double-click it to dive inside.

2. There, open the tab menu again and choose Feather Template.

The tool creates three connected SOP nodes.

• The Curve SOP provides a basic shape, consisting of a shaft and two boundaries representing the vanes. The curve comes from an automatically loaded sc.bgeo file that ships with Houdini.

• A Feather Shape Organize SOP creates a name primitive attribute, and the shaft and shape groups.

• The Feather Template from Shape SOP turns the shape into feather with barbs. The node also creates a wide range of point attributes like barborient or uv_barb. Additionally, you can set a name for the feather.

Every time you call the Feather Template tool, Houdini creates the three nodes. You can then merge the individual branches through a Merge SOP and terminate the template with a Null SOP for further processing.

To shape the curves and create different feather types, you will normally use a reference image with one or more feathers - a so-called atlas.

You don’t necessarily need a reference and of course you can draw free-form feathers, but for realistic feathers, photos are the best solution. However, the steps for tracing/drawing feather are always the same.

When you trace a feather, you don’t have to consider each little detail or notch. The rough shape is enough and details are added later through appropriate nodes and

1. Select the the Curve SOP and turn on its blue Display/Render flag.

2. Move the mouse cursor over the viewport and press 2 to change the view from perspective to top.2

3. Also on the viewport press Enter to activate the drawing mode. A HUD appears in the upper left corner of the viewport with shortcuts and mouse actions.

4. The F key turns on the Edit mode. When you select a blue point on the curve it turns yellow and move you can move it around.

5. With Bezier curves you can also see green tangents with handles. When you move the handles, you can change curvature.

   You can also add new control points.

6. Again, on the viewport, press G to turn on the Draw mode.

7. Place the mouse on the curve, where you want to insert a new point, and press ⌃ Ctrl + .

8. Once you're happy with the result, press ⎋ Esc (also on the viewport) to exit the Curve tool.

By default, the barbs have more or less the same orientation, but with real feathers you can often see changes in the barbs' growth direction. Profile curves let you apply different growth directions that match the reference. To create profile curves, you need another Curve SOP.

The process of drawing and editing profile curves is the same as described above in Tracing a feather. The only difference is that the Curve SOP for the profiles is connected to the Feather Shape Organize SOP’s third input.

If the barbs turn out too angular, go to the Feather Template from Shape SOP’s Resolution section, and increase Barb Segments. There you can also use Barb Density to control the number of barbs.

The Feather Template tool’s purpose is to accelerate the process of tracing or drawing a feather’s shape. Details like clumps, frizz, dawn-like barbs, etc. are added in separate steps. There are also two fundamental ways to design a feather

• Condensed and uncondensed

The first method works with the virtual barbs you get from the Feather Template from Shape SOP. It uses specialized nodes to add clumps and noise, but possibilities can be limited. Uncondensing converts the virtual barbs into actual geometry. This method provides lets you fully customize your feathers through separate networks for the left and right vanes, VEXpressions, a wide range of attributes and other versatile nodes.