Houdini 20.5 Nodes Geometry nodes

PolyKnit geometry node

Creates new polygons to join existing polygons.

This node type is deprecated. It is scheduled to be deleted in an upcoming revision of Houdini.

Use PolyDraw instead

(Since version 16.0.)

On this page

Warning

This node is deprecated. Please use TopoBuild or PolyFill instead.

Polygons are created by specifying a list of input points from which to “knit” the new polygons. Both triangles and quadrilaterals can be created. This tool allows you to specify a minimum number of points along which it can find the points to knit. For example, with only four points, PolyKnit can find two paths of unshared connected edges and use their points to knit polygons. Each of the paths is called a “meta” edge. The polygons that are created along these paths can either be triangles (T) or quadrilaterals (Q). The paths are computed to minimize the number of edges that are produced (and thus minimizing the number of polygons that are produced).

It is important to note that points are specified in a strip-like fashion. The points should be specified in an order such that they zig-zag along the geometry to knit. The first two points, for example, should each belong to the opposite geometries that are to be knitted together.

Using PolyKnit

  1. Click the PolyKnit tool on the Polygon tab.

  2. Click the points you want to connect.

  3. Press Enter when finished.

Tip

This tool works better when the polygons have the same number of points.

Examples

0 1 2 3 4

Builds 3 triangles (0, 1, 2), (1, 2, 3), (2, 3, 4).

0 1 2 q 3 4

Builds 1 triangle and 1 quad (0, 1, 2), (1, 2, 3, 4).

T 0 1 2

Builds triangles using point 0, and the points along the shortest path from point 1 to point 2. Points 1 and 2 must be connected.

Q 0 1 2 3

Builds quads using the points from the shortest path connecting points 0 and 3, and 1 and 2.

Parameters

Point List

Specifies the list of points which to knit. The following special characters can be used:

t

Currently building triangles

q

Currently building quadrilaterals

Q

Currently building “meta” quadrilaterals

T

Currently building “meta” triangles

Collapse Quads

Remove extra vertex from quadrilaterals that are actually triangles.

Remove Degenerate Polygons

Do not generate degenerate polygons (those collapsing to a single point or edge).

Flip Polygon Normals

Reverse order of vertices.

Unique Points

Do not reuse points from the input geometry. Only applicable if Keep Original is on.

Update Point Normals

Recomputes point normals if they exist.

Keep Original

Keep the input geometry.

Examples

PolyKnitBasic

This example demonstrates the various options for joining polygons using the PolyKnit SOP. The PolyKnit SOP is useful for filling in holes, gaps, or to re-define edges on polygonal geometry.

PolyKnit can be used to manually knit joining polygons between existing polygons. Polygons are created by specifying a list of input points from which to “knit” the new polygons.

PolyKnit will yield different results, depending on the pattern by which the points are selected or listed. Please see the Helpcard documentation for more information on how the PolyKnit SOP builds new polygons.

See also

Geometry nodes