Houdini 13.0 Nodes

interface version 1

An alternative version of the original Ray SOP (with some extra features).

  • Ray and Stick: on the left, points are rayed on a torus, and intersection attributes are stored; on the right, the points are sticked on the deformed geometry (based on the intersection attribs).

There are both advantages and disadvantages, compared to the original Ray SOP.

Advantages

  • Much faster, especially on large data sets and multi-threaded (the main reason for this OPs existence).

  • Can create both ray hit and ray miss point groups

  • “Stick” mode: once points are rayed to a geometry, they can be sticked onto a deforming version of the geometry, using the generated primitive index and U/V attributes

Limitations

  • Can only work in Project Rays mode (no Minimum Distance mode)

  • No multiple ray samples (although that’s very useful for geometry with holes)

Tip

The poly soup geometry type can be used as a collider and it’s much faster to triangulate than regular polygons (can be 10-15 times faster).

Parameters

Triangulate Collider

Triangulate the collision (2nd) geometry.

Non-planar polygons as ray colliders might give inaccurate results (usually resulting in “spikes” appering in the projected geometry). If this happens, try enabling this option.

This option can be slow for large geometry (see Optimize below).

Optimize (Pre-Triangulate)

This option “optimizes” the collision geometry before triangulation (currently it converts it to a poly soup, as it is very fast to triangulate).

Note

When building a Ray/Stick workflow, do not enable Triangulate or Optimize (they change the topology), and don’t use the poly soup type as collider.

Ray

Regular ray mode – projection of points onto a collision geometry.

For most parameter descriptions see the original Ray SOP documentation.

Ray Attribute

Create a vector attribute that points from the intersection points back to their original positions.

Flip

Reverse the direction of the Ray Attribute vectors.

Distance Attribute

Store individual ray distances in a float attribute.

Ray Hit Group

Add points to this group that hit the target surface.

Ray Miss Group

Add points to this group that missed the target surface.

Import Attributes from Hits

If enabled, the specified per-point attributes will be retrieved from the hit points of the collision geometry.

Keep Intersection Attribs

If enabled, all intersection information (intersected primitive number, U/V coordinates) will be preserved.

Note

The intersection U/V attributes are per-primitive barycentric coordinates (and not regular UV texture coordinates).

Prim, U, V Attribs

Names of the extra intersection attributes.

Debug (Show Code)

Temporary, debugging-related parameter (will be removed).

Stick

This mode sticks points (from the first input) to the surface of the geometry connected to the second input.

Sticking requires per-point attributes for primitive index and U/V coordinates on each point of the 1st geometry. (These attributes can be generated with a Ray qL SOP in regular Ray mode.)

Stick works only with regular polygons (i.e. no poly soups).

Envelope, Weighting, etc.

The standard issue deformer-weighting parameters.

Prim Num, U, V Attrib

Names of the per-point intersection attributes for sticking each point to the surface of the secondary input geometry.

To Do:

  • Support multiple ray samples

Release Notes

interface version 1 —

2014-08-09

  • Minor help page fixes.

2014-07-17

Since poly soups turned out to be crazy fast to triangulate...

  • Added pre-triangulate Optimize option

  • Updated help page accordingly (with info on poly soups)

  • Minor UI c.c.'s

2014-06-19

  • Added Triangulate option

2014-03-26

  • Descriptive parm

2014-03-25

  • Added “Show Guide Geometry” toggle

  • Set 2nd input as reference

2014-02-19

Added “Stick” mode.

2013-12-13

Friday the 13th: Updated to H13 (hopefully).

2013-08-14

Added “Import Attributes from Hits” (experimental).

2013-08-03

First version.

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