HDA Attachto

Attachto is a Houdini SideFX digital asset for adding points to polygons by clicking the LMB in the viewport.

Attachto creates points when the LMB is clicked in the viewport on polygonal geometry objects and attaches these points to the polygons on which they were created, inheriting all subsequent transformations of the parent polygons. By using with "CopyToPoints" SOP node this asset allows for quick and convenient attachment of instanced geometry to other polygonal geometry objects, creating groups, and controlling orientation and position relative to the parent objects.

• See the User Guide video here on YouTube.
• Documentation (description of all parameters and functions, example files).

Asset quick overview:

☑️ Features

• Tested in Houdini versions: 19.5, 20.0
• Object Space.
• Group and individual parameter settings
• Extracting transformation matrix from input polygons
• Control of the addition of newly created points to groups
• Control and randomization of the @pscale attribute for each created point
• Control of rotation axis and rotation angles and randomization of rotation angles when using the @orient attribute
• Control of position changing relative to the parent object
• Alignment of instanced geometric objects copied onto points along the surface of polygons

🏃 Quick guide how to use the Attachto

1. Connect the polygonal objects* to input1.
2. Select the HDA "attachto" in the Network View, select "Show Handle" in the selector and handle control menu.
3. Set the necessary parameters if required. Click the mouse to add points to the polygonal geometry object connected to input1 and displayed in the viewport.
   

* Requirements for incoming geometry:

• Does not work with packed geometry
• The polygonal object to which points need to be attached must contain a primitive attribute @xform with a transformation matrix4 for each primitive:
  • If you are using packed geometry, create the @xform attribute using the "getpackedtransform" function and unpack the packed polygons.
  • If you are using the "Transform" SOP node, enable the "Output Attribute" toggle, add the "attribpromote" SOP node, and transfer the detail attribute @xform to the primitives.
  • If you cannot create the @xform attribute on incoming primitives, add a "connectivity" SOP node before the asset, go to the "Incoming Geometry" tab, enable the corresponding toggle, and set the attribute name the same as specified in the "connectivity" SOP node.

💡 Tips for using

• If you already know the polygons to which you need to attach points, try to input only those into the asset, removing all others. This will increase efficiency and reduce the use of computational resources.
• Points are added quite quickly, and if you need to place a single point in a specific position, try not to move the mouse cursor during the click. If someone finds this control inconvenient to use, please let me know, and I will add control over the delays between adding points to the asset parameters.

For a detailed description of the parameters and functions, see for the asset page on GitHub or the full video user guide.

Download the example file contains simple settings for a quick asset test.