Creates a sticky object based on the UV’s of a surface, usually for parenting.
This tool creates an object which takes its transform from the world-space position of a UV point on a polygonal surface. You can then parent another object to the Sticky object to make the object follow the surface.
This is similar to the 
Rivet tool; however, this tool is more precise since you can attach the sticky anywhere on the surface and you can animate the position as well as the object. For example, you could animate a monkey riding on an elephant’s back while sliding across the surface trying to balance.
The Sticky Object gets its transform from the surface of a polygonal mesh. The mesh must also have texture coordinates that are used to determine the parameterization of the polygons.
Sticky Objects may be parented to other sticky objects. In this case they will parent their 2d UV transformation (both the UV offset and the rotation). If one parents sticky objects, the Fetch World Transform should be turned on.
The Sticky Geometry path determines the object to stick to. To stick objects to sticky geometry, you must parent the geometry you want stuck to the Sticky node.
For example to stick a sphere to a grid, make sure the grid has uv texture attributes, create a Sticky Object, set the Sticky Geometry to the grid, and parent the sphere to the Sticky Object.
Placing a sticky in the viewer
Parameters
Sticky
| Sticky Geometry | The SOP to stick the geometry to. |
| Attribute | The attribute name of the texture to use for the polygonal parameterization. |
| UV | The UV coordinates to evaluate the mesh at. |
| Rotation | The angle to rotate the local coordinate frame about the surface normal. It will only take effect when Orient to Surface is on. However, any other sticky objects parented to this one will inherit this rotation. |
| Orient To Surface | Whether the local orientation of the point should be used. The surface normal is used as the Z axis and the texture’s U axis is used as the Y axis. |
| Fetch World Transform | If this is set, the transform of the Sticky Geometry will be used. If not set, the parent transform of this node will be used. |
| Wrap in U/V | When not set, u and v values outside the range will be ignored. When it is set, they will be wrapped until they lie within the range. |
| U/V Range | This is the range of texture space to work within. Geometry whose texture coordinates lie outside this range will be ignored. |
| Assume UV Coordinates Unchanging | The sticky object builds a cache of the target surface’s texture coordinates. When this is set, the cache is kept even if the target’s geometry changes. |
| Clear UV Caches | The Sticky Object is conservative about rebuilding the UV information. This will force it to update the UV texture lookups. |
Render
| Display | Whether or not this object is displayed. Turn on the checkbox to have Houdini use this parameter, then set the value to 0 to hide the object, or 1 to show the object. If the checkbox is off, Houdini ignores the value. | ||||||||||||||||
| Set Wireframe Color | Use the specified wireframe color | ||||||||||||||||
| Wireframe Color | The display color of the object | ||||||||||||||||
| Viewport Selecting Enabled | Object is capable of being picked in viewport. | ||||||||||||||||
| Select Script | Script to run when the object is picked in the viewport. See select scripts . | ||||||||||||||||
| Cache Object Transform | Caches object transforms once Houdini calculates them. This is especially useful for objects whose world space position is expensive to calculate (such as Sticky objects), and objects at the end of long parenting chains (such as Bones). This option is turned on by default for Sticky and Bone objects. See the OBJ Caching section of the Houdini Preferences window for how to control the size of the object transform cache. | ||||||||||||||||
| Geometry Scale | Uniform scaling about the xyz axes. | ||||||||||||||||
| Display | Whether to display only the icon, only the axis, or both.
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| Control Type | Switches between the type of geometry to display.
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| Orientation | Used in conjunction with circle or plane primitives. Determines which circles or planes to display.
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| Shaded Mode | Determines whether to display the primitives as shaded objects or as wireframe objects.
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Examples
| StickyDonut | Load | Launch |
In this example, a donut is stuck to an animated sticky object on the surface of a grid. | |