Creep SOP

From TouchDesigner 088 Wiki

Summary

The Creep SOP lets you deform and animate Source Input geometry along the surface of the PathInput geometry.

PythonIcon.png creepSOP_Class

Parameters

Initialize - The Source Input is Translated, Rotated and Scaled so as to complete the given options listed below.

  • Fill Path - Values are computed that stretch or shrink the input geometry to the full length and width of the Path Input geometry. These values are placed in the nine transform fields at the bottom of the SOP.
  • Keep Proportions - Similar to above, but the values are initialized so as to minimize distortion of object geometry.

Translate /tx /ty /tz - Translate the Source Input Creep geometry on the surface of the Path Input.

  • /tx - Translate the Source Input along the Path Input's U parameter
  • /ty - Translate the Source Input along the Path Input's V parameter
  • /tz - Translate the Source Input along the Path Input's W parameter (elevation above/below Path)

Rotate /rx /ry /rz - Rotate the Source Input creep geometry on the surface of the Path Input.

  • /rx Rotate the Source Input along the Path Input's U parameter
  • /ry Rotate the Source Input along the Path Input's V parameter
  • /rz Rotate the Source Input along the Path Input's W parameter

Scale /sx /sy /sz - Scale the Source Input creep geometry on the surface of the Path Input.

/sx /sy /sz

The above three transform fields set the translation of the input geometry along the rows (U) and columns (V) of the Path. A creep translate of 0.5, -0.5, 1 puts the source in the middle of the path, one unit away from it. For scaling, a source of 0.2 0.3 in size will span 20% of the columns, and 30% of the rows on the Path.

Inputs / Geometry Types

The geometry of the Source SOP is crept along the path of the Path SOP. The path type can be any primitive, but should define a surface (e.g. NURBS surface, primitive tube, etc.). Curve paths (circles, polygons, etc.) will squash the source geometry's height. This SOP will transforms all vector attributes, even of particles - the velocities will be altered to reflect the transformation that creep does.

Note: NURBS surfaces might distort the crept geometry due to the non-uniformity of their U and V knot sequence. If the knots are not laid out uniformly (as in the case of a NURBS spline), knots closer together will squash the crept geometry in the corresponding surface region.

The Grid, Skin, Sweep, Tube, and Sphere (using Unique Points at Poles if polygons are used) SOPs are some of the SOPs that produce usable Meshes.

The Source Input SOP's geometry is wrapped onto the Path's, and the position and orientation of the Source on the Path is controlled by the nine fields that appear at the bottom of the SOP: Translate, Rotate, and Scale xyz.

The Z translate, Z scaling and X/Y rotation of the Source to the Path depends on the surface normals of the Path's geometry.

Uses / Works in Relation With

Creeping the starting profile for a filleted tube onto a surface can be accomplished with this SOP. Use a Transform SOP or Copy SOP to scale and translate the crept profile generating a series of cross-sections to skin with the Skin SOP.