Capture Region SOP
The Capture Region SOP defines capture region (cregion), which is a type of primitive which can be thought of as a modified tube primitive (a tube with half a sphere on either end). The hemispheres on the ends of the tubes are called "caps". Like any other primitive, each Capture Region has a primitive number and can be assigned primitive attributes. A Capture Region is simply a volume which is used to define the point capture weighting for a geometry. It is then animated to deform the geometry.
Capture Regions are always shown in wireframe (even in shaded mode) so that you can focus on the geometry for which the region will act on.
Parameters - Region Page
There are parameters to control the size, shape and position of the capture region. There are separate controls for the top and bottom half of the region. This allows you to edit one side of the bone at a time as you work through your character.
The Max/Min Weight parameter is used in the weighting of points. The closer a point is to the edge of the region, the smaller it's weight will be. By default the weight is 1 along the center axis of a region (more on this later), and 0 at the edge of the region. You can modify these weight extremities by through this parameter.
orient - ⊞ - Defines the direction axis of the region. Use Z axis when the region is inside a bone object.
- X Axis
- Y Axis
- Z Axis
t - ⊞ - Position of the center of the region.
theight - Height of the region from the centre to the top cap.
tcap - ⊞ - The X, Y, Z radii of the top/bottom hemisphere.
bheight - Height of the region from the centre to the top cap.
bcap - ⊞ - The X, Y, Z radii of the top/bottom hemisphere.
weight - ⊞ - Defines the weight of a point exactly on the centre line and edge of the region respectively. Point weights in-between are blended.
Parameters - Display Page
color - ⊞ - The Capture Region SOP<uses region colors for helpful feedback.
By default the region inherits the color of its containing object (via an expression).
How Weighting is Calculated
Weighting is based on distance to the center line of the region. The center line's length is the height of the tube and runs down its center. When viewed in cross-section, the distance is measured perpendicular to the center line for the tube section and radially for the hemisphere region. This scheme is shown below. The lines represent the distance of points along the edge of the region.
This weighting scheme gives continuous deformations to NURBS surfaces when the end cap section of one region is sized so that it touches the middle section of the next region, as shown below.
Capture regions shown with their containing bone objects.
Info CHOP Channels
Extra Information for the Capture Region SOP can be accessed via an Info CHOP.
Common SOP Info Channels
- num_points - Number of points in this SOP.
- num_prims - Number of primitives in this SOP.
- num_particles - Number of particles in this SOP.
- last_vbo_update_time - Time spent in another thread updating geometry data on the GPU from the SOP's CPU data. As it is part of another thread, this time is not part of the usual frame time.
- last_meta_vbo_update_time - Time spent in another thread updating meta surface geometry data (such as metaballs or nurbs) on the GPU from the SOP's CPU data. As it is part of another thread, this time is not part of the usual frame time.
Common Operator Info Channels
- total_cooks - Number of times the operator has cooked since the process started.
- cook_time - Duration of the last cook in milliseconds.
- cook_frame - Frame number when this operator was last cooked relative to the component timeline.
- cook_abs_frame - Frame number when this operator was last cooked relative to the absolute time.
- cook_start_time - Time in milliseconds at which the operator started cooking in the frame it was cooked.
- cook_end_time - Time in milliseconds at which the operator finished cooking in the frame it was cooked.
- cooked_this_frame - 1 if operator was cooked this frame.
- warnings - Number of warnings in this operator if any.
- errors - Number of errors in this operator if any.