CHOP to SOP

Summary

The CHOP to SOP reads sample data from a CHOP and converts it into point positions and point attributes. This makes it complementary to the SOP to CHOP. The Channels created by the SOP to CHOP can be modified and then re-inserted into the SOP network via a CHOP to SOP.

This does what a Point SOP with a chopci() function can do, but is much faster.

By using point groups from the incoming SOP, the channels can be inserted only into the group's points.

When you want one component of an array, like the Y value of the point position, you need to put P(1) into the Attribute Scope.

The CHOP to SOP also supports custom attributes. If the user maps a channel to an attribute that is not found, that attribute is added to the points. Currently, all custom attributes are floats and of size = 1.

In it's default state it will attempt to replace the point positions (P) with the channels named tx ty and tz.

The channel and attribute scope are first expanded into individual names and matched on a 1 to 1 basis. If you are filling P it doesn't matter if you specify t[xyz] or tx ty tz, both will replace P(0) P(1) P(2), since that's what attribute P would expand to.

For example: Add custom attributes "Scale", "Twist" or "Roll" to the backbone's points with a CHOP to SOP.

Parameters

Group - Modify only the points within this point group. If blank, all points are modified. Accepts patterns, as described in: Pattern Matching.

CHOP - Specifies which CHOP Network / CHOP contains the sample data to fetch.

Method - The sample data fetch method:

• Static - Uses one channel for each attribute, and all points use this channel (the first point resides at index 0, the next at 1, and so on). The length of the channels should be at least the number of points modified.
• Animated - Uses one channel per attribute per point. The channels show the animation of each point's position/attribute values.

Channel Scope - The names to use to modify the attributes.

Attribute Scope - A string list of attributes to modify in the SOP. List of Common Attributes:

• P - Point position (X, Y, Z) - 3 values
• Pw - Point weight - 1 value
• Cd - Point color (red, green, blue, alpha) - 4 values
• N - Point normal (X, Y, Z) - 3 values
• uv - Point texture coordinates (U, V, W) - 3 values

See List of Attributes for a complete listing of attributes.

Organize by Attributes -

Mapping - Determines how the CHOP samples are mapped to the geometry points.

• One Sample to Each Point - The samples are simply mapped 1-to-1, each sample is mapped to the next point in order.
• Resample CHOP to Fit SOP - If there are more or less CHOP samples than points in the geometry, then the CHOP channels are resampled to interpolate values for all the geometry points.

Compute Normals - Creates normals on the geometry.

Compute Tangents - Creates tangents on the geometry.

Local Variables

None.

See Also

• Geometry CHOP