Houdini - Constraints and anchor_id - Part 1

When Houdini builds a Constraint Network, as long as points have @name, it automagically connects points to the centroid of the object specified by @name.

[Left] We have a constraint network (in yellow). The points only have @name declared on them. [Right] Inside DOPs, Houdini finds the object, and smartly connects the bottom points to the centroid of the object. Which results in:

What we need is a way to tell Houdini which points on the target do we want each constraint point to be anchored to.

To do this, we declare i@anchor_id on the points.

[Above] The constraint points touching her body each have an i@anchor_id – which stores the @ptnum of the point that is on her body. Which is like telling Houdini: “this constraint point anchors point number x on the target”.

The “top” points have i@anchor_id = -1. Since they have an empty @name e.g. “world constrains” - it can be any number.

Inside DOPs, the Constraint Network now looks like what we want:

To summarize:

• constraints
• houdini