Brief description on building Surface Constraint
with ICE in XSI 7

by Daniel Harjanto a.k.a misterdi

Phil Taylor kindly show his ICE Rigging compounds on Softimage Community Forum

Here is the video of "ICE Kinematics – Rigging Constraints"

Here is a brief description on the compound in attempt to re-build the Surface Constraint ICEgraph
Note that ICE Kinematics are totally unsupported by Softimage for this release. You can enable this by setting environment variable XSI_UNSUPPORTED_ICE_KINEMATICS on,
but you’re on your own!

Scene Setup
Required element for this setup

Objects needed:
Get a grid, by default its name is grid
Create a Cube, by default its name is cube
Get an empty pointcloud, by default its name is pointcloud.

Getting an ICETree

Steps:
Select the pointcloud, and hit Alt+9.
An ICETree editor will be opened

To start building the ICETree graph, make sure that pointcloud is in the right pane.
Click ICETree->Create->ICE Tree
There will be a single ICETree node created in the editor which will be the root of the ICETree graph

Get Location on the Surface

There might be several ways to get Location on Surface, here is an example of setting up options for user to choose:

Use Raycast method
Use Get Closest Location method

Each method will give different result.

Raycast method

Notes:

Raycast node has 2 output port, Location and Hit
Location : Location at which the ray hit the surface.
Hit : A Boolean indicating whether the ray actually hit the surface.

Location

Important value in Raycast node is Direction
Directiom : The direction of the ray as 3D Vector

Get Closest Location method

Notes:

Get Closest Location node has 2 output, Location and Found
Location : Location at the surface which has the shortest distance to input Position
Found : A Boolean indicating whether the location was found in the Cutoff Distance.
Location information can be used to get other information such as PointPosition, PointNormal etc.

Looking at those graph we found similarity on both input and output port, this suggest that it maybe worthed to combine those graph as a single graph sharing the input and output.

Creating Get Surface Location Compound

Combining the methods

Since we are planning to create a compound out of the ICEGraph, it's worthed to minimize exposed port whenever it is possible using Pass Through nodes.

Notes:

With Pass Through node, a single port can be exposed but connect the exposed port to multiple nodes
Using Select Case, select the output of multiple nodes and output a single result depend on Condition.
It is similar with using Switch/Case statement in JScript
Condition input port of Select Case node is an integer, and path to be processed named accordingly, for example

Condition value = 0, will use Case0 path
Condition value = 1, will use Case1 path
Condition value = N, will use CaseN path

Creating the Compound

Add 2 Get Data Node, and connect both Source input port to Result output port of Select Case node that connected to Location, and

Set one to get PointPosition
Set the other to get PointNormal

Select all nodes except "Get grid" and "Get cube.kine.global", and use ICETree->Compound->Create Compound.

Customize the Compound

Notes:

Expose ports and give descriptive name for those ports.
And if necessary also use other properties such as using combo box.
For example, for the Geometry Query input box, instead of having integer for Condition,
use "Raycast" and "Closest Location" is more helpful for user.
When user select "Raycast" it will pass 0 to the Pass Through node,
and when user select "Closest Location" it will pass 1