Using ICE to do UV remapping on instances

I was playing around with Softimage, trying to set up a puzzle:
At first, I was using actual geometry and snapping to put together the puzzle, but then (after watching a Cinema4D tutorial that used the Cloner to assemble the pieces) I decided to use ICE to position the puzzle pieces. Halfway through that, I realized that the texturing was going to be a problem. There doesn’t seem to be an easy way to apply a texture to multiple ICE instances, and then make the texture stick when the instances fly away.

After trying a bunch of stuff (and crashing a lot), I took a look at the UV Remap parameters on the Image node:

Then I created a 8×8 grid of 64 instances, and put all the possible min/max values in an array:
If you look at the point IDs, and the array, the pattern is pretty obvious, and it allows you to use modulo and integer division to index into the array and get the right min/max values for each instance.

Here it is in ICE:

Finally, the shader tree that gets the UV remap values and plugs them into the Image node:

[ICE] Converting integers to strings

Thanks to Mootzoid emTools, it’s easy to convert an integer to a string:
Note that you get padding too, so it’s easy to do things like generating replacements for the [Frame] token.
The emTools string compounds are convenience compounds:

For fun, I tried to create my own integer-to-string converter using the stock nodes. I did by dividing by 10 until the quotient (the result) was zero; with each division, I take the remainder and stick it at the front of the string. And by setting Max Repeat to 4, I get padding on my strings (so for integer 45 I get “0045”).
Note the use of Delay Set Data. The integer division compound uses Modulo and Division by Scalar. The 2char compound simply uses a Select Case to map a single digit to a string:

It did occur to me that I could do it all with a single Select Case :)
The catch is that the Select Case node has ten thousand cases.
That’s really slow when you create that node in an ICE tree (for example, by importing a compound that uses it). It also takes a long time to create ten thousand cases, even with a script.

case_node = Application.AddICENode("$XSI_DSPRESETS\\ICENodes\\SelectCaseNode.Preset", "pointcloud1.pointcloud.ICETree")
string_node = Application.AddICENode("$XSI_DSPRESETS\\ICENodes\\StringNode.Preset", "pointcloud1.pointcloud.ICETree")

Application.ConnectICENodes("{0}.case0".format( case_node.FullName ), "{0}.result".format( string_node.FullName ) )
Application.DeleteObj( string_node.FullName )
Application.SetValue("{0}.case{1}_string".format( case_node.FullName, 0), "{0:0>4}".format(0), "")
Application.SetValue("{0}.default_string".format( case_node.FullName, "9999", "")

for i in range(1,10000):
	Application.AddPortToICENode("{0}.case{1}".format( case_node.FullName, i-1), "siNodePortDataInsertionLocationAfter")
	Application.SetValue("{0}.case{1}_string".format( case_node.FullName, i), "{0:0>4}".format(i), "")

Emitting particles from instances

Suppose you want to emit particles from the instances in a point cloud. For example, suppose you have a point cloud of instances of a BigFish model, and you want to emit little fish from each BigFish instance.


One simple approach is to set up a point cloud on your master BigFish instance, and do the emitting there.


Then when you emit the point cloud of BigFish instances, use InstanceShape instead of Set Instance Geometry.


ICE: Getting the edge index of the longest edge

For each polygon, I want to get the EdgeIndex of the longest edge (ultimately, I want to get the midpoint of the longest edge for each polygon).

Being literal-minded, I started by getting the length of the longest edge for each polygon:
Here’s a Show Values to show it works:

From there, I hacked my way to the edge index:
The Show Values:

For my second try at getting the index of the longest edge, I stopped trying to go from the length back to the index. I think this is a little better approach:


ICE: Selecting every N points in a grid

Here’s a question from the Softimage mailing list, and what I would have answered (I didn’t answer, and I didn’t peek at the other answers either).

Given a 100×100 Grid point cloud, how would you do something to the following subsets of points?
[0,5,10, … 595] and [1000,5,10, … 1595]

For something like that, modulo is an obvious way to do it:
Contrast the above with this nicer tree

Here’s [a cruder?] approach using linearly interpolated arrays:

See also this for some compounds.

Rotating vectors around the global X axis

Another Rotate Vector example. This time, I rotate the points of a mesh around the global X axis. In short, the point positions are treated as vectors, and then rotated about the specified axis. Of course, this requires some conversion between coord systems, which is always fun :)

The bottom part of the tree is just for visualization.