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.

emit_from_instance1

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

emit_from_instance2

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

emit_from_instance3

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:
grid_every_n
Contrast the above with this nicer tree

Here’s [a cruder?] approach using linearly interpolated arrays:
grid_every_n_1

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.

rotate_vector_around_X_axis