This introduces a number of "tools" to visualize a smoke sim in different ways.
Included changes are:
- Object (axis) aligned slicing.
- Single slice visualization.
- Transfer function based on a color ramp.
- Control of the apparent thickness of the volume.
- Visualize the velocity field as a set of needles or streamlines
The overall number of slices can be set on a "per voxel" (smoke resolution) basis, meaning that if the resolution is set to 32, there will be slice_per_voxel * 32 slices in total.