Particle Lighting seems weird.

[shaomeng]

The particle lighting seems weird, if not wrong. The test data is this one (/glade/p/cisl/vast/vapor/data/Source/DCP) and the following screenshots explains what's weird.

Note: the reference lighting effect pictures are from this website: https://www.cs.toronto.edu/~jacobson/phong-demo/.

Specular lighting seems weird

To illustrate the effect of specular lighting, let's turn off every other lighting and turn specular lighting to its full level, as the following screenshot shows.

However, this looks more like ambient lighting. A proper specular lighting on a sphere would look something like this:

Shineness is not strong enough.

Let's try to use the strongest shineness, as the following screenshot shows. However, each sphere is barely shining.

A properly lighted sphere, however, would give very obvious shining effect, as the following screenshot shows.

[shaomeng]

We agreed on 2 baselines regarding lighting:

1. Particles and flow renderers should use the same lighting model
2. Whatever lighting model is chosen, we should provide a correct implementation of it.

[sgpearse]

No slider should go to zero shininess should go to ~100.