OSPRay shadows accumulate

[aowen87]

Describe the bug

This is related to #3480 When rendering with OSPRay, shadows have some odd behaviors. When shadows are first enabled, the rendered shadows are fairly faint. If you click on the render screen once, the shadows get slightly darker. If you continue clicking, the shadows continue to get darker until they are fully black. The same behavior occurs when disabling shadows; they slowly reduce in intensity with each mouse click.

If you click and drag the render screen, this process seems to accelerate, and the result is that the shadows appear to suddenly get dark or suddenly vanish.

Helpful additional information (Please click check boxes AFTER submitting ticket)

• [ ] Did VisIt crash?
• [ ] Did you get wrong results?

Impact

• [ ] High - User productivity significantly degraded
• [x] Medium - User productivity partially degraded
• [ ] Low - User productivity trivially degraded

Likelihood

• [ ] High - occurrence is not specific to platform, data, config, a combination of operators, queries, etc.
• [x] Medium - neither low nor high likelihood
• [ ] Low - occurrence is specific to combination of multiple factors such as configuration, data, platform, etc.

Expected behavior

Shadows should not darken/lighten depending on independent mouse clicks; there should be some consistency, and they should really only change as the lighting changes.