Implement LensFlareEffect

[vanruesc]

Description

Implement a LensFlareEffect.

References:

• https://www.froyok.fr/blog/2021-09-ue4-custom-lens-flare/

Tasks

• Create LensFlareEffect.
• Create lens-flare demo.
• Add unit test.

Implementation Details

See #616 regarding flare/glare.

[kitaedesigns]

Leaving this here as a reference for a nice and customizable LensFlare postprocessing pass created by @ektogamat and @N8python.

https://github.com/N8python/nektoFlare

[ektogamat]

Thanks @kitaedesigns . This one is very performance oriented. It is not relying on raycasters to detect occlusion. Support more than a 100 instances without changing the fps

[shotamatsuda]

Hello! I recently created a lens flare effect based on the article mentioned, although it lacks starburst and anamorphism.
Source: https://github.com/takram-design-engineering/three-geospatial/blob/main/packages/effects/src/LensFlareEffect.ts
Demo: https://takram-design-engineering.github.io/three-geospatial/?path=/story/effects-lens-flare--basic

I’d happy to contribute if it’s relevant to this issue and aligns with your performance and feature goals.

[ektogamat]

Fantastic work @shotamatsuda !!! Congratulations!

[vanruesc]

That looks great 👍

@shotamatsuda Feel free to send a PR for v6 since it's already in that format. We can port it to v7 later.

[shotamatsuda]

Got it. It’ll take some time to refactor and bring it in line with the other codes, but I’ll be sure to make a PR for this. (Glad because I was looking for a good place to integrate a pure post-processing effect.) 🌟

[vanruesc]

@shotamatsuda FYI: please only create a new v6 manual demo for testing purposes. The older v6 demos are obsolete.

(Background info: #324 (comment))