Add a Preserve Orientation billboard property

[QbieShay]

Describe the project you are working on

Various VFX

Describe the problem or limitation you are having in your project

There is no adequate billboard mode to orient particles along their velocity while preserving the billboard

Describe the feature / enhancement and how it helps to overcome the problem or limitation

Add a billboard mode that projects the y axis on screen coordinates and uses that as a billboard angle

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

See above

If this enhancement will not be used often, can it be worked around with a few lines of script?

Need to re-implement by hand every time.

Is there a reason why this should be core and not an add-on in the asset library?

It's a common usecase and would improve usability.

[Calinou]

Related to #3968. This could be a good complement to that proposal, if someone can figure out a way to make this work in an universal way. In other words, there should be no requirement to manually specify a billboard axis for each material instance.

[QbieShay]

if someone can figure out a way to make this work in an universal way

I don't think universal is necessary. Particles orient based on the Y anyway ^^