Add 3D Particles Documentation

[and-rad]

This adds a new page to the documentation, covering 3D particle systems.

• Emitter properties
• ParticlesMaterial properties
  • Update: sphere surface
• Sub emitters
• Trails
  • Ribbons
  • Tubes
  • Skinned meshes (buggy, will be handled in separate PR)
• Collision
  • Box
  • Heightfield
  • SDF
  • Sphere
• Attractors
  • Box
  • Sphere
  • Vector field
• Complex emission shapes
• Turbulence (waiting to be merged and maybe improved)
• Viewport menu
  • Create emission points from node
  • Convert to CPUParticles3D
• Split docs into multiple pages

There is also this companion project that I used to create every screenshot used in the documentation:
https://github.com/and-rad/GodotDocParticles

[clayjohn]

You are definitely on the right track! This is looking great so far. I'm looking forward seeing to the rest of your progress

[and-rad]

Small heads up: It might look like I'm not making any progress lately, but that's just me waiting for 4.0 to become a little more feature-complete. I've had to redo some screenshots and gifs multiple times already since I started writing the docs because names and features have changed in the meantime. And with godotengine/godot-proposals#3588 probably getting implemented, I'll have to reorganize a lot of what's already written.

So in an effort to not have to do too many do-overs, I'm keeping the particle docs on the back burner, but I'll pick up the pace again as soon as 4.0 nears RC status.

[clayjohn]

@and-rad Sounds great! Thanks for letting us know. I look forward to when you return to this PR :)

[and-rad]

Gonna link godotengine/godot#61014 here. Even though it doesn't currently work, I have documented the feature as if it did. I expect it'll be fixed in time for the 4.0 release.

[Calinou]

Gonna link godotengine/godot#61014 here. Even though it doesn't currently work, I have documented the feature as if it did. I expect it'll be fixed in time for the 4.0 release.

This wasn't fixed for 4.0's release, so I suggest adding a warning block to mention that the feature won't work yet.

[Calinou]

The text is very good and complete, thanks a lot for going through this effort!

There are some changes that should be made to page and reference names though. Page names should use snake_case as per convention, and reference names should follow the file names (with parents included if there's possible ambiguity with other pages in the documentation).

Some page names should also be changed for better SEO, and so that they make more sense when viewed individually.

Here's a list of proposed changes (old → new):

• complexshapes.rst → complex_shapes.rst
• doc_complexemissionshapes3d → doc_3d_particles_complex_shapes
• creation.rst → creating_a_3d_particle_system.rst
• doc_particlecreation3d → doc_creating_3d_particle_system
• doc_particles3d → doc_3d_particles
• doc_particleprocessmaterial3d → doc_process_material_properties
• doc_particleattractors3d → doc_3d_particle_attractors (also rename the page to "3D particle attractors", and add a note that 2D particle attractors aren't implemented yet)
• doc_particlecollision3d → doc_particle_collision_3d
• doc_particleproperties3d → doc_particle_properties_3d
• doc_subemitters3d → doc_subemitters_3d (also rename the page to "Particle sub-emitters" with a hyphen)
• doc_particletrails3d → doc_particle_trails_3d
• doc_particleturbulence3d → doc_particle_turbulence_3d (also rename the page to "Particle turbulence"

[and-rad]

Done. I deviated from some of your suggestions when I felt it would improve consistency, but I think I got the important parts right.

[Calinou]

Thanks a ton!

[mhilbrunner]

Great work! PNGs need to be converted to WebP, but I can do that if you don't want to, seeing how long this been staying open :)

Edit: The PR actually contains WebPs, but PNGs too, we need to get rid of the latter.

[and-rad]

I'll take care of it. I switched to webp halfway through after the decision was made to use the format from now on, but I didn't bother converting the old stuff. I'll replace the gifs with webp too.

[Calinou]

I've amended this PR to document performance caveats of turbulence as per godotengine/godot#76501.

[Calinou]

Thanks a ton!