Fix LODs of effects

[Garanas]

Description

Emitters can be quite expensive on the simulation. Up to 15% of the emitters in the game render up to extreme distance. These should be culled accordingly by introducing a sane LOD cutoff in their blueprint definition.

Course of action

Claim a few projectiles by making a comment in this pull request. This prevents people from doing the same projectiles. There are a few important factors to take into account:

LOD settings

In order to be consistent, make sure that your LOD settings are on 'high':

LOD of the emitter

Effects have an impact on the simulation speed. In particular the spawning of a particle has an impact. All effects have a LOD threshold set that determines at what distance from the camera it can generate particles. The Level of Detail threshold is used to cull entities when they contribute to no more than a few pixels. The value is called LODCutoff in the blueprint. When the LOD is not set the emitter always renders, regardless of the distance to the camera.

An example is the t1 Aeon artillery, as shown in the gif: their LOD cutoffs are set to -1 by default and the unit is widely used. Therefore it can easily take up 2% to 5% of the simulation speed (2ms to 5ms / tick) during a battle, even though you're too zoomed out to actually enjoy the graphics.

EmitterBlueprint {

       -- (...)

        -- values that we're interested in
	LODCutoff = -1,                 -- distance threshold to camera when rendering
	EmitIfVisible = true,           -- emits only if visible, this should typically be set to true
	CatchupEmit = true,           -- allows emitter to catch up if it becomes visible
	CreateIfVisible = false,       -- flag to only create if the emitter is visible upon creation. This should be set to false for effects with a long duration, such as a trail. Effects that happen often such as terrain effects can have this value set to true.

        -- (...)
    },

Finding the unit of an emitter

We make the assumption that you are using Visual Studio Code, as described in the setup of the development environment.

It could very well be that an emitter is not used in the base game. In that case you can set it to a default value of 300. Mods can still use those emitters.

• (1) Pick a set of emitters you intend to work on. Please post your selection in this pull request to prevent duplicated work. For this example, we'll stick to cybran_cruise_missile_launch_01_emit.
• (2) Assuming that you have the repository setup as your workspace, use CTRL + SHIFT + F to search through all the files. use the name of the emitter (without the path!) as a search argument. This will likely take you to an entry in /lua/EffectTemplates.lua. In this case, it is CIFCruiseMissileLaunchSmoke.
• (3) Repeat the search of the previous step but the with the new search argument: CIFCruiseMissileLaunchSmoke. This takes us to CIFMissileLoaWeapon where the effect is used as a muzzle flash.
• (4) Repeat the search of the previous step but the with the new search argument: CIFMissileLoaWeapon. This takes us to the unit class URS0304, which is the Cybran Strategic Missile Submarine.

The effect in question, on the water surface

Determine the settings

There are a few things that we need to take into account:

• Is the effect part of an projectile, or of a unit / weapon?
• What is the size of the effect as a whole?

If the effect is part of a unit / weapon then one can argue:

• LODCutoff: should be no higher than the LOD of the unit
• EmitIfVisible: should always be true
• CatchupEmit: should likely be false if the effect has a short duration (and the unit has a reasonable rate of fire)
• CreateIfVisible: should likely be true if the effect has a short duration (and the unit has a reasonable rate of fire)

If the effect is part of a projectile then one can argue:

• LODCutoff: Should be no higher than the LOD of the projectile, and if none is set then it depends on the size of the effect
• EmitIfVisible: should always be true
• CatchupEmit: if it is part of a trail then this should be true, if it is part of an explosion then it is questionable because those are quite short
• CreateIfVisible: if it is part of a trail then this should be false, if it is part of an explosion then it is questionable because those are quite short

Test plan

Make a branch based on this branch. Work on at most 20 emitters per branch. Once you've reached the threshold, make a pull request to merge back into this branch. Note that the default merge branch is set to deploy/fafdevelop. You'll have to adjust that.

Make sure to mention what units / weapons / projectiles use the emitters. Your changes will be easier to review with that information. If applicable a screenshot is appreciated too.

If you're unsure about anything you can discuss it in the #game-repository channel on the FAF Discord (after giving yourself the tester role in the #role-selection channel) or you can make a comment in this pull request.

Learning goals

Feel comfortable working on the repository and with Git in general.

Pull request progress

....

[Garanas]

Another pull request (#3719) defaults the LODs when they are not set (e.g, LODCutoff = -1.00) to 160. This is wrong for some effects - this pull request tries to fix that over time.

[Garanas]

I made a mistake and accidentally merged the branch of @MadMaxFAF 😞 .

[Garanas]

I'll update the track record once I'm back in a few days. For anyone else interested in working on this, please ask @MadMaxFAF which ones are still free.

[Garanas]

I've updated the original description with the remaining effects that have an infinite LOD cutoff - only 114 to go.

[Garanas]

With thanks to @MadMaxFAF for all the hard work 😃 .