Difference between revisions of "Frooxius Notes"

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Revision as of 00:36, 12 April 2020

Presented below are a section of notes copied from public conversations between Froox and the Neos community. They share useful hints and tips and answers to questions which may otherwise get lost. Eventually we will adapt these notes into full blown documentation but for now they may be helpful to you in the impromptu manner presented here. If you'd like to add/edit any entries please do so.


Render Queue Values

[11:04 AM] ToMo (DelVR): Heyo, doing some User interface design in Neos and in desperate need of render queue values, is this documented anywhere?

[11:06 AM] Frooxius: Hello! Neos is using the same Render Queue values as Unity, so you can use their reference for this.

[11:06 AM] ToMo (DelVR): Ah that's great! Cheers Froox

[11:06 AM] Frooxius: Essentially 2000 is opaque, 2450 alpha clip, 3000 transparent.

[11:06 AM] Frooxius: Some materials use a bit different ones though to get around certain issues.

[11:07 AM] ToMo (DelVR): Got it :poi_hisalute:

Computing Look Rotation

Frooxius on 2020-01-08: You can compute the rotation for look at very easily. Subtract global position of the looking object from the target, transform that as direction into the parent's space and then feed that to the LookRotation node to create a quaternion.

Driven Nodes Synchronization

The way Neos works is that anytime you make a change to any part of the data model (e.g. change position field or color) the change is synchronized from the person who changes it to everyone else.

However when you drive a field, you're essentially telling the system "Don't sync this value, it can be computed from other values/data that are synced", so everybody computes their own version on their end and saves a lot of network traffic.

Normally this works fine. But if you use the value itself in the computation (e.g. when simulating movement, you take the previous position and alter it), this is a problem, because you're using driven (non-synchronized) value to determine the new one. Any subtle differences in the computation will cause it to drift between users. This is a divergent feedback loop.

In such scenario you'd just use the write node to write a new value on the user controlling the vehicle for example and let Neos sync the new state to everyone else.

You can also have convergent feedback loops. SmoothLerp is actually example of one. It takes the existing value as input, new target and time. Even with subtle differences in calculation, it's still going to end up the same (new target, which is synchronized) value for everyone, so the feedback loop is ok in such scenario.

Gray Fog Volumes

@GearBell Switch it from Additive to Alpha. Then set the base color to gray with zero alpha (e.g. [0.5, 0.5, 0.5, 0] and the accumulation color to just alpha (e.g. [0, 0, 0, 1]). That way you have a static color whose alpha is being accumulated.

Child Order and Order Offset

@LeonClement Neos doesn't guarantee child order unless you specifically force it to. You can use the OrderOffset property to shift them around for now, make sure they all have one assigned, otherwise it'll default to sorting by allocation ID's when order is requested. Alternatively you need to specifically scan for the child you want, rather than depending on it being one with particular index.

PBR Material Textures

Aegis 2019-12-16:

   The metallic roughness map is comprised of the metallic which ranges from white(metallic) to black (non metallic), 
   the roughness using the alpha channel is from completely transparent(rough) to opaque(smooth)

Frooxius 2020-01-29:

   If you're using the PBR workflow then a lot of it will translate, but you have to make sure they're correct. 
   In Neos specular maps are combined with the gloss map, which is in the alpha of the specular.
   If you're using roughness map then you need to invert it to get smoothness.


The difference between Get Active and Get Active Self

[6:50 PM] Parker: Does anyone know the difference between, the LogiX nodes, "Get Slot Active" and "Get Slot Active Self"?

[6:55 PM] Frooxius: The active gets if it's currently active at all within the hierarchy. It can be inactive because one of its parents is inactive. The Active Self is more direct, tells you whether the slot it set to active or inactive itself.