Improve Displacement Implementation

[AlexeyAdamitsky]

I like the LuxCore render. It's progressing really well and getting better and better.

I want to offer a suggestion how to improve recent Height Displacement implementation.

What is the issue?

The issue is how displacement is calculated currently. It calculates displacement from 0 to 1 where 0 is no displacement and 1 if full strength of displacement.

The displacement map I used for testing.

As a result we gets this:

You see that it's calculated from surface normals only in positive (1) direction.

To compensate for this we need to define Midlevel where 50% gray is neutral or 0 point displacement. Everything less than 50% gray will push displacement in a negative direction and everything that is greater than 50% gray will push displacement in positive direction.

To make it work correctly you can use Offset of the Height Displacement node:

Now it works as expected:

Well, not really, because if we decide to change the Scale to let's say 2 our Midpoint will shift.

Now we need to recalculate our Offset for our Midpoint like this: Offset = Scale * -0.5 Ok. Let's do this.

Now we corrected our Midpoint Offset.

But to recalculate it every time is a terrible workflow. It's a lot of manual work.

It could be made easier with a math nodes. But there is no way to feed the values to Height Displacement node:

Still, even with exposed values and math nodes solution it's a bad workflow. You need to recalculate Offset for Midlevel each time and you go into negative numbers to fix the Offset which is a bad UX.

Proposition

1. Expose Scale and Offset value of the Height and Vector Displacement nodes.
2. Implement the Cycles' way to control displacement where you define the Midlevel and not Offset. Set nodes Midlevel to default 0.5 which will be 50% gray point or 0 displacement.

You can try my test scene to see what the issue is: Displacement.zip

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