Visual Effects Vol. 2

[GefullteTaubenbrust2]

This PR seeks to improve the visuals of Luanti through improvements to existing effects and addition of new ones (pertains to point 2.1 of the roadmap). To this end, shader code, and to a lesser extent engine code is modified.

List of changes

Adjustments to effects from #14610 and others:

• Translucent foliage sees some improvements to consistency and reduced artifacts
• Water reflections now work without waving water enabled
• Water reflections see some changes to correct for low alpha
• The (still placeholder) specular maps are improved
• The minimap shader is pixelated
• Made depth attenuation in volumetric lighting optional
• Made tinted fog optional

New effects:

• Added gamma setting
• Vignette as part of the second stage shaders
• ASL CDL color grading
• Tinted sunlight
• Adjustable artificial light color (global, not per node :( )

Lua API additions

• lighting.vignette controls the second stage vignette.
  • dark how bright the darkest part of the vignette is, default: 0.3.
  • bright how bright the brightest part of the vignette is, default: 1.1.
  • power controls the blending between dark and bright, default: 1.1.
• lighting.cdl controls the color grading decision list.
  • The output color follows the formula out = pow(in * slope + offset, power).
  • Default: { slope = { x = 1.2, y = 1.0, z = 0.8}, offset = { x = 0.0, y = 0.0, z = 0.0 }, power = { x = 1.25, y = 1.0, z = 0.9 } }.
• lighting.volumetric_light.beta_r0 controls the absorbance of the atmosphere for volumetric light and tinted sunlight effects.
  • Default: { x = 3.336e-01, y = 8.754e-01, z = 1.953 }.
  • The default is reasonable for most purposes, but this can be used to create sunrises/sunsets of arbitrary color.
  • An absorbance of zero { x = 0, y = 0, z = 0 } is equivalent to disabling tinted sunlight, except it also applies to volumetrics.
• lighting.artificial_light Controls the color of artificial light, default: { r = 133, g = 133, b = 133 }.
• lighting.foliage_translucency controls the strength of the translucent foliage effect, default: 1.5.
• lighting.specular_intensity controls the strength of the specular reflection effect, default: 1.5.

Settings

Name	Technical Name	Location	Type	Default
Tinted sunlight	enable_sun_tint	Effects>Dynamic Shadows	bool	false
Gamma	secondstage_gamma	Effects>Post Processing	float	1.6
Color grading	enable_color_grading	Effects>Post Processing	bool	false
Volumetric Depth Attenuation	enable_volumetric_depth_attenuation	Effects>Post Processing	bool	false
Tinted fog	enable_tinted_fog	Effects>Other Effects	bool	false
Bump maps	enable_bumpmaps	Effects>Other Effects	bool	false

Screenshots

To do

This PR is ready for review.

How to test

For most features, simply change the game settings. Of course, the game you use should support dynamic shadows and volumetrics. An example for the Lua controls is shown below:

player:set_lighting({
    artificial_light = { r = 140, g = 120, b = 100 },
    cdl = { offset = { x = 1, y = 1, z = 1 }, slope = { x = -1, y = -1, z = -1 }, power = { x = 2, y = 2, z = 2 } },
    vignette = { dark = 0, bright = 2, power = 0.5 },
    volumetric_light = { beta_r0 = { x = 2, y = 1, z = 0.5 } },
    foliage_translucency = 4.0, 
    specular_intensity = 4.0
})

This should produce inverted colors with color grading enabled, an exaggerated vignette, very bright reflections and foliage, blue sunsets and yellow artificial light.

[MisterE123]

Would it be a good idea to add server/mod control for the noise parameters of waving water in this PR?

Currently it's all client-side but the wave parameters, especially with reflections, are definitely part of the look-and-feel of a game and also relate to current weather conditions.

[GefullteTaubenbrust2]

Would it be a good idea to add server/mod control for the noise parameters of waving water in this PR?

Currently it's all client-side but the wave parameters, especially with reflections, are definitely part of the look-and-feel of a game and also relate to current weather conditions.

Hmm, good point. I mean this is something that was client controlled before, but it could make sense to have it be controlled from the server side instead. I'd like to know what others think about this as well.

[lhofhansl]

Would it be a good idea to add server/mod control for the noise parameters of waving water in this PR?

Yes, but I'd prefer a separate PR. The smaller a PR is, the easier it is to review and faster it will get merged.

[lhofhansl]

I think I asked that before (somewhere?)... What is the advantage of a shader based vignette effect over using a HUD image? (https://github.com/bas080/minetest_vignette)

[lhofhansl]

Looks like I cannot apply this as a patch (to master).

[GefullteTaubenbrust2]

I think I asked that before (somewhere?)... What is the advantage of a shader based vignette effect over using a HUD image? (https://github.com/bas080/minetest_vignette)

Yeah this conversation is buried somewhere on the Vol. 1... The HUD image has the disadvantage that it is rendered over the second stage, so there are quite visible banding artifacts and effects like color grading are not applied to the vignette, which is not as nice.

[grorp]

just two more "surface level" comments (unfortunately not a proper review of the actual shader stuff)

[farooqkz]

I guess now the rebase is done and only merge is left?

[farooqkz]

@GefullteTaubenbrust2 Hey. After #16670 got merged, now you need to rebase again and fix conflicts.

Edit: Not a dev or regular contributor here. Just some Luanti fan happy to see these new features in game :)

[sfan5]

Note that a revert for 3020c19 also needs to be included in this PR.

[GefullteTaubenbrust2]

Sorry, I haven't checked on this in a while. I'll get right to it.

[sfan5]

I guess this needs another round of reviews? Or is there something left to be fixed?

[GefullteTaubenbrust2]

I guess this needs another round of reviews? Or is there something left to be fixed?

Everything should be addressed unless I missed something.

[farooqkz]

I do wish we could have this for 5.16 :)

[sfan5]

@GefullteTaubenbrust2 could you rebase this again?

[GefullteTaubenbrust2]

Sorry, I've been procrastinating a rebase for weeks now.