AtmosphericStandard Material

Shader: Terrain/Scaled Planet (RimAerial) Standard

The AtmosphericStandard Material { } drives the Terrain/Scaled Planet (RimAerial) Standard shader — the scaled-space planet shader for atmospheric bodies, lit with Unity's Standard physically-based shading model. Like the plainer Atmospheric material it paints the planet's distant, low-LOD sphere from a single colour map and rings the limb with a view-angle rim glow that stands in for the soft halo of an atmosphere seen edge-on (the "aerial perspective"). The two materials accept exactly the same properties and draw the same rim; what differs is how the surface itself is shaded — here it is energy-conserving PBR specular, with image-based ambient and reflections supplied by Unity, rather than the older hand-rolled Blinn-Phong highlight.

In the stock system this material is used by Kerbin and Eeloo. (Eeloo has no atmosphere of its own, yet is still assigned this type; a body that wants no visible halo simply leaves its rim dark — see rimBlend and rimColorRamp below.)

If your body has no atmosphere, you can also use the plainer Vacuum material — it builds the surface the same way but has no rim at all. If you want a procedurally-banded gas giant rather than a painted surface, see the Gas Giant material, which has its own, brighter rim model.

The Standard scaled-planet shaders ship only with KSP 1.9 and later. On older KSP versions this type is unavailable; use type = Atmospheric instead.

We shall first see how to enable the material, then how the shader lights the surface and draws the rim, and finally discuss each group of properties in turn.

Enabling

Select the material by setting type = AtmosphericStandard in the ScaledVersion { } node. The Material { } node then accepts the properties listed below.

ScaledVersion
{
    type = AtmosphericStandard
    Material
    {
        // Surface maps
        texture = MyMod/PluginData/Kerbin_color.dds
        normals = MyMod/PluginData/Kerbin_normal.dds

        // Colour and specular response
        color     = 1, 1, 1, 1
        specColor = 0.5, 0.5, 0.5, 1
        shininess = 0.078125

        // Atmospheric rim
        rimPower     = 3
        rimBlend     = 1
        rimColorRamp = MyMod/PluginData/Kerbin_rim.dds

        // Resource-scanner overlay (optional)
        resourceMap = MyMod/PluginData/Kerbin_resources.dds
    }
}

How the surface is lit

The shader is a Unity Standard (specular workflow) surface shader with two KSP-specific pieces layered on top — one that adds surface relief, and one that paints the atmosphere. Because it is a true PBR model, the engine also supplies spherical-harmonic ambient, reflection probes, and proper energy conservation for free, rather than the single hand-rolled highlight of the legacy shaders:

1. Albedo and smoothness — texture is the colour map. Its RGB channels are the surface albedo (multiplied by color), and its alpha channel is a per-pixel smoothness mask: bright areas read as glossy, dark areas as rough and matte. The global shininess value scales that alpha, so the final per-pixel smoothness is texture.alpha × shininess. This lets a single texture vary glossiness across the surface (e.g. shiny seas against dull land).
2. Surface relief — normals is a tangent-space normal map that perturbs the lighting per pixel, so the body keeps fine surface detail when viewed from orbit even though the scaled-space mesh is smooth.
3. Atmospheric rim — a glow that fades in toward the planet's silhouette. Where the surface faces the camera head-on it contributes nothing; as the surface curves away toward the limb it brightens, reaching full strength right at the edge (rimFalloff = (1 − N·V)^rimPower). rimPower controls how tightly the glow hugs the limb and rimBlend scales its overall brightness. Its colour is read from rimColorRamp, a 1-D ramp indexed by the day/night terminator, so the sunlit limb and the dark-side limb can be tinted differently (a bright blue dayside haze fading to a dim nightside edge, say). The finished rim is then scaled by opacity.

Because this is a physically-based specular workflow, specColor is the surface's specular reflectance at normal incidence (its F0 colour) rather than a free-floating highlight tint — Unity uses it, together with the smoothness above, to drive both the direct specular highlight and the image-based reflections and ambient that the Standard model adds. Setting specColor to black removes the specular reflection entirely. There is no emission term beyond the rim — what you paint is what you get, lit by the local star and its surroundings.

A resourceMap overlay shares the rim's emission slot: the scanner colour is composited as lerp(rim, resourceRGB, resourceAlpha), so where the resource map is opaque it replaces the rim glow at that point, and where it is transparent the rim shows through untouched. The lit surface beneath is always added on top, so the overlay never hides the planet itself. The default all-black map contributes nothing.

Properties

The properties fall into five groups, which we shall take in turn:

1. Surface maps — the colour and normal textures that define the body's appearance.
2. Colour and specular — the tints and surface smoothness applied during PBR lighting.
3. Atmospheric rim — the view-angle halo and the ramp that colours it.
4. Resource overlay — the optional scanner map composited on top.
5. Opacity — the rim fade scalar.

Surface maps

Property	Format	Description
texture	File Path	The scaled-space colour map. RGB = surface albedo (multiplied by color); alpha = per-pixel smoothness mask (scaled by shininess). Also accepts the alias mainTex. Default "white".
mainTexScale / mainTexOffset	Vector2	Tiling and offset of the colour map.
normals	File Path	Tangent-space normal map, stored in DXT5nm packing (X in the alpha channel, Y in green, Z reconstructed). Also accepts the alias bumpMap. Default "bump" (flat).
bumpMapScale / bumpMapOffset	Vector2	Tiling and offset of the normal map.

Colour and specular

Property	Format	Description
color	Color	Master diffuse tint multiplied into the colour map's RGB before lighting. The alpha is unused. Default (1, 1, 1, 1).
specColor	Color	Specular reflectance at normal incidence (the PBR F0 colour), used together with the surface smoothness to drive both the direct highlight and the image-based reflections. Set to black to remove specular reflection entirely. Default (0.5, 0.5, 0.5, 1).
shininess	Decimal	Global smoothness scale. The final per-pixel smoothness is texture.alpha × shininess, so 1 passes the texture's gloss mask through unchanged and lower values make the whole surface rougher and more matte. The shader declares the valid range as [0.03, 1]. Default 0.078125.

Atmospheric rim

Property	Format	Description
rimPower	Decimal	View-angle rim falloff exponent. Larger values concentrate the glow into a thinner ring at the limb; smaller values spread it across a broader band. Default 3.
rimBlend	Decimal	Master brightness multiplier on the sampled rim colour, applied before the opacity fade. Set to 0 to suppress the rim entirely. Default 1.
rimColorRamp	File Path	1-D colour ramp that tints the rim, indexed across the day/night terminator so the lit and dark limbs can be coloured differently. Default "white".
rimColorRampScale / rimColorRampOffset	Vector2	Tiling and offset of the rim colour ramp.
Gradient	Gradient	The rimColorRamp, but defined explicitly as a gradient instead of a texture. Each entry's left value is the position along the terminator from 0 (lit side) to 1 (dark side), and the right value is the rim colour there.
localLightDirection	Vector4	Object-space sun direction used to compute the terminator coordinate for the ramp. Marked [PerRendererData] and overwritten every frame by KSP's scaled-space lighting controller, so a config value has no lasting effect. Default (1, 0, 0, 0).

Resource overlay

Property	Format	Description
resourceMap	File Path	Resource-scanner overlay texture. Composited into the emission as lerp(rim, resourceRGB, resourceAlpha): opaque pixels replace the rim glow, transparent pixels leave it alone. Default "black" (contributes nothing).
resourceMapScale / resourceMapOffset	Vector2	Tiling and offset of the resource map.

Opacity

Property	Format	Description
opacity	Decimal	Master strength of the rim emission, range [0, 1]. It scales the rim glow only — not the lit surface (which always renders opaque), nor the resource overlay (which composites at full strength regardless). Default 1.

Notes

• opacity is marked [PerRendererData] and is driven at runtime by the scaled-space fader, which Kopernicus attaches to every non-star body with its floatName bound to _Opacity. As the camera crosses the fadeStart and fadeEnd altitudes the fader sweeps this value, fading the atmospheric halo with the transition. A static config value is therefore normally left at its default of 1.
• localLightDirection is likewise [PerRendererData] and rewritten each frame, so although the loader exposes it as a config field, setting it has no lasting effect — it exists so KSP can keep the rim ramp tracking the real Sun as the planet rotates and orbits.
• Unlike the plain Atmospheric shader, whose rim is keyed to the body's smooth geometric normal, this build computes the rim's view-angle term against the normal-mapped surface normal — so surface relief feeds the limb glow as well as the lit surface, though the effect is subtle at the grazing angles where the rim is brightest.
• The shader requires mesh tangents for its normal mapping — the scaled mesh Kopernicus generates already provides them. A custom mesh without tangents will render with broken normals.
• The shader has no shadow-casting pass of its own; it delegates shadow casting to its Standard fallback (which also takes over wholesale if the shader fails to compile). It supports only Unity's modern single-pass deferred path, not the legacy two-step prepass — invisible to config authors, but the reason the lit result matches across rendering paths.