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Surface Luminance is a utility node that tells you the luminance (brightness) of a point on a surface as it is being rendered. This luminance takes into account all the light sources shining on the object, and the angle at which they shine on the object. It does not take into account the specular properties of the object itself, such as 'hotspots'.

You can use this node to make interesting shaders that change based on the light in the environment. Example: Say you are modelling a windscreen of a car, made of a special glass that becomes darker (more opaque) in bright light. To do this, create a Surface Luminance node, and connect its output to all three input channels of a Reverse node. Then connect the output of the Reverse node to the Transparency attribute of a shader. In the table below, important attributes have their names listed in bold in the description column.

This node is MP safe

Node name Parents Classification MFn type Compatible function sets
surfaceLuminance node utility/color kSurfaceLuminance kBase
kNamedObject
kDependencyNode
kSurfaceLuminance

Related nodes

blendColors, clamp, lightInfo, gammaCorrect, contrast, luminance, rgbToHsv, hsvToRgb, samplerInfo, setRange, resolution, renderQuality, renderGlobals, renderGlobalsList, baseShadingSwitch, singleShadingSwitch, doubleShadingSwitch, tripleShadingSwitch

Attributes (20)

lightAmbient, lightBlindData, lightDataArray, lightDiffuse, lightDirection, lightDirectionX, lightDirectionY, lightDirectionZ, lightIntensity, lightIntensityB, lightIntensityG, lightIntensityR, lightShadowFraction, lightSpecular, normalCamera, normalCameraX, normalCameraY, normalCameraZ, outValue, preShadowIntensity

Long name (short name) Type Default Flags
normalCamera (n) float3 0.0, 0.0, 1.0 outputinputconnectablehidden
The input normal
normalCameraX (nx) float 0.0 outputinputconnectablehidden
The X component of the input normal
normalCameraY (ny) float 0.0 outputinputconnectablehidden
The Y component of the input normal
normalCameraZ (nz) float 0.0 outputinputconnectablehidden
The Z component of the input normal
lightDataArray (ltd) lightData NULL arrayinputconnectablehidden
The lighting information this node computes.
lightDirection (ld) float3 inputconnectablehidden
The light direction.
lightDirectionX (ldx) float 1.0 inputconnectablehidden
The x component of the direction.
lightDirectionY (ldy) float 1.0 inputconnectablehidden
The y component of the direction.
lightDirectionZ (ldz) float 1.0 inputconnectablehidden
The z component of the direction.
lightIntensity (li) float3 inputconnectablehidden
The light intensity (its a colour).
lightIntensityR (lir) float 1.0 inputconnectablehidden
The red component of the intensity.
lightIntensityG (lig) float 1.0 inputconnectablehidden
The green component of the intensity.
lightIntensityB (lib) float 1.0 inputconnectablehidden
The blue component of the intensity.
lightAmbient (la) bool true inputconnectablehidden
The boolean that indicates if the light has an ambient component.
lightDiffuse (ldf) bool true inputconnectablehidden
The boolean that indicates if the light has a diffuse component.
lightSpecular (ls) bool false inputconnectablehidden
The boolean that indicates if the light has a specular component.
lightShadowFraction (lsf) float 0.0 inputconnectablehidden
The visibility fraction to the light. value is in [0,1]
preShadowIntensity (psi) float 0.0 inputconnectablehidden
The light intensity without taking shadow into account.
lightBlindData (lbd) addr NULL inputconnectablehidden
The light's blind data.
outValue (o) float 0.0 outputconnectable
Out Value is the surface luminance of the surface being rendered.