volumeFog node

Use volume fog to shade the density of a volume shape.

This node is MP safe

Node name	Parents	Classification	MFn type	Compatible function sets
volumeFog	shadingDependNode	shader/volume/fog	kVolumeFog	kBase kNamedObject kDependencyNode kVolumeFog

Attributes (84)

The following quick index only shows top-level attributes (too many attributes to show them all): axialDropoff, color (3), colorRamp (6), colorRampInput, density, densityMode, dropoffMethod, dropoffShape, dropoffSubtract, edgeDropoff, farPointObj (3), farPointWorld (3), glowIntensity, illuminated, incandescence (3), lightDataArray (14), lightScatter, matrixWorldToEye, matteOpacity, matteOpacityMode, outColor (3), outGlowColor (3), outMatteOpacity (3), outTransparency (3), pointObj (3), pointWorld (3), rayDirection (3), transparency (3)

Long name (short name) Type Default Flags

axialDropoff (axd) float 0.3

Defines how quickly the density drops off down the axis of a cone.

color (cl) float3

Color is the basic color of the volume(when not otherwise defined).

colorR (cr) float 0.9

color red value

colorG (cg) float 0.9

color green value

colorB (cb) float 0.9

color blue value

colorRamp (crm) compound n/a

This defines the color ramp used by the colorRampInput, which defines a mapping of this ramp to the volume.

colorRamp_Position (crmp) float 0.0

Position of ramp value on normalized 0-1 scale

colorRamp_Color (crmc) float3

Ramp color at the sibling position

colorRamp_ColorR (crmcr) float 0.0

Ramp red channel value at the sibling position

colorRamp_ColorG (crmcg) float 0.0

Ramp green channel value at the sibling position

colorRamp_ColorB (crmcb) float 0.0

Ramp blue channel value at the sibling position

colorRamp_Interp (crmi) enum 0

Ramp Interpolation controls the way the intermediate values are calculated. The values are:

None

Linear: The values are interpolated linearly in RGB color space.

Smooth: The values are interpolated along a bell curve, so that each color on the ramp dominates the region around it, then blends quickly to the next color.

Spline: The values are interpolated with a spline curve, taking neighboring indices into account for greater smoothness.

colorRampInput (cri) enum 0

This determines the input to the color ramp. If transparency is used, then the value used from the colorRamp is relative to the current transparency within the volume. More transparent regions will use the color at the left of the ramp and totally opaque regions will have the color at the right. For concentric mapping the distance to the volume center determines color from the ramp. Y Gradient selects the color based on the position along the y axis. If Ignore is set then the color parameter is used instead of the color ramp.

density (dns) float 1

the density or opacity of the fog

densityMode (dmd) enum 1

Determines if the density is defined in worldspace or objectspace. Objectspace density preserves the look when an object is scaled.

dropoffMethod (drm) enum 0

Defines the the way the edge dropoff is performed Scale Opacity multiplies the overall density by the dropoff value, causing a uniform change in transparency. Subtract Density subtracts the dropoff value multiplied by the Dropoff Subtract value from the density. This is primarily useful when the density or transparency is textured. Low density regions will become completely transparent, while high density regions will not be affected much. This can help preserve the character of a pluffy cloud, for example.

dropoffShape (dos) enum 0

Defines a shape to use to define an outer boundary for creating a soft edged volume. If one is rendering a box volume then Cube should match the edges of the volume. Likewise for Sphere and Cone volumes. LightCone is different from Cone in that the fade does not occur near the point of the cone.

dropoffSubtract (drs) float 1.0

This is the maximum amount of density subtracted from the volume when Dropoff Method = Subtract Density. If the volume density is 1.0 and Dropoff Subtract is 1.0 then the edge of the volume will be completely transparent.

edgeDropoff (edr) float .5

Defines the rate at which the density drops off towards the edge defined by the Dropoff Shape.

farPointObj (fo) float3 1.0, 1.0, 1.0

The end of the volume interval in world space.

farPointObjectX (fox) float 0.0

The x-component of the object space far-position.

farPointObjectY (foy) float 0.0

The y-component of the object space far-position.

farPointObjectZ (foz) float 0.0

The z-component of the object space far-position.

farPointWorld (fw) float3 1.0, 1.0, 1.0

The end of the volume interval in world space.

farPointWorldX (fwx) float 0.0

The x-component of the world far-position.

farPointWorldY (fwy) float 0.0

The y-component of the world far-position.

farPointWorldZ (fwz) float 0.0

The z-component of the world far-position.

glowIntensity (gi) float 0.0

Glow Intensity is 0 by default, meaning that no glow is added to the material. As this is turned up, the material seems to 'glow' with a faint halo of light around it.

Note that this is different from the Incandescence attribute in a few important ways. First, glow is added as a post-process at the end of rendering. (Incandescence just makes the surface appear brighter.) Second, glow adds a halo, which incandescence does not.

illuminated (il) bool false

If Illuminated is turned on then lights will be computed for the fog. The lighting happens for each volume span as determined by the volume samples parameter on the geometry.

incandescence (ic) float3

Incandescence makes a material appear opalescent, as if it were emmitting light itself, such as lava or a phosphorescent moss. A slight touch of incandescence on vegetable matter, for example, can make the vegetation look alive.

By default, the color is black, which has no effect on the surface.

Note: although incandescence makes a surface appear to glow, it does not actually act as a source of light in the scene.

See also Glow Intensity.

incandescenceR (ir) float 0.0

incandescence red value

incandescenceG (ig) float 0.0

incandescence green value

incandescenceB (ib) float 0.0

incandescence blue value

lightDataArray (ltd) lightData NULL

The lighting information this node computes.

lightDirection (ld) float3

The light direction.

lightDirectionX (ldx) float 1.0

The x component of the direction.

lightDirectionY (ldy) float 1.0

The y component of the direction.

lightDirectionZ (ldz) float 1.0

The z component of the direction.

lightIntensity (li) float3

The light intensity (it is a color).

lightIntensityR (lir) float 1.0

light intensity red value

lightIntensityG (lig) float 1.0

light intensity green value

lightIntensityB (lib) float 1.0

light intensity blue value

lightAmbient (la) bool true

The boolean that indicates if the light has an ambient component.

lightDiffuse (ldf) bool true

The boolean that indicates if the light has a diffuse component.

lightSpecular (ls) bool false

The boolean that indicates if the light has a specular component.

lightShadowFraction (lsf) float 0.0

The visibility fraction to the light. value is in [0,1]

preShadowIntensity (psi) float 0.0

The light intensity without taking shadow into account.

lightBlindData (lbd) addr 0

The light blind data.

lightScatter (lsc) float 1.0

This is the amount that the fog scatters light in all directions. As it approaches zero the fog tends to scatter light more and more in a directional fashion, resulting in halos around light sources.

matteOpacity (mog) float 1.0

Matte Opacity is used (along with Matte Opactiy Mode) to affect how the matte (i.e. alpha channel or mask) for this material will be calculated. See Matte Opacity Mode above for full details.

matteOpacityMode (mom) enum 2

Matte Opacity Mode controls how the system will use the Matte Opacity attribute (below). When you are rendering with a matte (i.e. an alpha channel, or mask), these two attributes are used to control how this material will show up in the matte. This is useful if you will be compositing your rendered images later on.

There are three settings, used for different purposes:

Opacity Gain

Solid Matte: This is like Opacity Gain, except that the normally-calculated matte values are ignored in favor of the Matte Opacity setting. The entire matte for the object is set to the value of the Matte Opacity attribute. If there are transparent areas on the object, their transparency is ignored in the matte. Use this setting to composite an object with transparent parts, when you do not want the background to show through them.

Black Hole: The value of Matte Opacity is ignored, and all the matte for this material is set to be transparent. Use this when you are creating substitute geometry in a scene, which is standing in for objects in a background image that you will be compositing with later. Your stand-in objects will 'punch a hole' in the matte. This allows other computer-generated geometry to pass behind your stand-in objects. Later, when foreground and background are composited, the results will be correct, with the background object showing through the 'black hole' areas.

outColor (oc) float3 0.0, 0.0, 0.0

Out Color. Connect another attribute to this to control the color of the volume shader.

outColorR (ocr) float 0.0

Out Color red value

outColorG (ocg) float 0.0

Out Color green value

outColorB (ocb) float 0.0

Out Color blue value

outGlowColor (ogc) float3

Out Glow Color is the final output glow color from this node (if this node is glowing)

outGlowColorR (ogr) float 0.0

out glow color red value

outGlowColorG (ogg) float 0.0

out glow color green value

outGlowColorB (ogb) float 0.0

out glow color blue value

outMatteOpacity (omo) float3 1.0, 1.0, 1.0

Out Matte Opacity. Connect another attribute to this to control the opacity of the material's matte (alpha) channel.

outMatteOpacityR (omor) float 0.0

Out Matte Opacity red value

outMatteOpacityG (omog) float 0.0

Out Matte Opacity green value

outMatteOpacityB (omob) float 0.0

Out Matte Opacity blue value

outTransparency (ot) float3 0.0, 0.0, 0.0

Out Transparency. Connect another attribute to this to control the Shader's transparency. Higher values (that is, brighter colors) make the object more transparent; darker colors make it more opaque.

outTransparencyR (otr) float 0.0

Out Transparency red value

outTransparencyG (otg) float 0.0

Out Transparency green value

outTransparencyB (otb) float 0.0

Out Transparency blue value

pointObj (po) float3 0.0, 0.0, 0.0

The current start point of the volume interval in object space

pointObjX (pox) float 0.0

The x component of the current sample position

pointObjY (poy) float 0.0

The y component of the current sample position

pointObjZ (poz) float 0.0

The z component of the current sample position

pointWorld (pw) float3 0.0, 0.0, 0.0

The current start point of the volume interval

pointWorldX (pwx) float 0.0

The x component of the current sample position

pointWorldY (pwy) float 0.0

The y component of the current sample position

pointWorldZ (pwz) float 0.0

The z component of the current sample position

rayDirection (rad) float3

The ray direction.

rayDirectionX (rdx) float 0.0

The x component of the direction.

rayDirectionY (rdy) float 0.0

The y component of the direction.

rayDirectionZ (rdz) float 1.0

The z component of the direction.

transparency (t) float3

Transparency is the color transparency of the volume

transparencyR (tr) float 0.5

transparency red value

transparencyG (tg) float 0.5

transparency green value

transparencyB (tb) float 0.5

transparency blue value

matrixWorldToEye (wte) fltMatrix identity

The matrix that takes world space to eye space