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This page provides i= nformation on the Voxel Shader component.
The Voxel Shader node is used to shade Fire/Smoke simulations and meshes= in a single Simulator.
Phoenix has multiple rendering modes that can be divided into two t= ypes: Volumetrics and Surfaces. The volumetric modes are used for fire and = smoke. 3ds Max materials can't be used to shade volumetrics because th= ey don't have surfaces. Instead their shading is described in the Volumetric Options ta= b. Unlike the volumetric modes, in surface modes the Simulator behaves just= as any regular geometry - 3ds Max materials can be applied to the Simulato= r and there is no need for a dedicated shader.
Voxel Grid - Specifies the Phoenix Simulator or V-Ray V= olume Grid from where the voxel grid data will be read.
Volumetric Options... =E2=80=93 Opens the = Volumetric Render settings window which contains the following rollouts:
When the Pin icon is enabled, the Volumet= ric Render Settings window will remain open even after deselecting the Simu= lator, Voxel Shader, or V-Ray Volume Grid.
The option's default state= is set to "Pinned", but if you need to change its behavior, you can do so = from the Phoenix= FD Global Preferences menu.
= p>
Step % | rendstep =E2=80=93 Specifie= s the ray marching step of the camera rays as a percentage of the cell size= . As the renderer traces rays through the Simulator, this value controls ho= w often to read information from the Grid. If this value is more than 100, = some cells will start getting skipped and artifacts may appear. Usually you= don't need to lower this below 90%, unless you use render curves or textur= e maps for the Fire or Smoke opacity or color - in these cases you might ne= ed to lower the step in order to capture the details which are smaller than= a voxel, otherwise these details will either be skipped or will render ver= y noisy. However, decreasing the step will make the render slower.
Shadow Step % | rendshadstep = =E2=80=93 Specifies the ray marching step of the rays used to evaluate the = lighting (shadow rays) as a percentage of the Cell Size. Usually, this valu= e can be higher than Step %, as generally shadows will no= t need so much detail. Increasing the Shadow Step % = will also speed up rendering performance, particularly with dome and area l= ights.
Border Fade | borderFade =E2=80= =93 Makes the content near the Grid's boundaries more transparent to preven= t sharp edges from being rendered. This parameter controls how far from the= boundaries the transparent effect should start, in Scene Units.
Heat Haze | heathaze, hhfac= tor =E2=80=93 Traces the ray changing direction according to the = gradient of the Surface channel. A value of 1 corres= ponds approximately to the normal heat haze in the air caused by the temper= ature. If smoke or another channel is selected as the source, a larger valu= e might be necessary to achieve a visible result. A value of 0 produces no = heat haze.
Sampler Type | sampler =E2=80= =93 Determines the blending method between adjacent grid voxels. Used = to balance between rendering speed and quality.
Box =E2=80=93 Displ=
ays voxels as cubes. There is no blending between neighbor voxels. This is =
the fastest mode.
Linear =E2=80=93 Linear blending=
occurs between neighbor voxels to smooth out the fluid's look. Sometimes t=
his mode may unveil the grid-like structure of the fluid. Up to 20-30% fast=
er than the Spherical option.
Spherical=
strong> =E2=80=93 Uses special weight-based sampling for the smoo=
thest looking fluid. With increasing resolution, the visual advantage of th=
is method over the Linear method becomes less notice=
able.
Cutter Geometry | usegizmo, gizmo =E2=80=93 When enabled, rendering will occur only ins=
ide the selected geometric object's volume. If Fire Lights are enabled=
, only those inside the cutter will be rendered. Note that the Cutter Geometry will not work when the Render as Geom=
etry option is enabled.
Invert Cutter | invgizmo =E2=80= =93 When enabled, rendering will occur only outside of the render cutter. T= his is not the same as a cutter with inverted geometry because any rays tha= t do not intersect the cutter will be shaded as well.
<= /span>Render as Geometry | geommode = =E2=80=93 This method requires V-Ray. It produces the same result as t= he default Volumetric option by using p= rocedural geometry made up from multiple transparent layers. Used when= rendering Fire/Smoke for exporting deep images and Render Elements such as= Normals, Velocity, Multi Matte, etc. which would not be available in = default Volumetric mode. Note that enab= ling this option would slow down rendering.
Approximate and Approximate+Shadows
Motion Blur Mult. | mbmult=
em> =E2=80=93 Specifies a multiplier that affects the strength o=
f the motion blur. This value can be a negative number. =
p>
Volumetric Motion Blur | vol_moblur_metho=
d =E2=80=93 Specifies the type of Motion Blur that will be used.<=
/p>
Ray-traced =
=E2=80=93 The default Volumetric Motion Blur method. Note that the Grid-based method only affe=
cts the Volumetric, Volumetric Geometry, and Volumetric Heat Haze Modes and=
it doesn't apply to Mesh, Ocean Mesh, Cap Mesh, or Isosurface Modes.
Displacement is a technique intended to a= dd detail to the simulation during the rendering. The idea of the Phoenix d= isplacement is similar to the usual geometry displacement: a texture is sam= pled, and the corresponding point of the fluid volume or surface is shifted= in a direction at a distance determined by the texture. You can plug any V= -Ray, 3ds Max or Phoenix texture maps.
Enable | displacement, disp= lmul =E2=80=93 Enables the displacement effect, and enables the u= se of a multiplier value to increase or decrease the overall displacement e= ffect.
The difference between Surface= driven and Vector displacement is that = vector displacement can produce more complicated surfaces. For example, a w= ave texture in Vector mode produces waves that have = a convex back side and a concave front side, in contrast with the symmetric= al forms produced by Surface driven displacement.
Type | displ2d =E2=80=93 Specif= ies the displacement method that will be used.
Gradient driven =E2=
=80=93 Requires a monochrome texture map. The displacement amount is t=
he texture's brightness at each point. Each point of the fluid is shif=
ted along the gradient of the Surface channel. This =
means that each point in space could have a different displacement directio=
n. This method is suitable for smoke and fire.
Surface driven =E2=80=93 Requires a monochrome texture map. The displacem=
ent amount is the texture's brightness at each point. Each point of th=
e fluid is shifted along the normal of the point's projection on the i=
sosurface of the fluid's Surface channel. The t=
exture is also sampled at the projection point. Unlike the Gradient driven displacement, this ensures that all points abo=
ve or below the fluid surface will be displaced in the same direction, and =
so displacing fire/smoke simulations produces better results that are more =
similar to displaced solid geometry surfaces. However, the Surfa=
ce driven method is slower than Gradient driven.
Vector =E2=80=93 Requires a colored vector tex=
ture map (with negative and positive values). The point is shifted by =
the texture color, interpreted as a 3D vector. This displacement mode =
is intended to be used with the Phoenix FD Ocean Texture but can be used with any other vecto=
r displacement texture.
Advection =E2=80=93= Requires a colored 0.0-based vector texture map (with negative and positiv= e values). A very similar method to Vector, but does not = produce grainy structures for fire and smoke. Can be combined with the Phoe= nix Grid Texture, with i= ts Channel set to Velocity, to pro= duce render-time gridless advection.
Map | displ2 =E2=80=93 Specifies = the displacement map. Depending on the Type option s= elected, a monochrome map or a color map could be required. If a colored ma= p is specified when a monochrome map is needed, the strength of the displac= ement is determined by the total intensity of the color. If a monochrome ma= p is specified when a vector map is needed, the entire displacement will po= int in a single direction. For more information on texture mapping in Phoen= ix, please check the T= exture mapping, moving textures with fire/smoke/liquid, and TexUVW page= .
Surface Grid Channel | sarg =E2= =80=93 Specifies the channel that will define the surface of the flui= d used for the displacement.
Texture - the value=
s of a custom texture will define the mesh surface. You can see how this wo=
rks in =
this How-to video.
Temperature - Temperature c=
hannel will define the fluid surface. Temperature is typically in the range=
600-2000 for Fire/Smoke simulations.
Smoke - the =
Smoke channel will define the fluid surface. Smoke is typically in the rang=
e of 0-1 for Fire/Smoke simulations.
Speed - the&n=
bsp;Speed channel will define the fluid surface. Speed channel output has t=
o be enabled for this to work. Speed is calculated as the length of the vel=
ocity vector for each voxel.
Fuel - th=
e Fuel channel will define the fluid surface. Fuel channel output has to be=
enabled for this to work.
Texture | stex =E2=80=93 If the= Surface channel is set to Texture, this slot specifies the texture. For more information on texture mapp= ing in Phoenix, please check the Texture mapping, moving textures with fire/smoke/liquid, and T= exUVW page.
Isosurface Level | surflevel&n= bsp;=E2=80=93 Allows you to specify a threshold value for the generati= on of the geometry surface. Grid cells below this value will be ignored.
Render Presets... =E2=80=93 Opens a m= enu for loading and saving different presets. The following options are ava= ilable: