Smoke Fade Shader

The smoke fade shader addresses a very specific but surprisingly common need: a smoke or steam effect, usually animated with a video texture, that can appear to be emitting from a hose or grating. Placing a rendered video card with a steam or smoke texture into the surface will have a hard edge.

The smoke fade shader defines a ground plane into which the texture is faded, looking like its appearing just above the surface.


The controls (in Maya):



The shader is intended for flat cards placed in the scene, with smoke texture or movie on it.

The alpha channel for the card can come from one of three sources:

  • Static alpha channel in the color texture itself
  • A separate alpha channel texture (typically for video textures)
  • Generated using a “clip level” value from the brightness of the color texture

Either of the two boxes “Use AlphaSampler” and “Alpha Clipmap/Stencil mode” can be checked to enable the options. When neither is selected the alpha channel of the color texture will be used (if present, if not the texture will be solid).

When the AlphaSampler is selected the Alpha Channel option indicates which of its color channels to use for transparency: 1=red, 2=green, 3=blue, 4=alpha (if present).

When “Alpha Clipmap/Stencil mode” is selected transparency is generated from the Alpha Clip Level value.

Floor height indicates the height at which the smoke fades to nothing. Decay distance indicates the distance over which the fading will occur

Smoke intensity helps adjust brightness.


Download the Shader Library 2014 package from the Dashboard.