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A Constant Fog

The simplest fog type is the constant fog that has a constant density in all locations. It is specified by a distance keyword which actually describes the fog's density and a fog color.

The distance value determines the distance at which 36.8% of the background are still visible (for a more detailed explanation of how the fog is calculated read the reference section "Fog").

The fog color can be used to create anything from a pure white to a red, blood-colored fog. You can also use a black fog to simulate the effect of a limited range of vision.

The following example will show you how to add fog to a simple scene (fog1.pov).

  #include "colors.inc"

  camera {

    location  <0, 20, -100>

  }

  background { color SkyBlue }

  plane { y, -10

    pigment {

      checker color Yellow color Green

      scale 20

    }

  }

  sphere { <0, 25, 0>, 40

    pigment { Red }

    finish { phong 1.0 phong_size 20 }

  }

  sphere { <-100, 150, 200>,  20

    pigment { Green }

    finish { phong 1.0 phong_size 20 }

  }

  sphere { <100, 25, 100>, 30

    pigment { Blue }

    finish { phong 1.0 phong_size 20 }

  }

  light_source { <100, 120, 40> color White}

  fog {

    distance 150

    color rgb<0.3, 0.5, 0.2>

  }

According to their distance the spheres in this scene more or less vanish in the greenish fog we used, as does the checkerboard plane.

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