2.4. Effects
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## 2.4. Effects

### 2.4.1. Glow

### Chris Huff

This atmospheric glow effect makes a fast-rendering glow effect. It is based on the light source glow effect from POV-AFX, written by Marcos Fajardo, but has been heavily modified.

Syntax is:

    glow {
      type 0 | 1 | 2 | 3
      location VECTOR
      size FLOAT
      radius FLOAT
      fade_power FLOAT
      color COLOR
      TRANSFORMATIONS
    }

You can specify glows individually, or attached to a light_source. If created in a light source, they will be automatically initialized with the light's position and color (though transforming the light source will not give the expected result).

Choose a glow `type` from 0, 1, 2 or 3. Type 2 and 3 glows are not completely implemented yet, but 2 will be based on the exp() function and 3 will simulate a sphere with constant density.

The `size` keyword adjusts the scale of the glow effect. It is not an absolute size, just a scaling amount (because some glows are infinite). It does not quite work properly yet, it causes strange effects with changing distances of objects behind the glow.

The `radius` keyword specifies a clipping radius confining the glow to a circular area perpendicular to the ray. If the glow is still visible at this radius, it will make a sudden transition.

The `fade_power` keyword allows you to provide an exponent to adjust the falloff with.

| Note
A glow is not an object, it is an atmospheric effect. Therefore glows cannot be used in CSG operations. Transformations on a glow only affect the `location` vector. So will `scale` not change the size or shape of a glow, but scale the location coordinates.

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2.3. Objects | Home | 2.5. Textures and patterns