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Clarify and simplify formula for attenuation #2414

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Jun 19, 2024
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Clarify and simplify formula for attenuation #2414

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10 changes: 7 additions & 3 deletions extensions/2.0/Khronos/KHR_materials_volume/README.md
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Expand Up @@ -157,11 +157,15 @@ T(*x*) = e<sup>-σ<sub>t</sub>*x*</sup>

where T is commonly referred to as *transmittance*.

Substituting σ<sub>t</sub> in the previous equation by its definition via *attenuation color* and *attenuation distance*, as defined above, and setting *x* = *d* we get
Substituting σ<sub>t</sub> in the previous equation by its definition via *attenuation color* and *attenuation distance*, as defined above, we get

T(d<sub>a</sub>) = e<sup>(log(*c*) / *d*) * *d*</sup> = *c*
T(x) = e<sup>(log(*c*) / *d*) * *x*</sup>

So, after traveling distance *d* through the medium we get attenuation color *c*.
The above formula can be simplified as:

T(x) = *c*<sup> *x* / *d*</sup>

So, after traveling distance *x* through a medium with attenuation color *c* and attenuation distance *d*, we get we get transmittance T(x).

## Base Color and Absorption

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