Facing Ratio

Tinted car paint effect using facing_ratio (rollover image)


This shader returns the absolute value of the dot product between the shading normal and the incoming ray direction. It is also named Incidence in other renderers. Unlike the utility shader used in ndoteye mode, facing_ratio works for any type of ray, not just camera rays. The returned values are always in the [0..1] range.

A tutorial that shows how to use the Facing Ratio to create a toon shader can be found here.

'Heat map' effect using a facing_ratio -> v_coord of ramp




Push or pull values by altering the slope at the beginning of the range. Bias values below 0.5 decreases the slope and lower values overall.  Above 0.5, the slope is higher, and the value grows more quickly. A value of 0.5 has no effect.


Increase or decrease the slope of the mid-range values. Gain values below 0.5 increase the contrast whereas values above 0.5 flatten the mid-range values. A value of 0.5 has no effect.


When enabled, the facing_ratio shader will output a linear, normalized angle instead of N·Eye. 


Return the complement of the result (1 - x).



facing_ratio connected to opacity of standard_surface shader




Pepe model by Daniel M. Lara (Pepeland)

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