So intuitively this should be the angle between the surface normal and the direction the camera is facing, right? I would have thought it would output a linear range of values from 0° to 90° normalized to range from 0 to 1. This would be usefull. However… if that was the case if we took a color ramp node and divided it into 9 separate equal parts and then fed the output at 0.5 value as Layer Weight node’s Blend property we should get a different color every 10 degrees, correct? But it is not the case:
So what is it that Facing output is supposed to represent? Does anyone have any thoughts? Am I missing something?
I have just measured some values from a colour ramp based on the facing node. I created a cylinder with 36 faces - viewed head on and applied a linear colour ramp.
This is how the values change with angle based on the setting of the Facing value
Although not linear - a setting of around 0.75 appears to give the most linear response in this graph (i.e. a 45 degree angle corresponds to the colour in the centre of the colour ramp).
Maybe it’s like the roughness setting in the new Principled shader - in that you need to take the square root. So if you want an exact 50:50 split in the colour ramp - you need to take the square root of the half way point (i.e. 0.5). This would correspond to a Facing value of 0.707.
Yeah. So still what is Facing value range supposed to represent? It’s not linear. Yes it does what it says. 0 is one, 1 is another, what is inbetween is what interests me.
“The formula is IOR = 1/(1 - blend) – brecht May 1 '15 at 9:31” What IOR? Layer weight assumes some random IOR value is it 1.45? Is it just me, or is this not making a whole lot of sense in terms of a usable intuitive value?
OK, so Facing seems to be the same as inverted dot product of incoming and normal. Incoming and normal vectors are normalised so is that cos of the angle?
I just think that having the Facing values as a range of angles would be far more intuitive to work with when making effects such as custom fresnel curve with nodes (it’s too subtle of an effect to make a difference, but still) or to use it to achieve effects like micro roughness. That’s why I am interested in what the values represent numerically. I would like to convert Facing output to a linear range of angles, however as far it seems it is unclear what the current values are supposed to be.
So still what is Facing value range supposed to represent? It’s not linear. Yes it does what it says. 0 is one, 1 is another, what is inbetween is what interests me.