Hi,

I was hoping someone might be able to clarify what the value range is of the @Cd attribute.

The docs say it is a vector of 3 floats but I haven't been able to find what the actual range is.

My understanding was that each float in the vector representing the respective RBG values would be from 0-1.

However in experimenting with values it seems that the actual range is from 0 to 2.55 ;

Representing a scaled representation of 0 to 255.

The reason I say that because ( in the file attacted in which I test the different red values of the first float of the vector ) I can see a change in the brightness of say setting the red value to 2.01 then changing it 2.55.

The span of change ( for my eyes at least ) needs to be about that of 0.4 difference, and I can see differences in color for any change less than 2.55

If I set it to 2.55 then change it to 6.0, I see no change which is why I'm led to believe the range is 0 to 2.55 and not 0 to 1.

Can anyone concur or am I misunderstanding whats going on?

Thanks

Upper bound appears to be @Cd = 1e38
Lower bound appears to be @Cd = 1e-45

The viewport display 0-1 range only, turn on HDR Rendering too, in Display options/Effects

Forgive my lack of math notation.

When you say 1e38 your meaning the hex value? and not exponent value of one? such that 1 times itself 38 times? which if it was only gives 1 anyways.

And in the viewport if the display is only for 0-1 how come I can see differences say between 1.8 and 2.5 or even 1 and 1.9?

And yes for all my testing so far I have had HDR set as you say.

Thanks.

https://en.wikipedia.org/wiki/Scientific_notation [en.wikipedia.org]
1e38 = 100,000,000,000,000,000,000,000,000,000,000,000,000

BabaJ
And in the viewport if the display is only for 0-1 how come I can see differences say between 1.8 and 2.5 or even 1 and 1.9?

You ‘default diffuse’ in Display Option/Effects is probably not set to one.

Thanks for the ‘math’ lesson Arctor…I should have known that…geesh.

So my diffuse was set to 0.4 for all 3 values and I changed it to 1 for all 3 and turned off specular, ambient and emission.

But I still can see differences between say 1, 1.5 and 3

But it's ok, it doesn't matter…starting to see something important to keep in mind as I build my vex functions.

With such a big range possible for values ( 1e38, 1e-45 ) and seeing how what I end up actually getting; It depends on where I actually end up having those values “piped” too.

In one case with Artyes' feedback he's showing me there's some viewport settings that determine the end result.

And I guess when I get to the part of working out shaders/lighting for my vex created objects I am going to have to give similar considerations; How those color values will be “interpreted”.

So once I work through that I'll have to work out how I want to setup my color algorithm settings for patterns within the vex code I'm writting.

Thanks guys for your usefull feedback.

BabaJ
But I still can see differences between say 1, 1.5 and 3

Make sure to ‘disable lighting’ too. light bulb with x in it, right side of toolbar.

Yeah…disabled lighting too…

..and still can see a difference between 1 and 6.

I looked around for other possibilites like I tried setting gamma to 0…and also tried switching out scene viewports ( create new, close old ).

it's ok though…although you've got me interested in why…lol

Unless you have viewport colour correct then I can't reproduce that one.