Sine waves color

[Marcola 6]

Hi,

I have a very basic question. I have a black and white sine wave function applied to a grid and i would like to change the color of each ring (black and white). How can i achieve that? 

Attached is the file i'm talking about.

Thanks!

VEX_SineWaves_ODF.hipnc

[Noobini 213]

not sure if I'm on the right track...is this what you want ?

vector pos = @P * chv("Position");
vector center = chv("Center");
float d = distance(vector(pos), center);
d *= ch('Scale');
@Cd = fit(sin(d - @Time*4), -1, 1, 0, 1);

if(@Cd.r>0.5){
    @Cd = set(1,1,1);
}
else{
    @Cd = set(0,0,0);
}

(it's crisper if you change your wrangle to run over prims)

Edited April 7 by Noobini

[Marcola 6]

Thanks for your reply Noobini. I also tried the if statement but as you can see the float fade color is lost when the if statement is applied. I keep getting a warning sign in Houdini stating that i should cast the line where the if sits. I tried casting it but i still couldn't get a smooth color as the original black and white rings, if that makes sense.

 

SideFX, would be very nice if you guys implement in H17 a better debugging system other than very basic error messages. People want to learn VEX and Houdini is awesome!

[Noobini 213]

i get NO warning. Are you sure you're using @Cd.r ? because that is a float....so it's correct to compare a float with 0.5.

If you use @Cd, that's a vector...so it's telling you to cast it properly (if you were comparing to a float)

(odd that if I use @Cd, I get the warning...correctly...but then if I scrub...the warning goes away, incorrectly !! Dunno...)

Edited April 7 by Noobini

[Marcola 6]

Ok, thanks for the info again. It makes sense. What i meant by saying "fade color" is a color transition that is not jagged, like the attached img.

I can change one ring color but not the second.

[Noobini 213]

add a Smooth but instead of working on P, work on Cd instead...also i think your @Cd.z = 255 is superfluous....1 is max I think.

[Marcola 6]

Alright, will try switching the P for Cd. The @Cd.z, in my mind, was because every value under 50 grey i wanted colored, as i used the fit function from 0 to 1. Probably, that is not the best approach for the problem but somewhat, it works. 

[Noobini 213]

there's also attribblur...I'm fooling around with it...not an expert with it tho...

[mestela 541]

http://www.tokeru.com/cgwiki/index.php?title=JoyOfVex13#Exercises

but more generally

http://www.tokeru.com/cgwiki/index.php?title=JoyOfVex

In your case you could do something like

float sin = fit(sin(d - @Time*4), -1, 1, 0, 1);
vector col_hi = chv('col_high');
vector col_lo = chv('col_lo');
@Cd = lerp(col_lo, col_hi, sin);

 

[Marcola 6]

Oh man! The master himself! Matt, thank you so much for the amazing material that you posted a few weeks ago in your website. Learning a lot with it! Some challenging exercises but i suppose that programming is supposed to make people think smart before implementing it. We should have a section in the odforce forum dedicated to the Joy of Vex. I bet that a lot of people have questions about the exercises.

 

Thanks for your help on my question. "Lerp" is a good friend. Cheers.