error with color epxression

[Dan Ebberts]

I think it should be like this:

var red=thisComp.layer(“Controls”).effect(“Red”)(“Slider”);
var green=thisComp.layer(“Controls”).effect(“Green”)(“Slider”);
var blue=thisComp.layer(“Controls”).effect(“Blue”)(“Slider”);
var alpha=1;

var hsl = rgbToHsl([red,green,blue,alpha]);
hsl[0]+=.5;
if (hsl[0]>1)hsl[0] -= 1;
var rgb = hslToRgb(hsl);
rgb

Dan

[Assaf Goldlust]

wait, so why in the book its looks like this?

[Dan Ebberts]

It definitely does not look like that in my copy. Maybe you have a newer edition, where it somehow got messed up.

Dan

[Assaf Goldlust]

Well,this sucks

[Assaf Goldlust]

Any way, i have another queation.
At some point in the expression he used the code

hsl[0] + = .5;

And later he explained:
“+ = .5” means add .5 to whatever the value already is.

Im slightly confused,
What is tge diffrence bewtween the usual
Value=+.5?

[Dan Ebberts]

It would be:

hsl[0] += .5;

(no space between the + and the = ).

+= is a JavaScript shorthand operator that gives you the same result as:

hsl[0] = hsl[0] + .5;

Dan

[Assaf Goldlust]

So if i lets say want to do:
T=transform.position[0]+5;

I can instead do?
transform.position[0]+=5;

[Dan Ebberts]

The first one takes the layer’s x postion, adds 5 to it, and stuffs the result in variable T.

I don’t think the second one actually does anything (except maybe generate an error). So no, they’re not equivalent.

Dan

[Assaf Goldlust]

so whats is this operator function?

i mean in general not just in the contest of this color expression?

[Dan Ebberts]

+= is one of JavaScript’s assignment operators.

Where

x += y

is the same as

x = x + y

Dan