How to change alpha without changing the whole color?

notalentgeek

Hello I was wondering how can I change the opacity of a color object without re writing the color back. Is this a possibility? Like color(255, 255, 255).alpha(100) or something similar?

Just a side question, how can you search for documentation in the Processing API here http://processing.github.io/processing-javadocs/core/? I want to search for Color class but have no luck :(.

GoToLoop

There's no Color class in Processing's API. color is the same as Java's primitive type int:
https://Processing.org/reference/color_datatype.html

When we pass 3 arguments to functions color(), fill() and stroke(), it's assumed it's a 100% opaque color.
If you want to specify another alpha value besides 255, just pass it as their 4th argument:
https://Processing.org/reference/color_.html

notalentgeek

Is there a way so that I can change alpha without re inputting the argument 1 to argument 3?

GoToLoop

noLoop();
final color redColor = color(255, 0, 0);
final color alphaColor = 100 << 030;
fill(redColor & ~#000000 | alphaColor);
ellipse(width>>1, height>>1, width>>1, height>>1);

notalentgeek

Works great thanks!