Processing 1.0 - Processing Discourse - how to increment color data

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how to increment color data (Read 1555 times)

vicente YaBB Newbies Offline Posts: 31	how to increment color data Aug 13^th, 2007, 6:47am I want to transform a color into other, but i don't know how to deal (increment or decrement) a color until a target. The data is in hexa? bits? where could i learn (very basic) some about that? I dont undestand shifiting or the (? : >>) stuff also . So how do i get started? thanks vk

Ira Full Member Offline Posts: 238 Dallas	Re: how to increment color data Reply #1 - Aug 13^th, 2007, 7:58am I cover it in Appendix B in http://friendsofed.com/book.html?isbn=159059617X Of course you could also google: bitwise operations
	Processing: Creative Coding and Computational Art http://friendsofed.com/book.html?isbn=159059617X The Essential Guide to Processing for Flash Developers http://www.friendsofed.com/book.html?isbn=9781430219798 Center of Creative Computation Meadows/Lyle SMU, Dallas

clickykbd YaBB Newbies Offline Posts: 24 Texas	Re: how to increment color data Reply #2 - Aug 13^th, 2007, 1:37pm Knowing the gory details of the bitwise stuff isn't entirely necessary. (I don't) You can use red() green() blue() and the other color representation conversion functions to go back and forth to values you can increment more intuitively. You'll suffer a performance hit no doubt. Incentive to learn the bitwise eventually.
	clicky [http://flickr.com/photos/clickykbd]

fry YaBB Moderator Offline Posts: 2623 mass, usa	Re: how to increment color data Reply #3 - Aug 13^th, 2007, 1:40pm the bitwise stuff is covered in the reference: http://processing.org/reference/leftshift.html http://processing.org/reference/rightshift.html or you can use lerpColor(): http://processing.org/reference/lerpColor_.html

vicente

Re: how to increment color data
Reply #4 - Aug 15^th, 2007, 3:39am

Thanks everybody for help.
I was using lerpColor already, but i'd like to try more control over the change.
I still like to understand the bitwise stuff (i know the name already, that's more than i knew). Can one add and subtract binaries numbers, how? And in hex.
How to change just one part of the number, for instance the Red portion?
shifting is just for multiply and divide?
I mean, more than the syntax, I'd like to find good texts about how to deal with this data.
thanks again.

clickykbd

Re: how to increment color data
Reply #5 - Aug 15^th, 2007, 4:21am

This seems to be one article for it many cite as a great reference:

Bitwise Operations in C
http://www.gamedev.net/reference/articles/article1563.asp

Examples are in C language, but should be pretty easy to map them to java/processing.

Just found this too, not extensive but Java.
http://www.particle.kth.se/~lindsey/JavaCourse/Book/Part1/Tech/Chapter10/bits.html

clicky [http://flickr.com/photos/clickykbd]

fry

Re: how to increment color data
Reply #6 - Aug 15^th, 2007, 11:06pm

vicente wrote on Aug 15^th, 2007, 3:39am:

Can one add and subtract binaries numbers, how And in hex.
How to change just one part of the number, for instance the Red portion
shifting is just for multiply and divide
I mean, more than the syntax, I'd like to find good texts about how to deal with this data.
thanks again.

again, read the reference links i posted. the second half of the examples (below the line) cover how to get the red, green, blue, and alpha components out, and then re-assemble them for other uses. you can't really manipulate a color directly by addition and subtraction--you have to break it into red/green/blue, change those values, and then assemble red/green/blue back into an int/color variable.

technically, bit shifting does multiplication and division, but it's not helpful to think about it that way with color data. just think about it as a way to pack and unpack colors into a int/color variable.

...or if you're really stuck, just use red(), green(), blue() and color().

vicente

Re: how to increment color data
Reply #7 - Aug 17^th, 2007, 7:23am

hummmmm. i see. Thanks Fry. Thanks clickykbd.
A little reading there, a little re-reading here and i start to get it.
So, argb >> 16 & 0xFF are two operations? I mean shifting 16 places and ANDing the shifted number with a mask ? This specifc mask (11111111) will always extract the lower part of the dword, right? This is why we shift the data before ANDing, ok so far? So we clear the whole dword but red information (in this case). Then the new dword (is it the correct name) when assigned to an int will give me the red value in decimal so i can work with it. right?
I will need to change the way things in my sketch were build so far to use this.

How much difference in performance should i get? Noticeable?
I'm doing big 2D arrays (like800*600) and changing each object to different color targets (using lerpColor so far).

fry

Re: how to increment color data
Reply #8 - Aug 17^th, 2007, 3:02pm

yes, that's correct. it's just an int, not a dword.. the reference should actually use parens:

int r = (c >> 24) & 0xff;

because & may bind later than >>, i can't recall offhand but will change it for the next rev.

the change in speed from using red(), green(), blue() etc will be significant. the change from using lerpColor() depends on how you're using it. internally, this is what lerpColor() does, you'd have to compare the source of PApplet.lerpColor from dev.processing.org against what you're doing to get an idea.

vicente YaBB Newbies Offline Posts: 31	Re: how to increment color data Reply #9 - Aug 17^th, 2007, 4:10pm thanks again. So every int is 32-bits?

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