Chapter 7

Chapter 7 A little taste of using the arc confusion

#1 elpuerco63

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Posted 04 July 2012 - 01:05 PM

The description on this page (316) seems to contradict itself between using positive degrees and negative degrees dependant on direction, am I right?

In one part to quotes positive degrees when according to the details it should be negative?

#2 Beth Robson

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Posted 04 July 2012 - 04:29 PM

It's *very* easy to get confused with the directions and angles in creating an arc. I have been confused on this so many times before I finally got it!

In the example, we are measuring the angle using clockwise measurement. But the arc we're drawing is drawn counter-clockwise!

To measure the degrees when going clockwise, you use positive degrees. That's why we use 270, not -270 or 90.

Don't mix up the direction in which you measure the angle, and the direction you're tracing the arc. Two different things!

Can you point out more specifically where we might have messed it up? I am not seeing it.

Thanks,

Elisabeth

Elisabeth Robson
Co-founder, WickedlySmart.com
Author: Head First HTML5 Programming, Head First HTML and CSS, Head First Design Patterns

#3 elpuerco63

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Posted 04 July 2012 - 10:47 PM

Hi, first off thanks for speedy response!

After a good night sleep, reading your explanation here and then revisiting the page in question I can see it makes sense as you describe!

Sorry I lost sight of direction of arc.....even though it is stated in black and white!....doh!

Thanks, and thanks for an awesome book! Can't wait for the HTML & CSS book to come out in September ;-)