Processing 1.0 - Processing Discourse - How to create a perfect circle/ellipse ?

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Index › Programming Questions & Help › Syntax Questions › How to create a perfect circle/ellipse

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How to create a perfect circle/ellipse ? (Read 4782 times)

andrewowaun Full Member Offline Posts: 202 Barbados	How to create a perfect circle/ellipse ? Dec 19^th, 2009, 1:22pm I want to create a perfect circle without any anti-aliasing or jaggies. Is this possible with processing?

blindfish God Member Offline Posts: 793	Re: How to create a perfect circle/ellipse ? Reply #1 - Dec 19^th, 2009, 3:03pm You may need to be more specific about your needs. Presumably you want more than just ellipse
	Where is the what if the what is in why?

PhiLho YaBB Moderator Offline Posts: 4190 Near Paris (France)	Re: How to create a perfect circle/ellipse ? Reply #2 - Dec 20^th, 2009, 1:09am Also look at smooth().

JR Full Member Offline Posts: 149	Re: How to create a perfect circle/ellipse ? Reply #3 - Dec 20^th, 2009, 2:29am ... and you probably mean "without any aliasing". Anti-aliasing is what you do to get rid of that.

andrewowaun

Re: How to create a perfect circle/ellipse ?
Reply #4 - Dec 20^th, 2009, 3:28am

JR wrote on Dec 20^th, 2009, 2:29am:

... and you probably mean "without any aliasing".

Anti-aliasing is what you do to get rid of that.

That's exactly what I mean. The closest I have come to it, is using P2D or JAVA2D as the renderer, but even with smooth() or hint(ENABLE_OPENGL_4X_SMOOTH() there is anti-aliasing.

What i am looking to achieve is the perfect circle tracing the exterior of a compact disc or DVD would create. That pixel perfection.

I may have to create a large sketch, create the circle and then scale back down; but in my mind that would still result in the software-anti-aliasing which I don't want.

jaylfk

Re: How to create a perfect circle/ellipse ?
Reply #5 - Dec 20^th, 2009, 5:18am

andrewowaun wrote on Dec 19^th, 2009, 1:22pm:

I want to create a perfect circle without any anti-aliasing or jaggies.

Is this possible with processing

Without anti-aliasing you can't get a perfect circle.
It is dependent on your display's dot pitch.
http://en.wikipedia.org/wiki/Dot_pitch

Code:


void setup(){
  size(300,300,JAVA2D);
  smooth();
  ellipseMode(CENTER);
}

void draw(){
  background(0);
  ellipse(width/2,height/2,250,250);
}

« Last Edit: Dec 20^th, 2009, 9:12am by jaylfk »

PhiLho

Re: How to create a perfect circle/ellipse ?
Reply #6 - Dec 20^th, 2009, 11:34pm

andrewowaun wrote on Dec 20^th, 2009, 3:28am:

there is anti-aliasing.

To be clear (correct vocabulary is important in Internet technical communication

):
JR rightfully corrects you (I haven't caught the mistake): if you draw in binary colors (eg. pure black & white), you get a stairs effect on diagonal lines, ie. you see each pixel distinctly, jagged, with saw teeth...
It is called "aliasing".
To avoid this, computer people put half-tone pixels between the pure pixels, blurring a bit the line but making it smoother.
It is called "anti-aliasing".

blindfish

Re: How to create a perfect circle/ellipse ?
Reply #7 - Dec 21^st, 2009, 3:50am

andrewowaun wrote on Dec 20^th, 2009, 3:28am:

I may have to create a large sketch, create the circle and then scale back down; but in my mind that would still result in the software-anti-aliasing which I don't want.

If this is intended for print you'll definitely need to create a larger sketch. Good quality print resolution is around 300dpi (though you can get away with lower); and whilst people often mistakenly suggest monitors run at 72dpi it's certainly correct that they have a much lower resolution than print: so what might look good on screen may still look aliased (i.e. jaggy) in print.

If you aim for 300dpi then it's simply a matter of knowing the dimensions of your printed output in inches and multiplying by 300 to get the pixel dimensions... It's likely to be big, but if its for print you'll be doing individual renders rather than looping in draw Wink

Where is the what if the what is in why?

subpixel

Re: How to create a perfect circle/ellipse ?
Reply #8 - Dec 23^rd, 2009, 7:51am

andrewowaun wrote on Dec 19^th, 2009, 1:22pm:

I want to create a perfect circle without any anti-aliasing or jaggies.

Is this possible with processing

A perfect circle is a purely hypothetical construct. If you look close enough, a real DVD has bumpy edges (look closer still and you might find what you thought were edges aren't even there!..)

Quote:

I may have to create a large sketch, create the circle and then scale back down; but in my mind that would still result in the software-anti-aliasing which I don't want.

You need to say what you do want, then, since it seems you have asked for a program (software) to produce an anti-aliased image, but you are also saying you don't want software anti-aliasing.

If it is for print, consider producing a PDF or some other vector output format which the target device can render at whatever resolution it likes.

-spxl

Processing: subpixels.com, OpenProcessing.org | VJ portfolio: SPXL.TV

blindfish

Re: How to create a perfect circle/ellipse ?
Reply #9 - Dec 23^rd, 2009, 8:04am

A PDF will certainly make it simpler to deliver the image to the printer but it is not by definition vector-based: you can quite easily insert a low resolution raster image into a PDF that will look dreadful in print. Saying that I've no idea how Processing generates PDFs, so maybe they are always vector based?

Where is the what if the what is in why?

subpixel

Re: How to create a perfect circle/ellipse ?
Reply #10 - Dec 24^th, 2009, 6:43am

*rolls eyes*

If it is for print, consider producing a PDF (or some other vector-capable format) with vector objects which the target device can render at whatever resolution it likes.

By "vector" I mean non-bitmapped, as in capable of representing mathematical curves, line segments, and other geometric constructs.

Processing: subpixels.com, OpenProcessing.org | VJ portfolio: SPXL.TV

blindfish God Member Offline Posts: 793	Re: How to create a perfect circle/ellipse ? Reply #11 - Dec 24^th, 2009, 7:20am Sorry - maybe that was a little pedantic of me; but it is worth making our replies idiot-proof, just in case
	Where is the what if the what is in why?

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