arc

nitta

I wrote this one.

function draw() { arc(50,55,60,60,PI,PI); }

I thought nothing would appear. but It appears half circle like this.

I understand arc(x,y,width,height,start,stop);

Why start and stop are the same arguments but half circle appears?

Chrisir

Or is start and then how long the angle is?

jeremydouglass

@nitta --

That is strange. In Processing (Java) start and stop are absolute, and this is what would generate the image you share:

arc(50, 55, 60, 60, PI, TWO_PI);

I'm not sure whether the arc stop argument is instead relative in p5.js -- that would be a surprising difference, and might be a bug.

Are you setting ellipseMode() in your sketch?

• https://p5js.org/reference/#/p5/arc
• https://processing.org/reference/arc_.html

Draws an arc to the screen. Arcs are drawn along the outer edge of an ellipse defined by the a, b, c, and d parameters. The origin of the arc's ellipse may be changed with the ellipseMode() function. Use the start and stop parameters to specify the angles (in radians) at which to draw the arc.

GoToLoop

https://GitHub.com/processing/p5.js/issues/740#issuecomment-113974932

nitta

Thank you all. but now Im more confused. I tried more patterns below. 0 to 90 degree is circle appear. 91 to 270 degree is half circle appear. 271 to 350 is nothing wold appear. 351 to 360 circle appear.

Lord_of_the_Galaxy

Very strange indeed.

jeremydouglass

@nitta -- would you submit an issue to p5.js issues?

• https://github.com/processing/p5.js/issues

Before doing so, you mightalso want to consult this closed issue -- apparently p5.js chose to implement arc differently from Processing in ways that may explain some of your edge cases:

• https://github.com/processing/p5.js/issues/902