How to draw an arc?

[prototypez]

This question has probably been asked a thousand times, but what is the best way to draw an arc? I don't see a standard method for drawing one on the module wiki, so I thought I might ask here...

[TechnoCat]

If it is an arc as part of a circle. Using scissor with circle will do just fine.
http://love2d.org/wiki/love.graphics.setScissor
http://love2d.org/wiki/love.graphics.circle

[Robin]

If it is an arc as part of a circle. Using scissor with circle will do just fine.
http://love2d.org/wiki/love.graphics.setScissor
http://love2d.org/wiki/love.graphics.circle

Oh, that's a good idea! I usually build a polygon with cos and sin and then draw that.

[zac352]

What about bezier curves? You can't really use circles for that.

Here's a simple non-linear equation drawing example:

Code: Select all

function f(x) --Squirrel ftw. :O local f=@(x) x^2+2*x+3
return x^2 + 2*x + 3 --Edit: I forgot that Lua nor Squirrel do "2x". 2*x, yes.
end
for i=1,1000 do
love.graphics.line(i-1,f(i-1),i,f(i))
end

[prototypez]

Thank you for the tips! They help out a lot. This place really is too friendly...

[Ryne]

Thank you for the tips! They help out a lot. This place really is too friendly...

Dude, were called the "LÖVE" forums. Of course we're friendly.

[TechnoCat]

Welcome to Costco. I love you.

[prototypez]

So, I actually got off my lazy bottom(okay, sat on my lazy bottom) and wrote out a arc-drawing module... I'm posting it in it's rather fragile and unstable form for comments, as this is my first public bit of LOVE programming... I used quads to interpolate arcs that can be either like a pie chart or like a true arc. Next additions will be elliptical arcs.

Usage is as follows:

arcchart = org.theflameimperishable.love.ArcChart({

x = --center of chart--,
y = --center of chart--,
innerradius = --radius of inner circle--,
outerradius = --outside radius--,
segments = --requested number of segments--

})

Draw in the love.draw() cycle with:

arcchart:drawSegments(startsegment, endsegment) -- for particular segments
arcchart:drawDegrees(startdegrees, enddegrees) -- for arc in degrees(yeah yeah, I'm not a math major so I don't like rads, don't yell at me!)

Also, just calling arcchart:draw() draws the stored segment dictated by member variables arcchart.startsegment and arcchart.endsegment, and these can be either set directly(gritting teeth because field hiding has been ingrained in me since the Java days...) or calling arcchart:increment(), arcchart:decrement(), and arcchart:reset(), all of which accept values as well.

I'd be interested in comments if anybody needs such a thing. Also, as it uses quads, I used lookup tables for all of the values, but this can be turned off if the arcs need to be zoomed or moved dynamically, just set the precomputed bool value in the object to false. I haven't seen a huge performance difference between the two, any ideas about that out there?

[Robin]

org.theflameimperishable.love.ArcChart

Where does that come from? Java?

(gritting teeth because field hiding has been ingrained in me since the Java days...)

OMG, I was right!

But anyway, I should definitely take a look at it. This should be some useful shit.

[kikito]

Code: Select all

if (not org) then
	org = {}
end
if (not org.theflameimperishable) then
	org["theflameimperishable"] = {}
end
if (not org.theflameimperishable.love) then
	org.theflameimperishable["love"] = {}
end

org.theflameimperishable.love["ArcChart"] = {}

--Begin ArcChart namespace

do

You could do the same like this:

Code: Select all

 org = org or {}
org.theflameimperisable = org.theflameimperisable or {}
org.theflameimperishable.love = org.theflameimperishable.love or {}
org.theflameimperishable.love.ArchChart = org.theflameimperishable.love.ArchChart or {}

do
...

Or you could use the built-in module function in two lines:

Code: Select all

module('org.theflameimperishable.love.ArchChart', package.seeall) -- creates the tables automatically
-- everything declared from here on is inside the org.theflameimperishable.love.ArchChart module.

Some people don't like that though.

(gritting teeth because field hiding has been ingrained in me since the Java days...)

I'm so sorry for you.

Learning Ruby on Rails will purify you, given enough time.