Drawing a 90degree bend

[Yell0w]

How can i draw a 90 degree bend?
i have tried with arcs, but i only want the outer arc and not the lines leading to the center.
In the example i have covered over the part i dont want to show with a filled circle. Are there any simpler way to do this that i am missing?

Code: Select all

	love.graphics.setLine(4, "smooth")
	love.graphics.arc("line", 500, 400, 50, math.pi, math.pi/2 )
	love.graphics.arc("line", 400, 400, 50, math.pi, math.pi/2 )
	love.graphics.setColor(0,0,0)
 	emergencySolution = love.graphics.circle("fill", 500+2, 400-2, 50 )

[micha]

I haven't used the arc function before and actually I am surprised, it also draws the radii, when set to line mode. In my opinion (and obviously yours as well) it shouldn't do that.

Drawing a black circle on top does not solve the problem, because you don't know what color is behind.
Instead you can draw a bend by drawing many very small straight line segments. You can do this automatically(, in the sense that you don't need to enter all the coordinates by hand), but you need to write a function for that. Do you know how to use sine and cosine?

[bartbes]

In my opinion (and obviously yours as well) it shouldn't do that.

So you want to have two different definitions for the same arc?
Because if you want to stick with one, and you don't want those lines, then.. what does filled mean?
If you go with the current definition for filled, it only makes sense that when you ask for the outlines you.. get them..

[Nixola]

I think that not drawing the radii when in line mode is useful, because they're pretty easy to write on your own, while not drawing them is a bit trickier

[micha]

In my opinion (and obviously yours as well) it shouldn't do that.

So you want to have two different definitions for the same arc?

I don't understand what you mean by that. Could you please explain?

Because if you want to stick with one, and you don't want those lines, then.. what does filled mean?
If you go with the current definition for filled, it only makes sense that when you ask for the outlines you.. get them..

I agree, that when I use filled, I want to have a sector of a circle. The current implementation of the filled option is meaningful.

But also I agree with Nixola:

I think that not drawing the radii when in line mode is useful, because they're pretty easy to write on your own, while not drawing them is a bit trickier

This would be inconsistent, but user friendly, as the radii are easy to draw "by hand", while removing them is not.

And one last thing (I had to look it up myself, I am not a native speaker): The term arc refers to the one dimensional line object on the outside of a circle. See here: http://en.wikipedia.org/wiki/Arc_%28geometry%29. This is probably why I expected the "bend" only, without radii.

[kikito]

Well, the "line" function only has one "mode". Maybe there should be a "modeless" arc function that draws just the arc, and then the one with modes also draws the radii.

[Ref]

Other people separate the two options by using 'arc' or 'sector'.

[micha]

To get back to Yell0w's original question. I wrote a function for drawing arcs:

Code: Select all

function arcline(x,y,r,alpha1,alpha2,segment)
	-- Set number of segments, if not given
	segment = segment or math.floor(math.abs(alpha1-alpha2)*10)
	-- Calculate coordinates along the arc
	coordinates = {}
	for i = 0,segment do
		currentAngle = (i/segment)*(alpha2-alpha1)+alpha1
		coordinates[2*i+1] = x+math.cos(currentAngle)*r
		coordinates[2*i+2] = y+math.sin(currentAngle)*r
	end
	--draw everything
	love.graphics.line(coordinates)
end

Just call it like love.graphics.arc, only leave away the "line".
I put it in your program, see attachment.

[Yell0w]

Thats very elegant micha!. Maybe your function could be added as a parameter to the arc function in future releases?
Math is used alot in love and i wish i paid better attention at school