Drawing Arcs / Circular sectors

[farnoy]

Hi,

How to draw a http://en.wikipedia.org/wiki/Circular_sector using generic SFML shape? I haven't seen any Arc functions in Shape class and drawing lines also doesn't cover angles.

[pdinklag]

You can't technically render arcs or perfect circles, you split your arc / circle / sector up into as many triangles or straight lines as you require to get your desired level of detail.

For a perfect circle and circular sectors <= 180 degrees, a convex n-gon portion will work, but circular sectors with an angle between 180 and 360 degrees could only be represented by a concave polygon, which is why you'll probably have to go the multi-triangle way.

[farnoy]

Thanks for your response.

What do you think about finding points by this equation:  http://en.wikipedia.org/wiki/Circle#Cartesian_coordinates

Code: [Select]

x = a + r cos(t)
y = b + r sin(t)


Wouldn't this give me a good level of detail?

[OniLinkPlus]

Thanks for your response.

What do you think about finding points by this equation:  http://en.wikipedia.org/wiki/Circle#Cartesian_coordinates

Code: [Select]

x = a + r cos(t)
y = b + r sin(t)


Wouldn't this give me a good level of detail?

That's the exact equation you need to use.

[Nexus]

By the way, in case you use Thor, there is a Shapes::Pie() function that creates circular sectors.

You can't use a single sf::Shape reliably, since the sector may be concave and sf::Shape only supports convex shapes. That's why the Pie() function returns thor::ConcaveShape instead.