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Author Topic: sf::vertexarray to make circles  (Read 8195 times)

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ansh93

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sf::vertexarray to make circles
« on: November 15, 2014, 11:45:54 am »
I want to make circle using vertex arrays, how can I do that ?

I only want to be able to see the outline of the circle, I dont want a circle filled with a color, cuz I want to use it for debug drawing.
Help !!

eXpl0it3r

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Re: sf::vertexarray to make circles
« Reply #1 on: November 15, 2014, 11:57:47 am »
What about spending 10 secs looking through the official tutorials before asking?

http://sfml-dev.org/tutorials/2.1/graphics-shape.php
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ansh93

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Re: sf::vertexarray to make circles
« Reply #2 on: November 15, 2014, 12:00:07 pm »
What about reading the whole question before replying ?
I said I want to create circle using vertex array, not using sf::CircleShape
« Last Edit: November 15, 2014, 12:02:20 pm by ansh93 »

Nexus

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Re: sf::vertexarray to make circles
« Reply #3 on: November 15, 2014, 12:01:59 pm »
You approximate a circle with a polygon of many points. The points have the following positions:
center.x + radius * cos(angle)
center.y + radius * sin(angle)
angle is increased stepwise, so it's uniformly distributed in [0, 2*pi[.

Alternatively, you could use thor::PolarVector2f.
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eXpl0it3r

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Re: sf::vertexarray to make circles
« Reply #4 on: November 15, 2014, 12:16:29 pm »
You could always set the outline color and a transparent fill color for a shape.

If you otherwise want to use something "lower level" you might just have to learn the math behind it, as Nexus pointed out.
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ansh93

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Re: sf::vertexarray to make circles
« Reply #5 on: November 15, 2014, 12:27:56 pm »
Cool I got the circle made up using the above method
Thanks  :D

Hapax

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Re: sf::vertexarray to make circles
« Reply #6 on: November 16, 2014, 02:18:20 am »
It's good that you got the vertex array working to make the circle as you wanted but, since you're only using it for "debugging" (assuming something like showing position feedback visually), you may way to look at what eXpl0it3r was talking about. CircleShapes can be much quicker and easier to set up than vertex arrays and they can easily draw rings (circle outlines with no fill).
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ansh93

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Re: sf::vertexarray to make circles
« Reply #7 on: November 16, 2014, 09:41:53 am »
It's good that you got the vertex array working to make the circle as you wanted but, since you're only using it for "debugging" (assuming something like showing position feedback visually), you may way to look at what eXpl0it3r was talking about. CircleShapes can be much quicker and easier to set up than vertex arrays and they can easily draw rings (circle outlines with no fill).

Yup right, thats what my debug draw does, it just shows the collision boxes of all the objects.
I know sf::CircleShape method already, but I dont want to do it that way thats why I specifically for how to do them with vertex arrays.

Hiura

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Re: sf::vertexarray to make circles
« Reply #8 on: November 16, 2014, 01:46:38 pm »
A few years ago I wrote this tools: https://github.com/mantognini/sftools/blob/develop/include/sftools/Curve.hpp It can display arbitrary curves with custom color/thickness. In case that helps you..
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