# OpenGL smooth line drawing using opengl

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Hi All, I am doing some graph drawing using opengl on windows 2k. I am facing problem releated to the drawing of the lines of the polygon. The drawing of the object is not smooth when i try to rotate the objects. The lines get distracted (becomes slight zigzag). I just wondering is there any API avaliable in opengl just to make these lines smooth? can any buddy has any clue about the same? Thanks in advance. -Kiran

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There's some things you can try to enable antialiasing without much hassle. From memory:

glEnable(GL_LINE_SMOOTH);
glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);

There's some other ways too, but this should get you started. Google "OpenGL Antialiasing" or something like that for more info.

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EDIT: Like ^he^ said...

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Hi ,
Actually i have tried following code to draw smooth lines.
glEnable (GL_POLYGON_SMOOTH);
glEnable (GL_BLEND);
glBlendFunc (GL_SRC_ALPHA_SATURATE, GL_ONE);
glHint (GL_POLYGON_SMOOTH_HINT, GL_NICEST);
glLineWidth (1.5f);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
but it did't worked.
so any other idea or clue for this.anyway thanks a lot for reply.
kiran.

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Quote:
 Original post by gadekar_kHi ,Actually i have tried following code to draw smooth lines. glEnable (GL_POLYGON_SMOOTH); glEnable (GL_BLEND); glBlendFunc (GL_SRC_ALPHA_SATURATE, GL_ONE); glHint (GL_POLYGON_SMOOTH_HINT, GL_NICEST); glLineWidth (1.5f); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);but it did't worked.so any other idea or clue for this.anyway thanks a lot for reply.kiran.

Replace GL_POLYGON_SMOOTH with GL_LINE_SMOOTH :)
And GL_POLYGON_SMOOTH_HINT with GL_LINE_SMOOTH_HINT :)

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Also, I'm not sure how a 1.5 line width affects the algorithms, it would seem that thicker lines might appear blockier (but this is just a wild guess way out there).

Other than that, there's always multisampling and such.

Check this page to get a higher-level overview of various antialiasing techniques available to you.

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