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POHow to render perfect wireframed rectangle in 2D mode with OpenGL?
 

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  1. POHow to render perfect wireframed rectangle in 2D mode with OpenGL?
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    <p><strong>Edit:</strong> just so you know: I have not solved this problem perfectly yet, currently I am using 0.5px offset, it <em>seems</em> to work, but as others have said, it is not the "proper" solution. So I am looking for the real deal, the diamond exit rule solution didn't work at all.</p> <p>I believe it is a bug in the graphics card perhaps, but if so, then any professional programmer should have their bullet-proof solutions for this, right?</p> <p><strong>Edit:</strong> I have now bought a new nvidia card (had ATI card before), and i still experience this problem. I also see the same bug in many, many games. So i guess it is impossible to fix in a clean way?</p> <p>Here is image of the bug:</p> <p><img src="https://i.stack.imgur.com/LBFXn.png" alt="enter image description here"></p> <p>How do you overcome this problem? Preferrably a non-shader solution, if possible. I tried to set offset for the first line when i drew 4 individual lines myself instead of using wireframe mode, but that didnt work out very well: if the rectangle size changed, it sometimes looked perfect rectangle, but sometimes even worse than before my fix.</p> <p>This is how i render the quad:</p> <pre><code>glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); glBegin(GL_QUADS); glVertex2f(...); glVertex2f(...); glVertex2f(...); glVertex2f(...); glEnd(); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); </code></pre> <p>Yes, I know I can use vertex arrays or VBO's, but that isn't the point here.</p> <p>I also tried <code>GL_LINE_LOOP</code>, but it didn't fix the bug.</p> <p><strong>Edit:</strong> One solution is at, which works so far: <a href="https://stackoverflow.com/questions/10040961/opengl-pixel-perfect-2d-drawing">Opengl pixel perfect 2D drawing</a> by Lie Ryan: </p> <blockquote> <p>Note that OpenGL coordinate space has no notion of integers, everything is a float and the "centre" of an OpenGL pixel is really at the 0.5,0.5 instead of its top-left corner. Therefore, if you want a 1px wide line from 0,0 to 10,10 inclusive, <strong>you really had to draw a line from 0.5,0.5 to 10.5,10.5.</strong></p> <p>This will be especially apparent if you turn on anti-aliasing, if you have anti-aliasing and you try to draw from 50,0 to 50,100 you may see a blurry 2px wide line because the line fell in-between two pixels.</p> </blockquote>
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      1. POHow to render perfect wireframed rectangle in 2D mode with OpenGL?
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      1. POHow to render perfect wireframed rectangle in 2D mode with OpenGL?
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    1. COHow about two nested rectangles?
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    2. CO@stark, how will that fix anything...?
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    3. COMake the white inner one 2*N narrower and shorter than the black outer one, where N is the width of your frame. This works if it is ok to fill the interior. If you really want a frame, then maybe try GL_LINE_LOOP.
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