Easy Scalable Text Rendering on the GPU
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Easy Scalable Text Rendering on the GPU
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Re: Easy Scalable Text Rendering on the GPU
#2Minus antialiasing, the stencil buffer version of this technique has been described in the Red Book for a long time: http://www.glprogramming.com/red/chapter14.html#name13
Re: Easy Scalable Text Rendering on the GPU
#3If you want to read on distance field rendering : http://blog.qt.io/blog/2011/07/15/text-rendering-in-the-qml-.... This is used in QML's text rendering (not Qt widgets though).
Re: Easy Scalable Text Rendering on the GPU
#4What I like most about this technique as opposed to other "draw a font as curves in a shader" approaches is that it's actually very fillrate friendly. Instead of drawing a quad and calculating curves (or curve segments) over all of those pixels/fragments, you draw the font outline in polygons which restricts where pixel processing occurs. The whole thing actually reminds me of Carmack's Reverse stencil shadow technique (which grave nice crisp edged shadows but also stopped pixel processing for shadowed regions).
"The code is open source on GitHub in case it’s useful as a reference"
Thank you!
"it’s written in the Skew programming language"
:-(
Thankfully the shader code is in GLSL as you would expect/hope.
Re: Easy Scalable Text Rendering on the GPU
#5What I like most about this technique as opposed to other "draw a font as curves in a shader" approaches is that it's actually very fillrate friendly. Instead of drawing a quad and calculating curves (or curve segments) over all of those pixels/fragments, you draw the font outline in polygons which restricts where pixel processing occurs. The whole thing actually reminds me of Carmack's Reverse stencil shadow techniq…
Well, I'm a bit confused as to how this is fill-rate friendlier than something like [1]: if you are drawing and checking the winding rule via the stencil buffer or color buffer, then you're going to overdraw a lot. A technique like [1], on the other hand, only paints each pixel once.
I would think that, compared to the LUT texture approach, this technique is lighter in FS load but more expensive in terms of fill rate/ROP.
[1]: http://wdobbie.com/post/gpu-text-rendering-with-vector-textu...
Re: Easy Scalable Text Rendering on the GPU
#6> Most anti-aliasing techniques do boundary smoothing by treating each pixel as a little square and visualizing the fraction of the pixel area that is contained inside the outline.
Note that this is a kludge [1].
[1] A Pixel Is Not A Little Square: http://alvyray.com/Memos/CG/Microsoft/6_pixel.pdf
Re: Easy Scalable Text Rendering on the GPU
#7Microsoft Research has in the past developed a similar (though not equivalent) approach: http://research.microsoft.com/en-us/um/people/cloop/LoopBlin...
Re: Easy Scalable Text Rendering on the GPU
#8> Most anti-aliasing techniques do boundary smoothing by treating each pixel as a little square and visualizing the fraction of the pixel area that is contained inside the outline. Note that this is a kludge [1]. [1] A Pixel Is Not A Little Square: http://alvyray.com/Memos/CG/Microsoft/6_pixel.pdf
That essay is written from a particular perspective and pretends that it is the clearly right perspective. Whether it's valid to consider pixels to be little squares depends on whether we're talking about display pixels or image sensor pixels and whether we're trying to resample or interpolate photographic data or trying to create data (pixel art, fonts) for a specific display medium. Sometimes there simply isn't an underlying continuous field to be point-sampled from. You'll never devise a good way to render text on an LCD with that article's mindset (not too surprising, since it's from 1995).
Re: Easy Scalable Text Rendering on the GPU
#9What I like most about this technique as opposed to other "draw a font as curves in a shader" approaches is that it's actually very fillrate friendly. Instead of drawing a quad and calculating curves (or curve segments) over all of those pixels/fragments, you draw the font outline in polygons which restricts where pixel processing occurs. The whole thing actually reminds me of Carmack's Reverse stencil shadow techniq…
> Thankfully the shader code is in GLSL as you would expect
That's not necessarily what I'd expect, given that it's from Microsoft Research. I know they're a pretty independent bunch, but still, kudos.
Re: Easy Scalable Text Rendering on the GPU
#10Very interesting and very clearly explained for someone with no clue about these matters like me. I'd love to read a part two! :)