Comments on: vectors moved by GPU

By: Corey

Corey — Mon, 01 Jun 2009 22:42:07 +0000

That is soo sexy

By: John Stowers

John Stowers — Mon, 01 Jun 2009 21:18:37 +0000

I have heard many rumors of what MDK was working on, and the status that it reached before it was dropped by $employer….

Does anyone wish to share some more information?

By: MacSlow

MacSlow — Mon, 01 Jun 2009 21:08:39 +0000

Gee *sigh* that “reply on comment” in WordPress totally didn’t work. Sorry about that.

By: MacSlow

MacSlow — Mon, 01 Jun 2009 20:18:49 +0000

From my first brief chat with Eric on IRC that GL-backend does map cairo/RENDER’s trapazoids/triangle semantics 1:1 to GL. The approach I’m pursuing takes a path’s control-points and does everything else on the GPU. One could say I’m stepping in a stage earlier. Both methods have advantages and disadvantages. At this point I don’t want to provide a precise breakdown of who does what how efficiently (because I’ve not done that at this stage.. would be a bit stupid to do without more complete implementations to provide real-world test-data). I’m rather glad we trying different things and at the end sees what works best. Maybe it turns out that both have specific app use-cases (e.g. lots of text vs. complex vector-graphics-art). Thanks to cairo’s pluggable rendering-backends we’ll easily be able to use both, without being forced to give one up in favour for the other.

By: MacSlow

MacSlow — Mon, 01 Jun 2009 20:06:19 +0000

From my experience sofar this is overrated. I know about the issues with pixel-correctness brought up at numerous places. But sofar I’ve not seen any noticable issues on my intel and nvidia GPUs. Besides I’m sticking to shaders and the stencil-buffer. The issues often mentioned regarding pixel-correctness relate to different OpenGL-implementations point- and line-drawing. None of those are used here.

By: MacSlow

MacSlow — Mon, 01 Jun 2009 20:00:54 +0000

Basically yes. But to make any real sense the sub-window-less work for gtk+ needs to be in place. Thus … one top-level window == one GL-context … not, like now were it would mean … one gtk+-widget == one GL-context. That could easily kill the machine.

By: mudfly

mudfly — Mon, 01 Jun 2009 19:54:56 +0000

I’ve been watching your work for years, and it is very exciting stuff for the entire community. Keep up the fantastic work!

By: MacSlow

MacSlow — Mon, 01 Jun 2009 19:54:50 +0000

I’m optimistic by the end-result for apps. But the path towards that will be hard.

By: MacSlow

MacSlow — Mon, 01 Jun 2009 19:52:07 +0000

What’s that?

By: MacSlow

MacSlow — Mon, 01 Jun 2009 19:51:46 +0000

Antialiasing in this particular case will be hard! One cannot rely on the GPU’s build-in super and/or multi-sampling (for those that have it). It has to be done in the shader and it isn’t going to be generic solution equally applying for straight and curved parts. The curved parts will need “in-triangle” (the red and blue things in the screencast) anti-aliasing in the shader, while the straight sections will need… actually I’ve no real idea yet for those. What you see in the straight parts (the green things) are not polygon-edges, but stencil-masked cut-outs if you will. Even if one could use hardware super-/multi-sampling, this would be not always equal to cairo’s current anti-aliasing quality (maybe only on very high-end GPUs).