Whats holding ~100% D GUI back?

[Gregor Mückl]

On Friday, 29 November 2019 at 08:45:30 UTC, Gregor Mückl wrote:
> On Friday, 29 November 2019 at 06:02:40 UTC, Ola Fosheim 
> Grostad wrote:
>> So you need a CPU software renderer to fall back on, GPU 
>> rendering is more of an optimization in addition to CPU 
>> rendering. But more and more is moving to the GPU.
>>
>> Look at the roadmap for Skia to get an idea.
>
> Yes, proper drawing of common 2d graphics primitives is hard.

Accidentially hit send too early. Sorry.

I am not aware of a full GPU implementation of a TTF or OTF font 
renderer. Glyphs are defined as 2nd or 3rd order splines, but 
these are warped according to pretty complex rules. All of that 
is often done with subpixel precision to get proper antialiasing.

These 2d rendering engine in Qt, cairo, Skia... contain proper 
implememtations for primitives like arcs, polylines with various 
choices for joints and end caps, filled polygons with correct 
self-intersection handling, gradients, fill patterns, ... All of 
these things can be done on GPUs (most of it has), but I highly  
doubt that this would be that much faster. You need lots of 
different shaders for these primitives and switching state while 
rendering is expensive.