Re: Drawing many thin vertical lines is very slow
Re: Drawing many thin vertical lines is very slow
- Subject: Re: Drawing many thin vertical lines is very slow
- From: Jens Alfke <email@hidden>
- Date: Thu, 07 May 2015 22:31:38 -0700
> On May 7, 2015, at 9:43 PM, Michael David Crawford <email@hidden> wrote:
>
> Another way would be for me to render the entire view in an offscreen
> image buffer, which I expect I could do far more efficiently than by
> making many calls into UIRectFill or even CoreGraphics.
Actually, no. Rendering in software is much, much slower than letting the GPU do it. Partly because the CPU isn’t as optimized for it as the GPU, and partly because software has to render into general-purpose RAM, and then afterwards that entire pixmap has to be copied into VRAM where the GPU can access it to composite it to the screen.
As I said, any intuition about drawing performance that’s based on 1990s-or-earlier systems is useless nowadays, because the graphics architecture (hardware and software) is so different.
—Jens
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