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0 pointsjwilm8y ago0 comments

> Skia is definitely capable of good performance, as it resolves down to OpenGL draw calls, pretty much the same as Alacritty, WebRender, and now xi-mac.

This claim is a bit surprising to me. I was under the impression Skia is an immediate mode renderer which ends up issuing a lot GL calls that could be avoided with a retained mode renderer.

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kllrnohj8y ago

An immediate-style API does not mean the work is performed immediately. Skia defers and reorders internally to batch commands so minimal GL state changes are required.

That said a "lot of GL calls" for a 2D UI is actually a trivially insignificant number of GL calls to the actual GPU/driver for most cases. That's basically never the bottleneck unless you've done something insanely wrong.

IshKebab8y ago

I wouldn't be so sure. A single draw call is surprisingly slow. If you drew each glyph with one draw call that could be hundreds which will definitely cause slowness.

kllrnohj8y ago

"hundreds" is actually what I meant by insignificant to a modern driver.

For example: https://images.anandtech.com/graphs/graph11223/86100.png

Granted that's a 1060 but since we're looking at driver CPU overhead that shouldn't matter much. So 2.3 million draw calls per second in DX11 single threaded.

It's not until you start getting into the 10k+ draw calls a frame that you are putting your 60fps at risk.

It's often worth the work to avoid this anyway, after all faster is better if you're an engine/renderer, but it takes a lot for it to be an actual _problem_

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0 pointsjwilm8y ago0 comments

> Skia is definitely capable of good performance, as it resolves down to OpenGL draw calls, pretty much the same as Alacritty, WebRender, and now xi-mac.

This claim is a bit surprising to me. I was under the impression Skia is an immediate mode renderer which ends up issuing a lot GL calls that could be avoided with a retained mode renderer.

0 comments

kllrnohj8y ago

An immediate-style API does not mean the work is performed immediately. Skia defers and reorders internally to batch commands so minimal GL state changes are required.

IshKebab8y ago

I wouldn't be so sure. A single draw call is surprisingly slow. If you drew each glyph with one draw call that could be hundreds which will definitely cause slowness.

kllrnohj8y ago

"hundreds" is actually what I meant by insignificant to a modern driver.

For example: https://images.anandtech.com/graphs/graph11223/86100.png

Granted that's a 1060 but since we're looking at driver CPU overhead that shouldn't matter much. So 2.3 million draw calls per second in DX11 single threaded.

It's not until you start getting into the 10k+ draw calls a frame that you are putting your 60fps at risk.

It's often worth the work to avoid this anyway, after all faster is better if you're an engine/renderer, but it takes a lot for it to be an actual _problem_

1 more reply

j / k navigate · click thread line to collapse