[Const-me]

> consider SDL/Pango/Cairo the counterparts for DWrite/DDraw

I’m not sure Cairo is comparable to Direct2D, the ecosystem is too different.

On Windows, Direct3D 11.0 is guaranteed to be available. Even on computers without any GPU (like most cloud VMs) the OS uses a decently performing software emulation called WARP. For this reason, Direct2D is designed from the ground up to use these shaders as much as possible, and it shows because hardware GPUs deliver way more gigaflops than CPUs. For example, on my computer D2D implements anti-aliasing on top of MSAA hardware.

Cairo is cross-platform, and Linux doesn’t have a universally available GPU API. Some Linux computers have GL 4.5+, some have GLES 3.1+ (both GPU APIs have approximate feature parity with D3D11) some others have none of them. For this reason, Cairo renders vector graphics on CPU. Some computers, with slow CPUs and high resolution displays, don’t have the performance to render complicated 2D scenes in realtime on CPU.

This may change some day once Vulkan support on Linux is ubiquitous, but that day is yet to come.

[mort96]

These days, MESA provides llvmpipe as a fallback software implementation of OpenGL. But your point absolutely stands, the various graphics APIs are much less consistently available on Linux than DirectX is on Windows, and the split between OpenGL and OpenGL ES hurts a lot, with a lot of systems (especially ARM Mali based ones) only providing OpenGL ES drivers.

[Const-me]

> a lot of systems (especially ARM Mali based ones) only providing OpenGL ES drivers

And sometimes minor hardware revision of these Mali GPUs change the internal API between user mode and kernel mode halves of these Linux GLES drivers.

The kernel handled it pretty well as it supported both hardware revisions. But my user mode app failed because the new hardware required a different version of that libmali-midgard*.so DLL.

Unlikely to happen on Windows because the GPU driver installs both kernel/user mode halves of the driver in one transaction. Linux doesn’t have ABI for drivers, all kernel mode drivers are pre-compiled into the kernel.

[anthk]

ARM it's a crapshoot, but on X86 once you get the libraries right everything runs.

That's why free software should be a requeriment at least for drivers.

I remember the -fake Intel- GMA500/3000 fiasco. My old GL 2.1 based n270 netbook it's still supported and with a small ~/.drirc it fixes some quirks as it MESA misdetects it as a GL 1.4 device, but overall it's tons better than the PowerVR chipset with an Intel coat.

The GMA500 users are stuck even without EXA.

[anthk]

Linux had XRender and similar.

[Const-me]

Linux XRender is functionally similar to Windows DirectComposition

Linux does not have anything similar to Direct2D, despite it’s technically possible to make it. Here’s a proof of concept for ARMv7 Debian (Raspberry Pi4), on top of GLES 3.1: https://github.com/Const-me/Vrmac/?tab=readme-ov-file#2d-gra...

[kelnos]

> Linux does not have anything similar to Direct2D

Sure it does: WINE. Not only is it similar, but it's the exact same API & ABI.