'The crazy idea was born to emulate the rendering pipeline itself with an interpreter that runs directly on the GPU as a set of monsterous flexible shaders. 'What if we don't have to rely on specialized shaders?' asks the blog post. Finally, one of Dolphin's major contributors, phire, came up with a crazy alternative. That last problem is why, even though there's a popular branch of Dolphin that implements asynchronous shaders, the developers decided not to pursue it as a universal solution. Worse: this actually permanently screws up some games. Essentially, if a shader is supposed to show up, instead of a stutter while it compiles, the game simply skips rendering it. That left one popular solution: asynchronous shader compilation, which is akin to 'pop in' in modern graphics engines.

More critically, this would only work on a game-by-game basis, a big no-no for emulating a console, rather than specific games. What about sharing shader configurations for games between users? That was possible, but like shader caches, those configurations would have to be tossed out frequently with new Dolphin builds. Predicting shaders was considered, but the developers decided it would be too performance intensive, and due to the way games are programmed, likely wouldn't be effective, anyway. One amusing example is generating all the shaders beforehand, but the blog points out there are more possible graphical effects on the GameCube/Wii than there are grains of sand on Earth, so that seems impractical. So the developers tried to figure out a solution. But you're still going to experience stuttering as you encounter new effects, and upgrading builds, changing drivers, etc. That's why as you play games like Metroid Prime in Dolphin, the stuttering becomes less common. Typically a stutter only lasts a couple of frames, but on really demanding scenes with multiple compiling shaders, stutters of over a second are possible.'ĭolphin can cache shaders, so once a game has compiled a shader, it shouldn't cause stuttering again. Usually the compilation will take place in under a frame and users will be none the wiser, but when it takes longer than a frame, the game will visibly stop until the compilation is complete. 'To deal with this disparity, Dolphin's only option is to delay the CPU thread while the GPU thread and the video driver perform the compilation - essentially pausing the emulated GC/Wii. Dolphin has to translate those effects into shaders, and shaders have to be compiled, which takes time. In the GameCube/Wii GPU's case, configurations aren't stored in memory, and they can be called instantly. They can be preconfigured, since the hardware will never change. Consoles have fixed hardware, unlike PCs, so their shaders aren't written in the same way. Understand so far? Okay, so here's the problem with emulating shaders.

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