VideoCommon: add a pixel shader asset

[iwubcode]

Here's an asset that describes a pixel shader. I've based my design somewhat off of Unity game engine but I believe other modern graphics renders follow something somewhat similar.

This shader asset contains the shader code for the shader itself, as well as a description of the inputs which match what we want to expose from the shader code. The inputs are just the type (and eventually the default data value), not the actual data that is being held. This makes these assets highly reusable. At the moment, I've only exposed a 2D texture sampler type. But in the future there will be uniform support for colors/integers/etc and likely will also include inputs for cube-maps, 3d textures, and named render targets.

With the data type defined, where does the actual data come from? That is the job of the material asset. That is coming in a subsequent review.

I will be using this in a series of future reviews.

[iwubcode]

I guess I should add. There are many types of shaders. Just from a graphics renderer alone we have:

• Vertex
• Pixel
• Compute
• Geometry
• Tessellation

(if you want to get technical, I believe there are some for Ray Tracing as well but I haven't delved into that)

Dolphin supports the top 4 shader types. I am not sure how many custom variants I want to support.

Unity chose to group the vertex/pixel shader together. Presumably because of how linked they are. Not sure if I want to follow that path.

What is more...we might want to distinguish between the same type based on usage (a custom graphics draw pixel shader is much different than a custom post processing pixel shader!)

I'll be honest, I haven't wrapped my head around all this. This is just a small splash in a complicated topic. I had to start somewhere!

[AdmiralCurtiss]

The code seems fine but I can't say if this is a sensible design or not. If you want me to merge this I will.

[iwubcode]

Thanks for looking it over @AdmiralCurtiss . Anything you're particularly concerned about or any ideas for a better design?

I too don't know if this will stand the test of time. This is (part of) what allows for the shader editing I showed off a few weeks ago so at least it has a neat application.

[AdmiralCurtiss]

Nothing in particular, no. I just am not particularly familiar with loaded asset management stategies.

[iwubcode]

I just am not particularly familiar with loaded asset management stategies.

I am not either. I tried to look up details but didn't find much.

If you feel comfortable merging it, please do as it is pretty critical for the features I'm working on (I have one more related PR coming after this is merged). But if you don't, I understand. I can keep looking for more details.

[Pokechu22]

Unity chose to group the vertex/pixel shader together. Presumably because of how linked they are. Not sure if I want to follow that path.

I feel like that path is a weird choice as it makes it hard to use a geometry shader. Granted, for Dolphin, we generate arbitrary vertex shaders and arbitrary pixel shaders and need to mix them together, but for normal games you probably have a small set of them. But for Dolphin we'd probably want to keep them separate so that each separate component can be added to the generated shaders.