This uses a light parser / string modification pass to convert
C++ enum declaration syntax to GLSL compatible one.
GLSL having no support for enums, we are forced to convert the
enum values to a series of constant uints.
The parser (not really one by the way), being stupidly simple,
will not change anything to the values and thus make some C++
syntax (like omitting the values) not work.
The string replacement happens on all GLSL files on startup.
I did not measure significant changes in blender startup speed.
There is plans to do all of this at compile time.
We limit the scope of the search to `.h` and `.hh` files to prevent
confusing syntax in `.glsl` files.
There is basic error reporting with file, line and char logging
for easy debuggabiliy.
The requirements to use this enum sharing system are already listed in
`gpu_shader_shared_utils.h` and repeated on top of the preprocessor
function.
This is a first part of the Shader Create Info system could be.
A shader create info provides a way to define shader structure, resources
and interfaces. This makes for a quick way to provide backend agnostic
binding informations while also making shader variations easy to declare.
- Clear source input (only one file). Cleans up the GPU api since we can create a
shader from one descriptor
- Resources and interfaces are generated by the backend (much simpler than parsing).
- Bindings are explicit from position in the array.
- GPUShaderInterface becomes a trivial translation of enums and string copy.
- No external dependency to third party lib.
- Cleaner code, less fragmentation of resources in several libs.
- Easy to modify / extend at runtime.
- no parser involve, very easy to code.
- Does not hold any data, can be static and kept on disc.
- Could hold precompiled bytecode for static shaders.
This also includes a new global dependency system.
GLSL shaders can include other sources by using #pragma BLENDER_REQUIRE(...).
This patch already migrated several builtin shaders. Other shaders should be migrated
one at a time, and could be done inside master.
There is a new compile directive `WITH_GPU_SHADER_BUILDER` this is an optional
directive for linting shaders to increase turn around time.
What is remaining:
- pyGPU API {T94975}
- Migration of other shaders. This could be a community effort.
Reviewed By: jbakker
Maniphest Tasks: T94975
Differential Revision: https://developer.blender.org/D13360
