Allows basic usage of templated functions.
There is no support for templated struct.
Benefit:
- More readable than macros in shader sources.
- Compatible with C++ tools.
- More sharing possible with host C++ code.
Requirements/Limitations:
- No default arguments to template parameters.
- Must use explicit instantiation for all variant needed.
- Explicit instantiation needs to **not** use argument deduction.
- Calls to template needs to have all template argument explicit
or all implicit.
- Template overload is not supported (redefining the same template
with different template argument or function argument types).
Currently implemented as Macros inside the build-time pre-pocessor,
but that could change to copy-paste to allow better error reporting.
However, the Macros keep the shader code reduced in the final binary
and allow different file to declare different instantiation.
The implementation is done by declaring overloads for each explicit
instantiation.
If a template has arguments not present in function
arguments, then all arguments **values** are appended to the
function name. The explicit template callsite is then modified to use
`TEMPLATE_GLUE` which will call the correct function. This is
why template argument deduction is not supported in this case.
Rel #137446
Pull Request: https://projects.blender.org/blender/blender/pulls/137441
41ed07d55e