Geometry shaders follow a pattern that results in out of bound reads.
This pattern is:
- VSETP to predicate
- Use that predicate to conditionally set a register a big number
- Use the register to access geometry shaders
At the time of writing this commit I don't know what's the intent of
this number. Some drivers argue about these out of bound reads. To avoid
this issue, input reads are guarded limiting reads to the highest
posible vertex input of the current topology (e.g. points to 1 and
triangles to 3).
Rather than have a transparent dependency, we can make it explicit in
the interface. This also gets rid of the need to put the core include in
a header.
The std::string generation with its malloc and free requirement
was a noticeable overhead. Also switch to an ordered_map to
avoid the std::hash call. As those maps usually have a size of
two elements, the lookup time shall not matter.
