[draft] / [don't merge] Add support for scale_to = original in slang …

[kokoko3k]

…presets for vulkan and glcore drivers

Description

Retroarch supports source,viewport,absolute in shader presets, now it supports "original" too, which is handy for shader writers if they want to return to original dimensions after using anything but "source" in the previous passes.

Reviewers

@hunterk suggested me to open this as a draft, since i was unable to implement the feature for remaining output drivers.

[hizzlekizzle]

@HyperspaceMadness I know you've been interested in this capability for some time.

[HyperspaceMadness]

Looks really good, we just need to get the other drivers covered then we're golden!

@kokoko3k you may want to adjust your commit to keep all the original formatting except in the areas you changed code in,it will make this easier to review

[kokoko3k]

Looks really good, we just need to get the other drivers covered then we're golden!

@kokoko3k you may want to adjust your commit to keep all the original formatting except in the areas you changed code in,it will make this easier to review

I've messed it a bit, btw, the readable commit is this ^_^
2e8bd62

[LibretroAdmin]

OK, so the only error that precludes all tests from passing is this -

gfx/drivers/gl2.c:1818:15: error: enumeration value 'RARCH_SCALE_ORIGINAL' not handled in switch [-Werror,-Wswitch]
switch (fbo_scale->type_x)
^~~~~~~~~~~~~~~~~
gfx/drivers/gl2.c:1842:15: error: enumeration value 'RARCH_SCALE_ORIGINAL' not handled in switch [-Werror,-Wswitch]
switch (fbo_scale->type_y)
^~~~~~~~~~~~~~~~~

If this can be addressed, we can proceed with this PR.

[kokoko3k]

Hope I did right to use width and height instead of gl->tex_w and gl->tex_h

[LibretroAdmin]

Can this PR be merged at this point?

[hizzlekizzle]

@LibretroAdmin it's only for glcore and vulkan currently (i.e., no d3d*). If that's okay, then it's probably fine.

[hizzlekizzle]

lol looks like librashader already merged "original" scale. We gotta keep up! :P