Thanks to pixel repacking using cpu data cache, this has a low runtime
cost even for TGL_LINEAR.
Adds support for TGL_NEAREST.
Adds support for TGL_MIRRORED_REPEAT, TGL_CLAMP_TO_EDGE and TGL_REPEAT.
Also, add support for more texture clamping and resampling options.
Mipmaps are not supported, although their sampling modes will be
applied - but to the full-size texture instead of selected mipmap.
Note: Texture sampler is still chosen at texture creation time.
longcurrent_color is assigned per vertex, but it is not saved on each
vertex on creation (unlike their "color" attribute, used when lighting
is enabled).
As a consequence, and because rendering happens asynchronously (rather,
following the draw call queue managed by zdirtyrect.cpp when requested
to flip current buffer), longcurrent_color at clipping time can be
different to the one at vertex declaration time, causing color artifacts.
The effect is most noticeable in EMI set shi, in the grog dispenser +
shipyard manager closeup angle, when Guybrush exits the screen by
crossing its right border: dark triangles become visible on his face.
Instead, always use the color attribute, which is already properly
initialised on vertex creation.
Vincent Pelletier
Stefano Musumeci