pixel coordinates for BitmapExpression

[shviller]

Hello guys. Really sorry if this was already discussed (or, hopefully, even implemented), but I'd love two additional variables available inside BitmapExpression.

There are already X and Y that return the current coordinates in the 0..1 range. I'd love to be able to access the actual coordinates of a pixel. That is, for a pixel with X=1.0, Y=1.0 on a 64x128 bitmap, those coordinates will be PX=63, PY=127.

I know that

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int PX = round(X*(16<<BitmapName.Width));
int PY = round(Y*(16<<BitmapName.Height));

but I'm not sure about the whole half pixel offset thing, and I'd very much love to have a shortcut.

The use case is creating lookup textures for complex effects.

Thanks in advance!