Quoting Nathanael D. Noblet:
> When under vesa, I would clip simply to make sure I didn't overwrite
> (draw over) something in the background in the area I was drawing. So
> for example, when doing the animation, I clip an area, Fill it with a
> color, blit some images, and blit the moving images into a new place.
> Then I flip (and flipped using NULL). When I did this, the area that I
> had clipped was the only thing to change. Without a change to the code,
> when I do this I see everything that doesn't get drawn to from the
> previous screen because of the clip, and my new moved images. What is
> the difference between these two behaviours? 

Did you try the "ypan" option for vesafb? You should get the
same behaviour like with the drivers.

> I'm a little confused by what you mean in flipping a subregion always
> copies. Meaning that it copies that region from the back buffer to the
> front, instead of swapping like when you do a flip without a region?

Yes.

> If that is the case, then my program should then follow this:?
> 
> DrawMainMenu (flip using NULL)
> input request NextScreen
> NextScreen()
>       Blank background, draw all static content & FLIP using NULL
>         Iterate animation with clipping & FLIP region.

That's the best way to do that.

Using DSFLIP_BLIT instead of passing a region would have the same
effect, but it would be unnecessarily slower.

> So my question is why didn't this happen before? Especially if it says
> that it is using the BACKSYSTEM instead of BACKVIDEO? I'm just
> confused... Any thoughts on this behaviour?

With BACKSYSTEM the buffers can't be swapped, but with BACKVIDEO.

Without "ypan" you can't use BACKVIDEO with vesafb.

-- 
Best regards,
  Denis Oliver Kropp
 
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