Re: [cc65] 3dmaze portability

On Fri, Oct 16, 2009 at 11:38:37PM +0200, Oliver Schmidt wrote:
> I didn't find definitive information on if a tgi driver is supposed to
> clip lines. If yes then the C128 (?) and Apple2 drivers don't work
> correctly. A change for the Apple2 driver would be difficult as it
> currently uses a ROM function that just doesn't support clipping.

As far as I remember, the plan was to put clipping into the wrapper, because
it's target independent and this way, clipping must only coded once. But since
I didn't come up with a pixel exact algorithm immediately, I postponed it and
so it never made it into the library. But this is only true for lines - other
primitives (like circles) must do their own clipping.

The reason why the C64 driver has clipping is that it was derived from Stephen
Judds GRLIB code, which clips when drawing pixels.

> If anybody is interested I can send the modified source. Beside the
> change above I leveraged the new "standard driver" feature and added a
> small Apple2 workaround (necessary because of the missing clock()
> function).

Adding at least some error checking would also be a good idea. I mixed up
graphics drivers (used the old one after a new compile), and the program
terminated without a message after creating the labyrinth.

Regards


        Uz


-- 
Ullrich von Bassewitz                                  uz@musoftware.de
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